+++ /dev/null
-The swingjs directory contains the current transpiler (net.sf.j2s.core.jar)
-and the run-time core site files (SwingJS-site.zip)
-
-In addition are version directories -- for example, ver/3.1.1 and ver/3.2.1
-
-The second of these, ver/3.2.1, adds Java 8 functionality.
-
-
--- /dev/null
+Notes
+=====
+
+---IMPORTANT CHARACTER SET NOTE---
+
+It is critical that all development work in Java2Script
+be done in UTF-8. This means:
+
+- making sure your Eclipse project is set up for UTF-8 (not the Eclipse default?)
+- making sure your server can serve up UTF-8 by default for any browser-loaded files
+- making sure you don't edit a Java2Script class file or one of the site .js files
+ using a non-UTF-8 editor. It may replace non-Latin characters with "?" or garbage.
+- making sure that your web pages are delivered with proper headings indicating HTML5 and UTF-8
+
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="utf-8">
+
+Note that the DOCTYPE tag is critical for some browsers to switch into HTML5 mode. (MSIE?)
+
+
+
+
+In particular, the Mandarin character 秘 (mi; "secret") is used extensively throughout
+the SwingJS class files to distinguish j2s-specific fields and methods that must not
+ever be shadowed or overridden by subclasses. For example, we see in java.lang.Thread.java:
+
+ public static JSThread 秘thisThread;
+
+----------------------------------
+
+
+updated 12/6/2020 -- note about restrictions on long, including BitSet and Scanner
+updated 3/21/2020 -- adds note about HashMap, Hashtable, and HashSet iterator ordering
+updated 3/20/2020 -- adds note about interning, new String("xxx"), and "xxx"
+updated 2/26/2020 -- adds Graphics.setClip issue
+updated 12/22/19 -- additional issues
+updated 11/03/19 -- adds information about File.exists() and points to src/javajs/async
+updated 10/26/19 -- adds information about File.createTempFile()
+updated 8/16/19 -- minor typos and added summary paragraph
+updated 7/19/19 -- clarification that AWT and Swing classes are supported directly
+updated 5/13/19 -- Mandarin U+79D8 reserved character; Missing Math methods; int and long
+updated 5/10/19 -- adds a section on static issues in multi-(duplicate)-applet pages
+updated 1/4/19 -- nio
+updated 9/15/18 -- adds integer 1/0 == Infinity
+updated 7/24/18 -- most classes replaced with https://github.com/frohoff/jdk8u-jdk
+updated 6/5/17 -- reserved package name "window"
+updated 3/11/17 -- myClass.getField
+updated 3/7/17 -- overloading of JSplitPane.setDividerLocation
+updated 3/2/17 -- more indication of classes not implemented (KeyListener)
+
+=============================================================================
+SwingJS and OpenJDK 8+
+=============================================================================
+
+SwingJS implements a wide range of the Java language in JavaScript. The base
+version for this implementation is OpenJDK8. some classes are implemented using
+older source code, and there are some missing methods. For the most part, this is
+no real problem. You can add or modify any java class just be adding it as source
+in your project. Or (preferably) you can contact me, and I can get it into the
+distribution. Or (even more preferably) you can do that via a patch submission.
+
+=================
+DESIGN PHILOSOPHY
+=================
+
+The java2script/SwingJS design goal is to recreate a recognizable, easily debuggable
+equivalent in JavaScript for as much of Java as practical. This means, for example,
+that one can call in JavaScript
+
+ new java.util.Hashtable()
+
+and for all practical purposes it will appear that Java is running.
+
+
+Method and Field Disambiguation
+-------------------------------
+
+SwingJS has no problem with the overloading of methods, for example:
+
+ public void print(int b);
+ public void print(float b);
+
+JavaScript does not allow overloading of methods, and the common practice in
+Java of naming a field the same as a method -- isAllowed and isAllowed() -- is
+not possible in JavaScript. As a result, SwingJS implements "fully-qualified"
+method names using "$" parameter type separation. Thus, these methods in SwingJS
+will be referred to as print$I and print$F. The rules for this encoding are
+relatively simple:
+
+1. The seven primitive types in Java are encoded $I (int), $L (long), $F (float),
+$D (double), $B (byte) $Z (boolean), and $H (short).
+
+2. String and Object are encoded as $S and $O, respectively.
+
+3. "java_lang_" is dropped for all other classes in the java.lang package (as in Java).
+ For example: $StringBuffer, not $java_lang_StringBuffer
+
+4. All other classes are encoded as
+
+ "$" + Class.getName().replace(".","_")
+
+For example, in Java we see:
+
+ public void equals(Object o) {...}
+
+Whereas in SwingJS we have:
+
+ Clazz.newMeth(C$, 'equals$O', function (o) {...}
+
+And
+
+ this.getContentPane().add(bar, "North");
+
+becomes
+
+ this.getContentPane$().add$java_awt_Component$O(bar, "North");
+
+5. Arrays are indicated with appended "A" for each level. So
+
+ setDataVector(Object[][] dataVector, Object[] columnIdentifiers)
+
+becomes
+
+ setDataVector$OAA$OA(dataVector, columnIdentifiers)
+
+(It is recognized that this design does introduce a bit of ambiguity, in that
+ in principal there could be user class named XA and X in the same package,
+ and methods a(X[]) and a(XA) in the same class that cannot be distinguished.
+ The benefit of this simple system, however, triumphed over the unlikelyhood
+ of that scenario.) The transpiler could be set to flag this possibility.
+
+6. Constructors are prepended with "c$". So
+
+ public JLabel(String text) {...}
+
+becomes:
+
+ Clazz.newMeth(C$, 'c$$S', function (text) {...});
+
+Field disambiguation involves prepending. In Java, a class and its subclass
+can both have the same field name, such as
+
+ boolean visible;
+
+When this happens, it is called "shadowing", and though not recommended, Java allows
+it. The Java2Script transpiler will prepend such shadowing fields with "$" so that the
+subclass instance has both "visible" (for use in its methods inherited from its
+superclass) and "$visible" (for its own methods). Thus, we might see in Java:
+
+ this.visible = super.visible;
+
+while in SwingJS we will see:
+
+ this.$visible=this.visible;
+
+since JavaScript does not have the "super" keyword.
+
+
+
+Parameterless methods such as toString() are appended with "$" to become toString$().
+The one exception to this rule is private methods, which are saved in (truly) private
+array in the class (and are not accessible by reflection). Private parameterless
+methods retain their simple Java name, since they cannot conflict with field names.
+
+This renaming of methods has a few consequences, which are discussed more fully below.
+See particularly the section on "qualified field and method names", where it is described
+how you can use packages or classes or interfaces with ".api.js" in them to represent JavaScript
+objects for which all method names are to be left unqualified. Note that it is not
+possible to cherry-pick methods to be unqualified; only full packages, classes or
+interfaces can hold this status.
+
+The swingjs.api.js package in particular contains a number of useful interfaces that
+you can import into your project for JavaScript-specific capabilities.
+
+
+Applet vs. Application
+----------------------
+
+One of the very cool aspects of SwingJS is that it doesn't particularly matter if a browser-based
+Java app is an "applet" or an "application". We don't need JNLP (Java Network Launch Protocol)
+because now we can just start up any Java application in a browser just as easily as any applet.
+The associative array that passes information to the SwingJS applet (information that formerly
+might have been part of the APPLET tag, such as width, height, and codebase, always referred to
+in our writing as "the Info array") allows the option to specify the JApplet/Applet "code"
+class or the application "main" class. Either one will run just fine.
+
+
+Performance
+-----------
+
+Obviously, there are limitations. One is performance, but we have seen reproducible
+performance at 1/6 - 1/3 the speed of Java. Achieving this performance may require
+some refactoring of the Java to make it more efficient in both Java and JavaScript.
+"for" loops need to be more carefully crafted; use of "new" and "instanceof" need to be
+minimized in critical areas. Note that method overloading -- that is, the same method name
+with different parameters, such as read(int) and read(byte) -- is no longer any problem.
+
+
+Threads
+-------
+
+Although there is only a single thread in JavaScript, meaning Thread.wait(), Thread.sleep(int) and
+Thread.notify() cannot be reproduced, we have found that this is not a serious limitation.
+For example, javax.swing.Timer() works perfectly in JavaScript. All it means is that threads
+that use sleep(int) or notify() must be refactored to allow Timer-like callbacks. That is,
+they must allow full exit and re-entry of Thread.run(), not the typical while/sleep motif.
+
+The key is to create a state-based run() that can be exited and re-entered in JavaScript.
+
+
+Static fields
+-------------
+
+Final static primitive "constant" fields (String, boolean, int, etc.) such as
+
+static final int TEST = 3;
+static final String MY_STRING = "my " + "string";
+
+are converted to their primitive form automatically by the Eclipse Java compiler
+and do not appear in the JavaScript by their names.
+
+Other static fields are properties of their class and can be used as expected.
+
+Note, however, that SwingJS runs all "Java" code on a page in a common "jvm"
+(like older versions of Java). So, like the older Java schema, the JavaScript
+equivalents of both applets and applications will share all of their static
+fields and methods. This includes java.lang.System.
+
+Basically, SwingJS implementations of Java run in a browser page-based sandbox
+instead of an applet-specific one.
+
+In general, this is no problem. But if we are to implement pages with
+multiple applets present, we must be sure to only have static references
+that are "final" or specifically meant to be shared in a JavaScript
+environment only (since they will not be shared in Java).
+
+A simple solution, if static non-constant references are needed, is to attach the
+field to Thread.currentThread.threadGroup(), which is an applet-specific reference.
+Be sure, if you do this, that you use explicit setters and getters:
+
+For example,
+
+private static String myvar;
+
+...
+
+public void setMyVar(String x) {
+ ThreadGroup g = Thread.currentThread().threadGroup();
+ /**
+ * @j2sNative g._myvar = x;
+ *
+ */
+ {
+ myvar = x;
+ }
+}
+
+public String getMyVar() {
+ ThreadGroup g = Thread.currentThread().threadGroup();
+ /**
+ * @j2sNative return g._myvar || null;
+ *
+ */
+ {
+ return myvar;
+ }
+}
+
+ in Java will get and set x the same in JavaScript and in Java.
+
+
+A convenient way to do this in general is to supply a singleton class with
+explicitly private-only constructors and then refer to it in Java and in JavaScript
+instead of using static field, referring to myclass.getIntance().xxx instead of
+myclass.xxx in Java (and JavaScript).
+
+This was done extensively in the Jalview project. See jalview.bin.Instance.
+
+
+Helper Packages -- swingjs/ and javajs/
+---------------------------------------
+
+The SwingJS library is the swingjs/ package. There are interfaces that may be of assistance
+in swingjs/api, but other than that, it is not recommended that developers access classes in
+this package. The "public" nature of their methods is really an internal necessity.
+
+In addition to swingjs/, though, there are several useful classes in the javajs/ package
+that could be very useful. This package is a stand-alone package that can be
+cloned in any Java project that also would be great to have in any JavaScript project
+-- SwingJS-related or not. Functionality ranges from reading and writing various file
+formats, including PDF, BMP, PNG, GIF, JPG, JSON, ZIP, and CompoundDocument formats.
+
+A variety of highly efficient three- and four-dimensional point, vector, matrix, and
+quaternion classes are included, as they were developed for JSmol and inherited from that
+project.
+
+Of particular interest should be javajs/async/, which includes
+
+javajs.async.Async
+javajs.async.AsyncColorChooser
+javajs.async.AsyncDialog
+javajs.async.AsyncFileChooser
+
+See javajs.async.Async JavaDoc comments for a full description of
+these useful classes.
+
+
+Modal Dialogs
+-------------
+
+Although true modal dialogs are not possible with only one thread, a functional equivalent --
+asynchronous modal dialogs -- is relatively easy to set up. All the JOptionPane dialogs will
+return PropertyChangeEvents to signal that they have been disposed of and containing the results.
+See below and classes in the javajs.async package.
+
+
+Native calls
+------------
+
+Native calls in Java are calls to operating system methods that are not in Java. JavaScript
+has no access to these, of course, and they must all be replaced by JavaScript equivalents.
+Fortunately, they are not common, and those that are present in Java (for example, in calculating
+checksums in ZIP file creation) are at a low enough level that most developers do not utilize them
+or do not even have access to them. All native calls in Java classes have been replaced by
+Java equivalents.
+
+
+Swing GUI Peers and UIClasses
+-----------------------------
+
+One of the biggest adaptations introduced in SwingJS is in the area of the graphical
+user interface. The issue here is complex but workable. In Java there are two background
+concepts -- the Component "peer" (one per "heavy-weight" component, such as a Frame) and the
+component "uiClass" (one per component, such as JButton or JTextField).
+
+Peers are native objects of the operating system. These are the virtual buttons and text areas
+that the user is interacting with at a very base level. Their events are being passed on to
+Java or the browser by the operating system. UI classes provide a consistent "look and feel"
+for these native objects, rendering them onto the native window canvas and handling all
+user-generated events. They paint the borders, the backgrounds, the highlights, of every
+control you see in Java. There is one-to-one correspondence of Swing classes and UI classes.
+Setting the Look and Feel for a project amounts to selecting the directory from which to draw
+these UI classes. The UI classes can be found in the javax.swing.plaf ("platform look and feel")
+package.
+
+Early on in the development of SwingJS, we decided not to fully reproduce the painfully detailed
+bit-by-bit painting of controls as is done in Java. Instead, we felt it was wiser to utilize the standard
+HTML5 UI capabilities as much as possible, using DIV, and INPUT especially, with extensive use
+of CSS and sometimes jQuery (menus, and sliders, for example). Thus, we have created a new
+set of UIs -- the "HTML5 Look and Feel". These classes can be found in swingjs.plaf. Besides being
+more adaptable, this approach allows far more versatility to SwingJS developers, allowing them
+to modify the GUI to suit their needs if desired.
+
+In SwingJS, since we have no access to native peers except through the browser DOM,
+it seemed logical to merge the peer and UI idea. So instead of having one peer per heavy-weight control and
+one UI class instance for each control type, we just have one UI class instance per control, and
+that UI class instance is what is being referred to when a "peer" is notified.
+
+In some ways this is a throw back to when all of Swing's components were subclasses of
+specific AWT components such as Button and List. These "heavy-weight components" all had their
+own individual native peers and thus automatically took on the look and feel provided by the OS.
+Later Swing versions implemented full look and feel for all peers, leaving only JDialog, JFrame,
+and a few other classes to have native peers. But in SwingJS we have again a 1:1 map of component
+and UI class/peer instance.
+
+The origin of most issues (read "bugs") in relation to the GUI will probably be found in the
+swingjs.plaf JSxxxxUI.java code.
+
+
+Swing-only Components -- no longer an issue
+-------------------------------------------
+
+Swing was introduced into Java well after the Java Abstract Window Toolkit (AWT) was well
+established. As such, its designers chose to allow AWT controls such as Button and List to be used
+alongside their Swing counterparts JButton and JList. Reading the code, it is clear that this
+design choice posed a huge headache for Swing class developers.
+
+For SwingJS, we decided from the beginning NOT to allow this mixed-mode programming and
+instead to require that all components be Swing components.
+
+However, this is no longer an issue. All AWT components in SwingJS are now subclasses of
+javax.swing.JComponent. So far, we have found no problem with this.
+
+
+The a2s Adapter Package
+-----------------------
+
+Originally, we thought that we would restrict ourselves to JApplets only. That is, only
+Swing-based applets. But as we worked, we discovered that there are a lot of great
+applets out there that are pre-Swing pure-AWT java.applet.Applet applets. Our problem was
+that we also wanted it to be possible to quickly adapt these applets to JavaScript as well.
+
+The solution turned out to be simple: Write a package (a2s) that recreates the interface for
+non-Swing components as subclasses of Swing components. Thus, a2s.Button subclasses javax.swing.JButton
+but also accepts all of the methods of java.awt.Button. This works amazingly well, with a few
+special adaptations to the core javax.swing to be "AWT-aware." All AWT components now subclass
+a2s components, which in turn subclass JComponents. So no changes in code are necessary. We have
+successfully transpiled over 500 applets using this strategy. (Kind of surprising, actually, that
+the original Java developers did not see that option. But we have a hindsight advantage here.)
+
+
+Working with Files
+==================
+
+Simple String file names are not optimal for passing information about
+read files within SwingJS applications.
+
+All work with files should either use Path or File objects exclusively.
+These objects, after a file is read or checked for existence, will already
+contain the file byte[] data. Doing something like this:
+
+File f = File("./test.dat");
+boolean isOK = f.exists();
+
+will load f with its byte[] data, if the file exists.
+
+But if after that, we use:
+
+File f2 = new File(f.getAbsolutePath());
+
+f2 will not contain that data. Such copying should be done as:
+
+File f2 = new File(f);
+
+in which case, the byte[] data will be transferred.
+
+
+SwingJS uses the following criteria to determine if File.exists() returns true:
+
+(1) if this File object has been used directly to read data, or
+(2) if reading data using this File object is successful.
+
+Note that you cannot check to see if a file exists before input or if it
+was actually written or if it already exists prior to writing in SwingJS.
+
+Thus, you should check each use of file.exists() carefully, and if necessary, provide a J2sNative
+block that gives an appropriate "OK" message, for example:
+
+(/** @j2sNative 1 ? false : */ outputfile.exits())
+
+or
+
+(/** @j2sNative 1 ? true : */ inputfile.exits())
+
+Temporary files can be created in SwingJS. SwingJS will maintain a pseudo-filesystem for files
+created with File.createTempFile(). This is useful in that closure of writing to a temporary file
+does not generate a pseudo-download to the user's machine.
+
+
+UNIMPLEMENTED CLASSES BY DESIGN
+===============================
+
+The SwingJS implementation of the following classes are present
+in a way that gracefully bypasses their functionality:
+
+accessibility
+security
+serialization
+
+
+
+TODO LIST FOR UNIMPLEMENTED CLASSES
+===================================
+
+JEditorPane (minimal implementation) - DONE 12/2018; some issues still
+JSplitPane - DONE 8/2018
+JTabbedPane - DONE 10/2018
+JTree - done 12/2019
+
+
+MINOR ISSUES--required some rewriting/refactoring by Bob and Udo
+================================================================
+
+Thread.currentThread() == dispatchThread
+
+
+MINOR ISSUES--requiring some rewriting/refactoring outside of SwingJS
+=====================================================================
+
+See below for a full discussion.
+
+Restrictions on long
+Restriction on BitSet and Scanner
+HashMap, Hashtable, and HashSet iterator ordering
+interning, new String("xxx") vs "xxx"
+Names with "$" and "_"
+positive integers do not add to give negative numbers
+ArrayIndexOutOfBounds
+java.awt.Color
+native methods
+javax.swing.JFileDialog
+key focus
+LookAndFeel and UI Classes
+System.exit(0) does not stop all processes
+list cell renderers must be JComponents
+myClass.getField not implemented
+"window" and other reserved JavaScript names
+reserved field and method names
+qualified field and method names
+missing Math methods
+Component.getGraphics(), Graphics.dispose()
+Graphics.setClip()
+
+MAJOR ISSUES--for Bob and Udo within SwingJS
+============================================
+
+fonts
+OS-dependent classes
+AWT component peers
+some aspects of reflection
+
+MAJOR ISSUES--to be resolved by implementers
+============================================
+
+fonts
+threads
+modal dialogs
+image loading
+BigDecimal not fully implemented
+no format internationalization
+no winding rules
+text-related field implementation
+Formatter/Regex limitations
+integer 1/0 == Infinity
+
+========================================================================
+
+DISCUSS
+=======
+
+Table row/col sorter needs checking after removal of java.text.Collator references
+
+I had to move all of SunHints class to RenderingHints, or the
+two classes could not be loaded. Shouldn't be a problem, I think. The sun classes are
+not accessible to developers in Java anyway, since they are generally package private.
+
+==========================================================================
+
+//////////////////////////////////////////////////////////////////////////////
+
+UNIMPLEMENTED CLASSES
+=====================
+
+accessibility
+-------------
+
+All Accessibility handling has been commented out to save the download footprint.
+This removes the need for sun.misc.SharedSecrets as well.
+Nothing says we could not implement accessibility. We just didn't.
+
+
+security
+--------
+
+All JavaScript security is handled by the browser natively.
+Thus, Java security checking is no longer necessary, and
+java.security.AccessController has been simplified to work without
+native security checking.
+
+Note that private methods in a class are REALLY private.
+
+
+serialization
+-------------
+
+All serialization has been removed. It was never very useful for Swing anyway,
+because one needs exactly the same Java version to save and restore serialized objects.
+
+
+keyboard accelerators and mnemonics
+-----------------------------------
+
+This work was completed in the spring of 2019. Note that in a browser, some
+key strokes, particularly CTRL-keys, are not available. Bummer.
+
+
+MINOR ISSUES--required some rewriting/refactoring by Bob and Udo
+================================================================
+
+
+Thread.currentThread() == dispatchThread
+----------------------------------------
+
+changed to JSToolkit.isDispatchThread()
+
+
+MINOR ISSUES--requiring some rewriting/refactoring outside of SwingJS
+=====================================================================
+
+restrictions on long
+--------------------
+
+Java's 64-bit long type is not supported in JavaScript. There is no Int64Array in JavaScript,
+and 0x20000000000000 + 1 evaluates to 0x20000000000000, not 0x20000000000001.
+(Likewise, -0x20000000000000 - 1 is left unchanged.)
+
+The largest "integer" value in JavaScript is 9007199254740991 (9.007199254740991E13, or 0x1FFFFFFFFFFFFFF).
+Effectively, you get to use only 53 bits of the long, not 64. Trying to set a long larger than
+0x1FFFFFFFFFFFFFF or smaller than -0x1FFFFFFFFFFFFFF will result in a NumberFormatException.
+
+The transpiler handles conversion to long the same as Java for all cases other than from double.
+
+For small double values, there is no problem, and, in fact, this is a known trick used to round
+doubles and floats toward zero:
+
+double d;
+d = (long) 3.8;
+assert(d == 3);
+d = (long) -3.8;
+assert(d == -3);
+
+SwingJS will evaluate (long) d as 0 for d > 9007199254740991
+or d < -9007199254740991, same as Java returns for Double.NaN.
+So, in Java we have:
+
+ assert(((long) Double.NaN) == 0);
+ assert(((int) Double.NaN) == 0);
+ assert(((long) Float.NaN) == 0);
+ assert(((int) Float.NaN) == 0);
+
+and also, in JavaScript only, we also have:
+
+ double d = 0x2000000000000L;
+ assert(((long) d) == 0);
+
+
+restrictions on BitSet and Scanner
+----------------------------------
+
+Because of the issue of long being only 53 bits, any time a method returns a long value, considerations must
+be made as to whether this will work in JavaScript. In particular, BitSet and Scanner have issues.
+
+In SwingJS, java.util.BitSet has been implemented as a 32-bit integer-based bitset. This was no problem in
+Java 6, but starting with Java 7, a method was added to BitSet that allows for the extraction of the
+underlying long[] word data. This is not work in JavaScript. Instead, SwingJS java.util.Bitset.toLongArray() will deliver
+32-bit int[] data.
+
+SwingJS Scanner has hasNextLong() and nextLong(), and although it will scan through long numbers,
+Scanner will choke on long numbers greater than the JavaScript 53-bit limit. hasNextLong() will
+return false, and nextLong() will throw an InputMismatchException triggered by the NumberFormatException
+thrown by Long.parseLong().
+
+
+HashMap, Hashtable, and HashSet iterator ordering
+-------------------------------------------------
+
+In Java, iterators for HashMap, Hashtable, and HashSet do not guarantee any particular order.
+From the HashMap documentation for Java 8:
+
+ This class makes no guarantees as to the order of the map; in particular, it does not
+ guarantee that the order will remain constant over time.
+
+Likewise, for HashSet (because it is simply a convenience method for HashMap<Object,PRESENT>:
+
+ [HashSet] makes no guarantees as to the iteration order of the set.
+
+JavaScript's Map object is different. It is basically a LinkedHashMap, so it guarantees iteration
+in order of object addition.
+
+Starting with java2script 3.2.9.v1, these classes use the JavaScript Map object rather than hash codes
+whenever all keys are strictly of JavaScript typeof "string". If any key is introduced that is not a string, the
+implementation falls back to using hash codes, the same as Java.
+
+Note strings created using new String("xxxx") are NOT typeof "string"; they are typeof "object".
+
+The result is significantly faster performance (3-12 x faster) than originally, and up to 3 x faster
+performance in JavaScript than in Java itself. Right. Faster than Java.
+
+The JavaScript Map implementation is implemented UNLESS the constructor used is the one that
+specifies both initial capacity and load factor in their constructor. Thus,
+
+new Hashtable()
+new HashMap()
+new HashMap(16)
+new HashSet()
+
+all use the JavaScript Map. But
+
+new Hashtable(11, 0.75f)
+new HashMap(16, 0.75f)
+new HashSet(16, 0.75f)
+
+do not.
+
+This design allows for opting out of the JavaScript Map use in order to retain the exact behavior of
+iterators in JavaScript as in Java.
+
+
+interning, new String("xxx") vs "xxx"
+-------------------------------------
+
+Note that the following are true in JavaScript:
+
+typeof new String("xxxx") == "object"
+typeof "xxxx" == "string"
+var s = "x";typeof ("xxx" + s) == "string"
+
+There is no equivalence to this behavior in Java, where a String is a String is a String.
+
+Be aware that SwingJS does not always create a JavaScript String object using JavaScript's
+new String(...) constructor. It only does this for Java new String("xxxx") or new String(new String()).
+
+In all other cases, new String(...) (in Java) results in a simple "xxxx" string in JavaScript.
+That is, it will be JavaScript typeof "string", not typeof "object".
+
+The reason for this design is that several classes in the Java core use toString()
+methods that return new String(), and those classes that do that would cause a JavaScript error
+if implicitly stringified if new String() returned a JavaScript String object.
+
+This is fine in JavaScript
+
+test1 = function() { return { toString:function(){ return "OK" } } }
+"testing" + new test1()
+>> "testingOK"
+
+But for whatever reason in JavaScript:
+
+test2 = function() { return { toString:function(){ return new String("OK") } } }
+"testing" + new test2()
+>> Uncaught TypeError: Cannot convert object to primitive value
+
+The lesson here is never to use
+
+ return new String("...");
+
+in a Java toString() method. In Java it will be fine; in JavaScript it will also be fine as long as
+that method is never called in JavaScript implicitly in the context of string concatenation.
+
+A note about interning. Consider the following six Java constructions, where we have a == "x";
+
+"xxx"
+"xx" + "x"
+new String("xxx").intern()
+
+new String("xxx")
+"xx" + a.toString()
+"xx" + a
+
+All six of these will return java.lang.String for .getClass().getName().
+However, the first three are String literals, while the last three are String objects.
+Thus:
+ "xxx" == "xxx"
+ "xxx" == "xx" + "x"
+ "xxx" == new String("xxx").intern()
+
+but none of the other three are equivalent to "xxx" or each other:
+
+ "xxx" != new String("xxx")
+ "xxx" != "xx" + a.toString()
+ "xxx" != "xx" + a
+ new String("xxx") != new String("xxx")
+ "xx" + a != new String("xxx")
+
+etc.
+
+As in Java, in SwingJS, all of the following Java assertions pass as true:
+
+ assert("xxx" == "xx" + "x");
+ assert("xxx" == ("xx" + a).intern());
+ assert("xxx" === new String("xxx").intern());
+
+and both of these do as well:
+
+ assert(new String("xxx") != "xxx");
+ assert(new String("xxx") != new String("xxx"));
+
+But the following two fail to assert true:
+
+ assert("xxx" != "xx" + a);
+ assert("xxx" != "xx" + a.toString());
+
+because in JavaScript, both of these right-side expressions evaluate to a simple "interned" string.
+
+In Java, however, these assertions are true because Java implicitly "boxes" String
+concatentaion as a String object, not a literal.
+
+Most of us know not to generally use == with Strings unless they are explicitly interned.
+Where this problem may arise, though, is in IdentityHashMap, which compares objects using
+System.identityHashCode(), which is not the same for different objects or their string literal equivalents.
+
+My recommendation, if you need to use IdentityHashMap with strings is to always use an explicit String.intern()
+for any keys -- unless you really want to keep every string as separate keys even if they are the same sequence,
+in which case, use new String(). This will work in Java and in JavaScript.
+
+Be aware when working with strings that come from SwingJS and are being used by other JavaScript modules
+that those that are String objects will return "object" for the JavaScript typeof operator, not "string".
+
+The easy way to ensure this is no problem is to concatenate strings with "" to force immediate interning:
+
+ var x = aJavaObject.getString() + "";
+
+unless you are certain that the string is being returned is a raw JavaScript string.
+
+Names with "$" and "_"
+----------------------
+
+For the most part, this should be no problem.
+
+Note that the use of $ and _ in Java field names has always been discouraged:
+[https://docs.oracle.com/javase/tutorial/java/nutsandbolts/variables.html]
+
+ You may find some situations where auto-generated names will contain the dollar sign,
+ but your variable names should always avoid using it. A similar convention
+ exists for the underscore character; while it's technically legal to begin your
+ variable's name with "_", this practice is discouraged.
+
+Some impacts of transpiling method names with full qualification:
+
+1) SwingJS will introduce fields that start with $ or _. These will not conflict
+ if the above convention is followed.
+
+2) Fields that have the same Java name as a method are not an issue.
+
+3) Fields that have a Java name with $ that matches a transpiled method name,
+ such as toString$, will need to be refactored in Java to not have that name collision.
+
+4) Fields in a subclass that have the same name as private fields in a superclass
+ represent a name collision, because the superclass method needs to call its private
+ field even if invoked from a subclass. The solution was to modify the subclass field
+ name using one or more prepended $.
+
+5) Use of Class.getDeclaredMethods() reflection will return Method objects having the transpiled
+ name, not the Java name. This could require some j2sNative adjustment
+ to strip the $... parameters from the name if that is needed.
+
+6) Use of Method.getParameterTypes() should work fine, provided class names
+ do not contain "_". This is because the transpiler converts "." to "_" when
+ creating the fully qualified JavaScript name.
+
+
+positive integers do not add to give negative numbers
+-----------------------------------------------------
+
+In Java, the following is true:
+
+ 2000000000 + 2000000000 == -294967296
+
+But in SwingJS, that will be 4000000000. So, for example, the following
+strategy will fail in SwingJS:
+
+ int newLength = lineBuf.length * 2;
+ if (newLength < 0) {
+ newLength = Integer.MAX_VALUE;
+ }
+
+"-1" in JavaScript is not 0xFFFFFFFF.
+
+And one must take care to not compare a negative number with a 32-bit mask. So
+
+(b & 0xFF000000) == 0xFF000000
+
+is true in Java for (int) b = -1, but is false in JavaScript, because 0xFF000000 is 4278190080,
+while (-1 & 0xFF000000) is, strangely enough, -16777216, and, in fact,
+
+(0xFF000000 & 0xFF000000) != 0xFF000000
+
+because -16777216 is not 4278190080.
+
+The fix is that one must compare similar operations:
+
+if ((b & 0xFF000000) == (0xFF000000 & 0xFF000000)) .....
+
+Importantly, the JavaScript Int32Array does behave properly. From
+the Firefox developer console:
+
+>> x = new Int32Array(1)
+<- Int32Array(1) [ 0 ]
+>> x[0] = 4000000000
+<- 4000000000
+>> x[0]
+<- -294967296
+
+Notice that, perhaps unexpectedly, the following two constructs produce
+different results in JavaScript:
+
+x = new Int32Array(1);
+b = x[0] = 4000000000;
+
+(b will be 4000000000)
+
+and
+
+x = new Int32Array(1);
+x[0] = 4000000000;
+b = x[0];
+
+(b will be -294967296)
+
+
+SwingJS leverages array typing to handle all byte and short arithmetic so as
+to ensure that any byte or short operation in JavaScript does give the same
+result in Java. The design decision to not also do this with integer math was
+a trade-off between performance and handling edge cases.
+
+
+ArrayIndexOutOfBounds
+---------------------
+
+You cannot implicitly throw an ArrayIndexOutOfBoundsException in JavaScript.
+JavaScript will simply return "undefined", not throw an Exception. So:
+
+boolean notAGoodIdeaIsOutOfBounds(String[] sa, int i) {
+ try {
+ return (sa[i] == sa[i]);
+ } catch (ArrayIndexOutOfBoundsException e) {
+ return false;
+ }
+}
+
+will work in Java but not in JavaScript. Code should not depend upon this sort
+of trap anyway, if you ask me.
+
+Throwable vs Error vs Exception
+-------------------------------
+
+True JavaScript errors are trapped as Throwable, whereas you can still trap
+Error and Exception as well. So if you want to be sure to catch any JavaScript
+error, use try{}catch (Throwable t){}, not try{}catch (Exception e){}.
+
+j
+ava.awt.Color
+--------------
+
+ColorSpace: only "support" CS_sRGB.
+
+ TODO -- any volunteers??
+
+
+javax.swing.JFileDialog
+-----------------------
+
+HTML5 cannot expose a file reading directory structure. But you certainly
+can still do file reading and writing. It just works a little differently.
+It's a simple modification:
+
+ b = new JButton("FileOpenDialog");
+ b.addActionListener(new ActionListener() {
+
+ @Override
+ public void actionPerformed(ActionEvent e) {
+ JFileChooser fc = new JFileChooser();
+ Test_Dialog.this.onDialogReturn(fc.showOpenDialog(Test_Dialog.this));
+ // Java will wait until the dialog is closed, then enter the onDialogReturn method.
+ // JavaScript will exit with NaN immediately, and then call back with its actual value
+ // asynchronously.
+ }
+
+ });
+
+ public void onDialogReturn(int value) {
+ if (value != Math.floor(value))
+ return; // in JavaScript, this will be NaN, indicating the dialog has been opened
+ // If we are here, the dialog has closed, in both Java and JavaScript.
+ System.out.println("int value is " + value);
+ }
+
+
+ @Override
+ public void propertyChange(PropertyChangeEvent event) {
+ Object val = event.getNewValue();
+ String name = event.getPropertyName();
+ System.out.println(name);
+ switch (event.getSource().getClass().getName()) {
+ case "javax.swing.JOptionPane":
+ switch (name) {
+ case "inputValue":
+ onDialogReturn(val);
+ return;
+ case "value":
+ if (val instanceof Integer)
+ onDialogReturn(((Integer) val).intValue());
+ else
+ onDialogReturn(val);
+ return;
+ }
+ break;
+ case "javax.swing.ColorChooserDialog":
+ switch (name) {
+ case "SelectedColor":
+ onDialogReturn(val);
+ return;
+ }
+ break;
+ case "javax.swing.JFileChooser":
+ switch (name) {
+ case "SelectedFile":
+ File file = (File) val;
+ byte[] array = (val == null ? null : /** @j2sNative file.秘bytes || */
+ null);
+ onDialogReturn("fileName is '" + file.getName() + "'\n\n" + new String(array));
+ return;
+ }
+ break;
+ }
+ System.out.println(
+ event.getSource().getClass().getName() + " " + event.getPropertyName() + ": " + event.getNewValue());
+ }
+
+
+Developers are encouraged to create a separate class that handles general calls to JFileDialog.
+An example class can be found in the SwingJS distribution as
+
+/sources/net.sf.j2s.java.core/src/javajs/async/AsyncFileChooser.java.
+
+
+javax.swing.JOptionPane dialogs
+-------------------------------
+
+For this action to work, the parentComponent must implement
+propertyChangeListener, and any call to JOptionPanel should allow for
+an asynchronous response, meaning that there is no actionable code following the
+call to the dialog opening.
+
+In addition, for compatibility with the Java version, implementation should
+wrap the call to getConfirmDialog or getOptionDialog in a method call to
+handle the Java:
+
+onDialogReturn(JOptionPane.showConfirmDialog(parentFrame,
+messageOrMessagePanel, "title", JOptionPane.OK_CANCEL_OPTION));
+
+Then parentFrame.propertyChange(event) should also call onDialogReturn.
+
+This will then work in both Java and JavaScript.
+
+Note that there is an int and an Object version of onDialogReturn().
+
+
+In JavaScript:
+
+The initial return from JOptionPane.showConfirmDialog and showMessageDialog
+will be (SwingJS) JDialog.ASYNCHRONOUS_INTEGER (NaN), testable as an impossible
+Java int value using ret != -(-ret) if the parent implements PropertyChangeListener, or -1
+(CLOSE_OPTION) if not.
+
+For showOptionDialog (which returns Object) or showInputDialog (which returns
+String), the initial return will be (SwingJS) JDialog.ASYNCHRONOUS_OBJECT, testable as
+((Object) ret) instanceof javax.swing.plaf.UIResource if the parent implements
+PropertyChangeListeneer, or null if not.
+
+The second return will be the desired return.
+
+In Java:
+
+The initial return will be the one and only modal final return.
+
+
+
+For full compatibility, The calling method must not continue beyond this
+call.
+
+All of the standard Java events associated with Components are also
+available.
+
+Certain fall back mechanisms are possible, where onReturn does not exist, but
+only for the following cases:
+
+
+For showMessageDialog, for WARNING_MESSAGE and ERROR_MESSAGE, a simple
+JavaScript alert() is used, returning 0 (OK_OPTION) or -1 (CLOSED_OPTION).
+
+For showInputDialog, if the message is a string, a simple JavaScript prompt()
+with input box is used, returning the entered string or null.
+
+For showConfirmDialog, a simple JavaScript confirm() is used, in which case:
+
+for YES_NO_OPTION: YES_OPTION or NO_OPTION
+
+for YES_NO_CANCEL_OPTION: YES_OPTION or CANCEL_OPTION
+
+for OK_CANCEL_OPTION or any other: OK_OPTION or CANCEL_OPTION
+
+Note that you should implement a response for CLOSED_OPTION for
+showConfirmDialog. For other dialogs, a null return indicates the dialog was
+closed, just as for Java.
+
+Developers are encouraged to create a separate class that handles general calls.
+An example class can be found in the SwingJS distribution as src/javajs/async/AsyncDialog.java.
+Very simple modifications to the Java allows asynchronous operation using AsyncDialog. Here
+is a simple "do you want to close this frame" example, where you can see that what we have
+done is to set the reply into an ActionListener that is defined in the constructor of
+the AsyncDisplay object:
+
+// Original:
+//
+// private void promptQuit() {
+// int sel = JOptionPane.showConfirmDialog(null, PROMPT_EXIT, NAME, JOptionPane.YES_NO_OPTION);
+// switch (sel) {
+// case JOptionPane.YES_OPTION:
+// resultsTab.clean();
+// seqs.dispose();
+// if (fromMain) {
+// System.exit(0);
+// }
+// break;
+// }
+// }
+
+ private void promptQuitAsync() {
+ new AsyncDialog(new ActionListener() {
+
+ @Override
+ public void actionPerformed(ActionEvent e) {
+ int sel = ((AsyncDialog)e.getSource()).getOption();
+ switch (sel) {
+ case JOptionPane.YES_OPTION:
+ resultsTab.clean();
+ seqs.dispose();
+ if (fromMain) {
+ System.exit(0);
+ }
+ break;
+ }
+ }}).showConfirmDialog(null, PROMPT_EXIT, NAME, JOptionPane.YES_NO_OPTION);
+ }
+
+Very simple!
+
+
+native methods
+--------------
+
+The J2S compiler ignores all static native method declarations.
+Anything of this nature needs to be implemented in JavaScript if it is needed,
+using j2sNative blocks:
+
+/**
+ * @j2sNative
+ *
+ * var putYourJavaScriptCodeHere
+ *
+ */
+
+ Note that if you follow that directly with a {...} block, then
+ the javadoc code will run in JavaScript, and the {...} code will run in Java.
+
+
+key Focus
+---------
+
+As of June, 2019, the keyboard focus manager is fully implemented.
+The one catch is that JTextPane and JTextArea, which already consume
+VK_TAB in Java, cannot use CTRL-TAB to continue a tabbing cycle around
+the components in a window. Instead, CTRL-TAB is absorbed by the browser.
+
+
+LookAndFeel and UI Classes
+--------------------------
+
+SwingJS implements the native browser look and feel as swingjs.plaf.HTML5LookAndFeel.
+There are small differences between all look and feels -- MacOS, Windows, SwingJS.
+
+Expert developers know how to coerce changes in the UI by subclassing the UI for a
+component. This probably will not work in SwingJS.
+
+Note that LookAndFeel in Java usually determines canvas size in a Frame because
+different operating systems (Mac OS vs Windows vs HTML5) will have
+different edge sizes on their frames. If you want to ensure a component size,
+use getContentPane().setPreferredSize().
+
+
+System.exit(0) does not stop all processes
+------------------------------------------
+
+Although System.ext(int) has been implemented in JavaScript, it just closes the
+frames, stops all pending javax.swing.Timer objects in the queue, and runs any
+threads added using Runtime.getRuntime().addShutdownHook(Thread).
+It may not stop all "threads." So don't rely on that.
+Applications are responsible for shutting down prior to executing System.exit(0).
+
+
+myClass.getField not implemented
+--------------------------------
+
+java.lang.reflect.Field is implemented minimally. It is not
+certain that Field.getDeclaringClass() will work. If you just want a
+value of a field, you can do this:
+
+/**
+ *@j2sNative
+ *
+ * return myClass[name]
+ */
+
+But that is not a java.lang.reflection.Field object.
+
+
+"window" and other reserved JavaScript names
+--------------------------------------------
+
+No reserved top-level JavaScript name is allowed for a package name. So, for example,
+one must rename packages such as "window" or "document" to names such as "win" or "doc".
+
+reserved field and method names
+-------------------------------
+
+In order to minimize the chance of added SwingJS field and method names colliding with ones
+developers might use in subclassing Java classes, we have added U+79D8 (first character of Mandarin
+"secret") to the characters already disrecommended by Java documentation ("$" and "_"). The only problem
+would be if you use that character followed by certain English words in certain classes. For example
+\u79D8canvas for JComponents (in java.awt.JSComponent) and \u79D8byte (in java.io.File).
+
+qualified field and method names
+--------------------------------
+
+Method names in SwingJS are fully qualified, meaning two methods with the same Java name but different
+parameters, such as write(int) and write(double), must not have the same name in JavaScript. (In this
+case, we will have write$I and write$D.) However, in certain cases it may be desirable to leave the
+method names unqualified. In particular, when an interface actually represents a JavaScript object,
+the transpiler can leave a method name unqualified. The default situation for this is a class name
+includes ".api.js" (case-sensitive). This means that any method in any class in a package js within
+a package api, or any private interface js that has an outer interface api, will have all-unqualified
+methods. An example of this is swingjs.plaf.JSComboPopupList, which needs to communicate with a jQuery
+object directly using the following interface:
+
+ private interface api {
+
+ interface js extends JQueryObject {
+
+ abstract js j2sCB(Object options);
+
+ abstract Object[] j2sCB(String method);
+
+ abstract Object[] j2sCB(String method, Object o);
+
+ abstract Object[] j2sCB(String method, int i);
+
+ abstract int j2sCB(String OPTION, String name);
+
+ }
+ }
+
+Notice that all these variants of j2sCB() will call the same method in JavaScript by design.
+
+
+missing Math methods
+--------------------
+
+java.lang.Math is worked out, but some methods are missing, either because they
+involve long integer value that are inaccessible in JavaScript, or because I just
+didn't implement them. This is a result of continued Java development.
+It is easy enough to add these methods if you have the source. They go into j2sClazz.js,
+which is combined with other initial libraries into swingjs2.js by build_site.xml
+
+
+Component.getGraphics(), Graphics.dispose()
+-------------------------------------------
+
+Use of component.getGraphics() is discouraged in Java and in SwingJS.
+Specifically in SwingJS, any call to component.getGraphics() or
+BufferedImage.createGraphics() or Graphics.create(...) should be matched with graphics.dispose(),
+particularly when it is called outside the context of a paint(Graphics)
+call from the system.
+
+If you see your graphics scrolling down the page with each repaint,
+look for where you have used Component.getGraphics() and not Graphics.dispose().
+For example, this will definitely NOT work in SwingJS:
+
+ this.paint(getGraphics())
+
+and really should not work in Java, either, as it is technically a resource memory leak.
+
+Instead, if you really do not want to use repaint(), use this:
+
+ Graphics g = getGraphics();
+ paint(g);
+ g.dispose();
+
+
+
+Graphics.setClip()
+------------------
+
+The HTML5 canvas.clip() method is permanent. You can only reset the clip using
+save/restore. This is different from Java, where you can temporarily change it using
+
+ Shape oldClip = Graphics.getClip();
+ Graphics.setClip(newClip);
+ ...
+ Graphics.setClip(oldClip);
+
+If you need to do something like this, you must schedule the paints
+to not have overlapping clip needs.
+
+
+MAJOR ISSUES--for Bob and Udo within SwingJS
+============================================
+
+fonts
+-----
+
+Fonts and FontMetrics will all be handled in JavaScript. Font matching will
+not be exact, and composite (drawn) fonts will not be supported.
+
+SwingJS handles calls such as font.getFontMetrics(g).stringWidth("xxx") by
+creating a <div> containing that text, placing it in an obscure location on
+the page, and reading div.getBoundingClientRect(). This is a VERY precise
+value, but can be a pixel or two off from what Java reports for the same font.
+
+
+OS-dependent classes
+--------------------
+
+Static classes such as:
+
+ java.awt.Toolkit
+ java.awt.GraphicsEnvironment
+
+
+which are created using Class.forName are implemented using classes in the swingjs package.
+
+AWTAccessor is not implemented.
+
+
+AWT component peers and component "ui" user interfaces
+------------------------------------------------------
+
+ComponentPeer is a class that represents a native AWT component.
+Components with such peers are called "heavy-weight" components.
+They are expected to do the dirty work of graphics drawing.
+
+Java Swing implements peers only for JApplet, JDialog, JFrame, and JWindow.
+References to such objects have been removed, but clearly there must be
+some connection to similar DOM objects, even for "light-weight" components.
+
+
+
+MAJOR ISSUES--to be resolved by implementers
+============================================
+
+fonts
+-----
+
+Glyph/composite/outline fonts are not supported.
+
+
+
+threads
+-------
+
+Thread locking and synchronization are not relevant to JavaScript.
+Thus, anything requiring "notify.." or "waitFor.." could be a serious issue.
+
+All threading must be "faked" in JavaScript. Specifically not available is:
+
+ Thread.sleep()
+
+javax.swing.AbstractButton#doClick(pressTime) will not work, as it requires Thread.sleep();
+
+However, java.lang.Thread itself is implemented and used extensively.
+
+Methods thread.start() and thread.run() both work fine.
+
+For simple applications that use Thread.sleep() just to have a delay, as in a frame rate, for
+example, one can use javax.swing.Timer instead. That is fully implemented.
+
+Likewise, java.util.Timer can be replaced with no loss of performance with javax.Swing.Timer.
+Note that java.util.TimerTask is implemented, but it can also be replaced by an implementation of Runnable.
+
+task = new TimerTask(){....};
+t = new java.util.Timer();
+t.schedule(task, 0, 1);
+
+becomes
+
+task = new TimerTask(){....}; // or task = new Runnable() {...}
+t = new javax.swing.Timer(1, new ActionListener() {
+ @Override
+ public void actionPerformed(ActionEvent e) {
+ task.run();
+ }
+};
+t.setInitialDelay(0); // not particularly necessary
+t.start();
+
+In addition, SwingJS provides swingjs.JSThread, which can be subclassed
+if desired. This class allows simple
+
+ while(!interrupted()){
+ wait()
+ ...
+ }
+
+action through an asynchronous function run1(mode). For example:
+
+ protected void run1(int mode) {
+ try {
+ while (true)
+ switch (mode) {
+ case INIT:
+ // once-through stuff here
+ mode = LOOP;
+ break;
+ case LOOP:
+ if (!doDispatch || isInterrupted()) {
+ mode = DONE;
+ } else {
+ Runnable r = new Runnable() {
+ public void run() {
+ // put the loop code here
+ }
+ };
+ dispatchAndReturn(r);
+ if (isJS)
+ return;
+ }
+ break;
+ // add more cases as needed
+ case DONE:
+ // finish up here
+ if (isInterrupted())
+ return;
+ // or here
+ break;
+ }
+ } finally {
+ // stuff here to be executed after each loop in JS or at the end in Java
+ }
+ }
+
+image loading
+-------------
+- All image loading in SwingJS is synchronous. A MediaTracker call will immediately return "complete".
+ However, it still may take one system clock tick to fully load images. Thus, it is recommended that
+ images be preloaded in the static block of the applet if it is necessary that they be available in init().
+ This is only an issue if you are trying to access the pixel buffer of the image in JavaScript.
+
+- Applet.getImage(path, name) will return null if the image does not exist.
+
+- BufferedImage: only "support" imageType RGB and ARGB
+
+ -BH: This is a temporary edit, just to get us started. Certainly GRAY will be needed
+
+
+BigInteger and BigDecimal
+-------------------------
+
+java.math.BigInteger is fully supported; java.math.BigDecimal is roughed
+in and not fully tested (07/2019).
+
+Both classes present significant issues for JavaScript, as they are based in
+Java's 64-bit long for all their operations. Here is the JavaDoc note I added
+to BigInteger:
+
+ * SwingJS note: Because of the limitations of JavaScript with regard
+ * to long-integer bit storage as a double, this implementation drops
+ * the integer storage bit length to 24, giving 48 for long and leaving
+ * the last 16 bits clear for the exponent of the double number. This should
+ * not affect performance significantly. It does increase the storage
+ * size by about 33%. By bringing an "int" to 3 bytes, we can easily construct
+ * and use byte[] data intended for the original BitSet.
+
+"Easily" may be a bit strong there. This was a serious challenge.
+
+BigDecimal seems to run normally, but in order to do that, my hack involves
+reducing the size of an integer that is allowed to be stored as such and not
+in byte[] as a BigInteger. I'm sure there is a performance hit, but it does work.
+
+no format internationalization
+------------------------------
+
+For now, just en for number and date formatters
+
+no winding rules
+----------------
+
+ When filling a graphic, only nonzero winding rule is implemented in HTML5 Canvas2D.
+
+
+
+text-related field implementation
+---------------------------------
+
+Text fields are:
+
+JTextField (JavaScript <input type="text">)
+JTextArea (JavaScript <textarea>)
+JTextPane (JavaScript <div>)
+JEditorPane (JavaScript <div>)
+
+For the initial implementation, we don't implement infinite undo/redo, and the abstract
+document model is much less elaborate. Only PlainDocument (in the form of JSPlainDocument)
+is implemented. The Document returned by JTextField.getDocument() is a javax.swing.text.Document.
+
+All scrolling is handled by HTML5. javax.swing.AutoScroller is not implemented.
+public static methods .stop, .isRunning, .processMouseDragged require true Java threading
+and so are not implmented. javax.swing.text.View and its subclasses are not implemented.
+
+The JS document model does not allow two text fields to address the same underlying document.
+
+JavaScript is slightly different from Java in that the field value is changed asynchronously after
+the keypressed event, so Java actions that are keyed to KEY_PRESSED may not pick up the new
+key value even after SwingUtilities.invokeLater() is called. Thus, key pressed actions may need
+to be recorded after a key released event instead.
+
+Formatter/Regex limitations
+---------------------------
+
+Some browsers cannot process Regex "look-behind" process such as (?<=\W)
+java.util.regex.Matcher and Pattern use JavaScript's RegExp object rather than
+the native Java object. These are not identical. Only flags /igm are supported.
+Matcher.start(groupID) is not supported.
+
+java.util.Formatter will function correctly for all standard %... patterns.
+
+integer 1/0 == Infinity
+-----------------------
+
+1/0 in Java throws "java.lang.ArithmeticException: / by zero", but in JavaScript is just Infinity.
+
+
+
+Summary
+-------
+
+These are all the known limitations of SwingJS. We have not found any of these limitations
+to be show-stoppers. The primary issue for newcomers to SwingJS is having the source code.
+You must check that source code for all your library jar files is available or, if you
+choose, you will need to decompile those classes. We have used decompilation on some projects,
+and it works just fine. So, technically, all we really need are JAR/class files. But the
+source is by far superior. It's generally prettier, and it has the license information that
+may or may not be present with the JAR or class files. Use class files at your own risk.
+
+Bob Hanson
+2019.08.16
+
+
+Additional Issues
+-----------------
+
+Annotation is working for classes, methods, and fields (12/22/19). Method reflection, however,
+is limited. Interfaces do not expose their methods, as the transpiler does not actually transpile
+the interfaces themselves. And method reflection only includes annotated methods.
+
+java.util.concurrent is not fully elaborated. This package is rewritten to not actually use the
+memory handling capabilities of concurrency, which JavaScript does not have access to.
+
+System.getProperties() just returns a minimal set of properties.
+
+
-20200408084722
+20201222130550
java/awt/GraphicsConfiguration.js
java/awt/GraphicsDevice.js
java/awt/GraphicsEnvironment.js
+java/awt/Image.js
java/awt/image/ImageObserver.js
java/awt/Insets.js
java/awt/ItemSelectable.js
java/math/RoundingMode.js
java/net/URL.js
java/net/URLStreamHandlerFactory.js
+java/net/HttpURLConnection.js
+java/net/URLStreamHandler.js
+javax/net/ssl/HttpsUrlConnection.js
java/text/CharacterIterator.js
java/text/DecimalFormat.js
java/text/DecimalFormatSymbols.js
javajs/util/JSThread.js
javajs/util/Lst.js
javajs/util/PT.js
+javajs/util/Rdr.js
javajs/util/SB.js
-javax/net/ssl/HttpsUrlConnection.js
javax/swing/AbstractAction.js
javax/swing/AbstractButton.js
javax/swing/AbstractListModel.js
javax/swing/border/EmptyBorder.js
javax/swing/border/EtchedBorder.js
javax/swing/border/LineBorder.js
+javax/swing/border/TitledBorder.js
javax/swing/BorderFactory.js
javax/swing/BoundedRangeModel.js
javax/swing/BoxLayout.js
javax/swing/SortingFocusTraversalPolicy.js
javax/swing/SwingContainerOrderFocusTraversalPolicy.js
javax/swing/SwingDefaultFocusTraversalPolicy.js
+javax/swing/Icon.js
+javax/swing/ImageIcon.js
javax/swing/InputMap.js
javax/swing/JApplet.js
javax/swing/JButton.js
sun/awt/SunToolkit.js
sun/awt/WindowClosingListener.js
sun/awt/WindowClosingSupport.js
+sun/awt/image/DataStealer.js
+sun/awt/image/IntegerComponentRaster.js
+sun/awt/image/IntegerInterleavedRaster.js
+sun/awt/image/SunWritableRaster.js
sun/font/FontDesignMetrics.js
sun/swing/DefaultLookup.js
sun/swing/SwingLazyValue.js
sun/text/resources/FormatData.js
-sun/text/resources/FormatData_en.js
+sun/text/resources/en/FormatData_en.js
sun/util/resources/LocaleData.js
+sun/util/locale/BaseLocale.js
+sun/util/locale/LocaleUtils.js
+sun/util/locale/provider/LocaleProviderAdapter.js
+sun/util/locale/provider/LocaleDataMetaInfo.js
swingjs/a2s/A2SContainer.js
swingjs/a2s/A2SEvent.js
swingjs/a2s/A2SListener.js
swingjs/JSGraphics2D.js
swingjs/JSGraphicsConfiguration.js
swingjs/JSGraphicsEnvironment.js
+swingjs/JSImage.js
+swingjs/JSImagekit.js
swingjs/JSMouse.js
swingjs/JSNullComponentPeer.js
swingjs/JSScreenDevice.js
--- /dev/null
+Notes
+=====
+
+---IMPORTANT CHARACTER SET NOTE---
+
+It is critical that all development work in Java2Script
+be done in UTF-8. This means:
+
+- making sure your Eclipse project is set up for UTF-8 (not the Eclipse default?)
+- making sure your server can serve up UTF-8 by default for any browser-loaded files
+- making sure you don't edit a Java2Script class file or one of the site .js files
+ using a non-UTF-8 editor. It may replace non-Latin characters with "?" or garbage.
+- making sure that your web pages are delivered with proper headings indicating HTML5 and UTF-8
+
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="utf-8">
+
+Note that the DOCTYPE tag is critical for some browsers to switch into HTML5 mode. (MSIE?)
+
+
+
+
+In particular, the Mandarin character 秘 (mi; "secret") is used extensively throughout
+the SwingJS class files to distinguish j2s-specific fields and methods that must not
+ever be shadowed or overridden by subclasses. For example, we see in java.lang.Thread.java:
+
+ public static JSThread 秘thisThread;
+
+----------------------------------
+
+
+updated 12/6/2020 -- note about restrictions on long, including BitSet and Scanner
+updated 3/21/2020 -- adds note about HashMap, Hashtable, and HashSet iterator ordering
+updated 3/20/2020 -- adds note about interning, new String("xxx"), and "xxx"
+updated 2/26/2020 -- adds Graphics.setClip issue
+updated 12/22/19 -- additional issues
+updated 11/03/19 -- adds information about File.exists() and points to src/javajs/async
+updated 10/26/19 -- adds information about File.createTempFile()
+updated 8/16/19 -- minor typos and added summary paragraph
+updated 7/19/19 -- clarification that AWT and Swing classes are supported directly
+updated 5/13/19 -- Mandarin U+79D8 reserved character; Missing Math methods; int and long
+updated 5/10/19 -- adds a section on static issues in multi-(duplicate)-applet pages
+updated 1/4/19 -- nio
+updated 9/15/18 -- adds integer 1/0 == Infinity
+updated 7/24/18 -- most classes replaced with https://github.com/frohoff/jdk8u-jdk
+updated 6/5/17 -- reserved package name "window"
+updated 3/11/17 -- myClass.getField
+updated 3/7/17 -- overloading of JSplitPane.setDividerLocation
+updated 3/2/17 -- more indication of classes not implemented (KeyListener)
+
+=============================================================================
+SwingJS and OpenJDK 8+
+=============================================================================
+
+SwingJS implements a wide range of the Java language in JavaScript. The base
+version for this implementation is OpenJDK8. some classes are implemented using
+older source code, and there are some missing methods. For the most part, this is
+no real problem. You can add or modify any java class just be adding it as source
+in your project. Or (preferably) you can contact me, and I can get it into the
+distribution. Or (even more preferably) you can do that via a patch submission.
+
+=================
+DESIGN PHILOSOPHY
+=================
+
+The java2script/SwingJS design goal is to recreate a recognizable, easily debuggable
+equivalent in JavaScript for as much of Java as practical. This means, for example,
+that one can call in JavaScript
+
+ new java.util.Hashtable()
+
+and for all practical purposes it will appear that Java is running.
+
+
+Method and Field Disambiguation
+-------------------------------
+
+SwingJS has no problem with the overloading of methods, for example:
+
+ public void print(int b);
+ public void print(float b);
+
+JavaScript does not allow overloading of methods, and the common practice in
+Java of naming a field the same as a method -- isAllowed and isAllowed() -- is
+not possible in JavaScript. As a result, SwingJS implements "fully-qualified"
+method names using "$" parameter type separation. Thus, these methods in SwingJS
+will be referred to as print$I and print$F. The rules for this encoding are
+relatively simple:
+
+1. The seven primitive types in Java are encoded $I (int), $L (long), $F (float),
+$D (double), $B (byte) $Z (boolean), and $H (short).
+
+2. String and Object are encoded as $S and $O, respectively.
+
+3. "java_lang_" is dropped for all other classes in the java.lang package (as in Java).
+ For example: $StringBuffer, not $java_lang_StringBuffer
+
+4. All other classes are encoded as
+
+ "$" + Class.getName().replace(".","_")
+
+For example, in Java we see:
+
+ public void equals(Object o) {...}
+
+Whereas in SwingJS we have:
+
+ Clazz.newMeth(C$, 'equals$O', function (o) {...}
+
+And
+
+ this.getContentPane().add(bar, "North");
+
+becomes
+
+ this.getContentPane$().add$java_awt_Component$O(bar, "North");
+
+5. Arrays are indicated with appended "A" for each level. So
+
+ setDataVector(Object[][] dataVector, Object[] columnIdentifiers)
+
+becomes
+
+ setDataVector$OAA$OA(dataVector, columnIdentifiers)
+
+(It is recognized that this design does introduce a bit of ambiguity, in that
+ in principal there could be user class named XA and X in the same package,
+ and methods a(X[]) and a(XA) in the same class that cannot be distinguished.
+ The benefit of this simple system, however, triumphed over the unlikelyhood
+ of that scenario.) The transpiler could be set to flag this possibility.
+
+6. Constructors are prepended with "c$". So
+
+ public JLabel(String text) {...}
+
+becomes:
+
+ Clazz.newMeth(C$, 'c$$S', function (text) {...});
+
+Field disambiguation involves prepending. In Java, a class and its subclass
+can both have the same field name, such as
+
+ boolean visible;
+
+When this happens, it is called "shadowing", and though not recommended, Java allows
+it. The Java2Script transpiler will prepend such shadowing fields with "$" so that the
+subclass instance has both "visible" (for use in its methods inherited from its
+superclass) and "$visible" (for its own methods). Thus, we might see in Java:
+
+ this.visible = super.visible;
+
+while in SwingJS we will see:
+
+ this.$visible=this.visible;
+
+since JavaScript does not have the "super" keyword.
+
+
+
+Parameterless methods such as toString() are appended with "$" to become toString$().
+The one exception to this rule is private methods, which are saved in (truly) private
+array in the class (and are not accessible by reflection). Private parameterless
+methods retain their simple Java name, since they cannot conflict with field names.
+
+This renaming of methods has a few consequences, which are discussed more fully below.
+See particularly the section on "qualified field and method names", where it is described
+how you can use packages or classes or interfaces with ".api.js" in them to represent JavaScript
+objects for which all method names are to be left unqualified. Note that it is not
+possible to cherry-pick methods to be unqualified; only full packages, classes or
+interfaces can hold this status.
+
+The swingjs.api.js package in particular contains a number of useful interfaces that
+you can import into your project for JavaScript-specific capabilities.
+
+
+Applet vs. Application
+----------------------
+
+One of the very cool aspects of SwingJS is that it doesn't particularly matter if a browser-based
+Java app is an "applet" or an "application". We don't need JNLP (Java Network Launch Protocol)
+because now we can just start up any Java application in a browser just as easily as any applet.
+The associative array that passes information to the SwingJS applet (information that formerly
+might have been part of the APPLET tag, such as width, height, and codebase, always referred to
+in our writing as "the Info array") allows the option to specify the JApplet/Applet "code"
+class or the application "main" class. Either one will run just fine.
+
+
+Performance
+-----------
+
+Obviously, there are limitations. One is performance, but we have seen reproducible
+performance at 1/6 - 1/3 the speed of Java. Achieving this performance may require
+some refactoring of the Java to make it more efficient in both Java and JavaScript.
+"for" loops need to be more carefully crafted; use of "new" and "instanceof" need to be
+minimized in critical areas. Note that method overloading -- that is, the same method name
+with different parameters, such as read(int) and read(byte) -- is no longer any problem.
+
+
+Threads
+-------
+
+Although there is only a single thread in JavaScript, meaning Thread.wait(), Thread.sleep(int) and
+Thread.notify() cannot be reproduced, we have found that this is not a serious limitation.
+For example, javax.swing.Timer() works perfectly in JavaScript. All it means is that threads
+that use sleep(int) or notify() must be refactored to allow Timer-like callbacks. That is,
+they must allow full exit and re-entry of Thread.run(), not the typical while/sleep motif.
+
+The key is to create a state-based run() that can be exited and re-entered in JavaScript.
+
+
+Static fields
+-------------
+
+Final static primitive "constant" fields (String, boolean, int, etc.) such as
+
+static final int TEST = 3;
+static final String MY_STRING = "my " + "string";
+
+are converted to their primitive form automatically by the Eclipse Java compiler
+and do not appear in the JavaScript by their names.
+
+Other static fields are properties of their class and can be used as expected.
+
+Note, however, that SwingJS runs all "Java" code on a page in a common "jvm"
+(like older versions of Java). So, like the older Java schema, the JavaScript
+equivalents of both applets and applications will share all of their static
+fields and methods. This includes java.lang.System.
+
+Basically, SwingJS implementations of Java run in a browser page-based sandbox
+instead of an applet-specific one.
+
+In general, this is no problem. But if we are to implement pages with
+multiple applets present, we must be sure to only have static references
+that are "final" or specifically meant to be shared in a JavaScript
+environment only (since they will not be shared in Java).
+
+A simple solution, if static non-constant references are needed, is to attach the
+field to Thread.currentThread.threadGroup(), which is an applet-specific reference.
+Be sure, if you do this, that you use explicit setters and getters:
+
+For example,
+
+private static String myvar;
+
+...
+
+public void setMyVar(String x) {
+ ThreadGroup g = Thread.currentThread().threadGroup();
+ /**
+ * @j2sNative g._myvar = x;
+ *
+ */
+ {
+ myvar = x;
+ }
+}
+
+public String getMyVar() {
+ ThreadGroup g = Thread.currentThread().threadGroup();
+ /**
+ * @j2sNative return g._myvar || null;
+ *
+ */
+ {
+ return myvar;
+ }
+}
+
+ in Java will get and set x the same in JavaScript and in Java.
+
+
+A convenient way to do this in general is to supply a singleton class with
+explicitly private-only constructors and then refer to it in Java and in JavaScript
+instead of using static field, referring to myclass.getIntance().xxx instead of
+myclass.xxx in Java (and JavaScript).
+
+This was done extensively in the Jalview project. See jalview.bin.Instance.
+
+
+Helper Packages -- swingjs/ and javajs/
+---------------------------------------
+
+The SwingJS library is the swingjs/ package. There are interfaces that may be of assistance
+in swingjs/api, but other than that, it is not recommended that developers access classes in
+this package. The "public" nature of their methods is really an internal necessity.
+
+In addition to swingjs/, though, there are several useful classes in the javajs/ package
+that could be very useful. This package is a stand-alone package that can be
+cloned in any Java project that also would be great to have in any JavaScript project
+-- SwingJS-related or not. Functionality ranges from reading and writing various file
+formats, including PDF, BMP, PNG, GIF, JPG, JSON, ZIP, and CompoundDocument formats.
+
+A variety of highly efficient three- and four-dimensional point, vector, matrix, and
+quaternion classes are included, as they were developed for JSmol and inherited from that
+project.
+
+Of particular interest should be javajs/async/, which includes
+
+javajs.async.Async
+javajs.async.AsyncColorChooser
+javajs.async.AsyncDialog
+javajs.async.AsyncFileChooser
+
+See javajs.async.Async JavaDoc comments for a full description of
+these useful classes.
+
+
+Modal Dialogs
+-------------
+
+Although true modal dialogs are not possible with only one thread, a functional equivalent --
+asynchronous modal dialogs -- is relatively easy to set up. All the JOptionPane dialogs will
+return PropertyChangeEvents to signal that they have been disposed of and containing the results.
+See below and classes in the javajs.async package.
+
+
+Native calls
+------------
+
+Native calls in Java are calls to operating system methods that are not in Java. JavaScript
+has no access to these, of course, and they must all be replaced by JavaScript equivalents.
+Fortunately, they are not common, and those that are present in Java (for example, in calculating
+checksums in ZIP file creation) are at a low enough level that most developers do not utilize them
+or do not even have access to them. All native calls in Java classes have been replaced by
+Java equivalents.
+
+
+Swing GUI Peers and UIClasses
+-----------------------------
+
+One of the biggest adaptations introduced in SwingJS is in the area of the graphical
+user interface. The issue here is complex but workable. In Java there are two background
+concepts -- the Component "peer" (one per "heavy-weight" component, such as a Frame) and the
+component "uiClass" (one per component, such as JButton or JTextField).
+
+Peers are native objects of the operating system. These are the virtual buttons and text areas
+that the user is interacting with at a very base level. Their events are being passed on to
+Java or the browser by the operating system. UI classes provide a consistent "look and feel"
+for these native objects, rendering them onto the native window canvas and handling all
+user-generated events. They paint the borders, the backgrounds, the highlights, of every
+control you see in Java. There is one-to-one correspondence of Swing classes and UI classes.
+Setting the Look and Feel for a project amounts to selecting the directory from which to draw
+these UI classes. The UI classes can be found in the javax.swing.plaf ("platform look and feel")
+package.
+
+Early on in the development of SwingJS, we decided not to fully reproduce the painfully detailed
+bit-by-bit painting of controls as is done in Java. Instead, we felt it was wiser to utilize the standard
+HTML5 UI capabilities as much as possible, using DIV, and INPUT especially, with extensive use
+of CSS and sometimes jQuery (menus, and sliders, for example). Thus, we have created a new
+set of UIs -- the "HTML5 Look and Feel". These classes can be found in swingjs.plaf. Besides being
+more adaptable, this approach allows far more versatility to SwingJS developers, allowing them
+to modify the GUI to suit their needs if desired.
+
+In SwingJS, since we have no access to native peers except through the browser DOM,
+it seemed logical to merge the peer and UI idea. So instead of having one peer per heavy-weight control and
+one UI class instance for each control type, we just have one UI class instance per control, and
+that UI class instance is what is being referred to when a "peer" is notified.
+
+In some ways this is a throw back to when all of Swing's components were subclasses of
+specific AWT components such as Button and List. These "heavy-weight components" all had their
+own individual native peers and thus automatically took on the look and feel provided by the OS.
+Later Swing versions implemented full look and feel for all peers, leaving only JDialog, JFrame,
+and a few other classes to have native peers. But in SwingJS we have again a 1:1 map of component
+and UI class/peer instance.
+
+The origin of most issues (read "bugs") in relation to the GUI will probably be found in the
+swingjs.plaf JSxxxxUI.java code.
+
+
+Swing-only Components -- no longer an issue
+-------------------------------------------
+
+Swing was introduced into Java well after the Java Abstract Window Toolkit (AWT) was well
+established. As such, its designers chose to allow AWT controls such as Button and List to be used
+alongside their Swing counterparts JButton and JList. Reading the code, it is clear that this
+design choice posed a huge headache for Swing class developers.
+
+For SwingJS, we decided from the beginning NOT to allow this mixed-mode programming and
+instead to require that all components be Swing components.
+
+However, this is no longer an issue. All AWT components in SwingJS are now subclasses of
+javax.swing.JComponent. So far, we have found no problem with this.
+
+
+The a2s Adapter Package
+-----------------------
+
+Originally, we thought that we would restrict ourselves to JApplets only. That is, only
+Swing-based applets. But as we worked, we discovered that there are a lot of great
+applets out there that are pre-Swing pure-AWT java.applet.Applet applets. Our problem was
+that we also wanted it to be possible to quickly adapt these applets to JavaScript as well.
+
+The solution turned out to be simple: Write a package (a2s) that recreates the interface for
+non-Swing components as subclasses of Swing components. Thus, a2s.Button subclasses javax.swing.JButton
+but also accepts all of the methods of java.awt.Button. This works amazingly well, with a few
+special adaptations to the core javax.swing to be "AWT-aware." All AWT components now subclass
+a2s components, which in turn subclass JComponents. So no changes in code are necessary. We have
+successfully transpiled over 500 applets using this strategy. (Kind of surprising, actually, that
+the original Java developers did not see that option. But we have a hindsight advantage here.)
+
+
+Working with Files
+==================
+
+Simple String file names are not optimal for passing information about
+read files within SwingJS applications.
+
+All work with files should either use Path or File objects exclusively.
+These objects, after a file is read or checked for existence, will already
+contain the file byte[] data. Doing something like this:
+
+File f = File("./test.dat");
+boolean isOK = f.exists();
+
+will load f with its byte[] data, if the file exists.
+
+But if after that, we use:
+
+File f2 = new File(f.getAbsolutePath());
+
+f2 will not contain that data. Such copying should be done as:
+
+File f2 = new File(f);
+
+in which case, the byte[] data will be transferred.
+
+
+SwingJS uses the following criteria to determine if File.exists() returns true:
+
+(1) if this File object has been used directly to read data, or
+(2) if reading data using this File object is successful.
+
+Note that you cannot check to see if a file exists before input or if it
+was actually written or if it already exists prior to writing in SwingJS.
+
+Thus, you should check each use of file.exists() carefully, and if necessary, provide a J2sNative
+block that gives an appropriate "OK" message, for example:
+
+(/** @j2sNative 1 ? false : */ outputfile.exits())
+
+or
+
+(/** @j2sNative 1 ? true : */ inputfile.exits())
+
+Temporary files can be created in SwingJS. SwingJS will maintain a pseudo-filesystem for files
+created with File.createTempFile(). This is useful in that closure of writing to a temporary file
+does not generate a pseudo-download to the user's machine.
+
+
+UNIMPLEMENTED CLASSES BY DESIGN
+===============================
+
+The SwingJS implementation of the following classes are present
+in a way that gracefully bypasses their functionality:
+
+accessibility
+security
+serialization
+
+
+
+TODO LIST FOR UNIMPLEMENTED CLASSES
+===================================
+
+JEditorPane (minimal implementation) - DONE 12/2018; some issues still
+JSplitPane - DONE 8/2018
+JTabbedPane - DONE 10/2018
+JTree - done 12/2019
+
+
+MINOR ISSUES--required some rewriting/refactoring by Bob and Udo
+================================================================
+
+Thread.currentThread() == dispatchThread
+
+
+MINOR ISSUES--requiring some rewriting/refactoring outside of SwingJS
+=====================================================================
+
+See below for a full discussion.
+
+Restrictions on long
+Restriction on BitSet and Scanner
+HashMap, Hashtable, and HashSet iterator ordering
+interning, new String("xxx") vs "xxx"
+Names with "$" and "_"
+positive integers do not add to give negative numbers
+ArrayIndexOutOfBounds
+java.awt.Color
+native methods
+javax.swing.JFileDialog
+key focus
+LookAndFeel and UI Classes
+System.exit(0) does not stop all processes
+list cell renderers must be JComponents
+myClass.getField not implemented
+"window" and other reserved JavaScript names
+reserved field and method names
+qualified field and method names
+missing Math methods
+Component.getGraphics(), Graphics.dispose()
+Graphics.setClip()
+
+MAJOR ISSUES--for Bob and Udo within SwingJS
+============================================
+
+fonts
+OS-dependent classes
+AWT component peers
+some aspects of reflection
+
+MAJOR ISSUES--to be resolved by implementers
+============================================
+
+fonts
+threads
+modal dialogs
+image loading
+BigDecimal not fully implemented
+no format internationalization
+no winding rules
+text-related field implementation
+Formatter/Regex limitations
+integer 1/0 == Infinity
+
+========================================================================
+
+DISCUSS
+=======
+
+Table row/col sorter needs checking after removal of java.text.Collator references
+
+I had to move all of SunHints class to RenderingHints, or the
+two classes could not be loaded. Shouldn't be a problem, I think. The sun classes are
+not accessible to developers in Java anyway, since they are generally package private.
+
+==========================================================================
+
+//////////////////////////////////////////////////////////////////////////////
+
+UNIMPLEMENTED CLASSES
+=====================
+
+accessibility
+-------------
+
+All Accessibility handling has been commented out to save the download footprint.
+This removes the need for sun.misc.SharedSecrets as well.
+Nothing says we could not implement accessibility. We just didn't.
+
+
+security
+--------
+
+All JavaScript security is handled by the browser natively.
+Thus, Java security checking is no longer necessary, and
+java.security.AccessController has been simplified to work without
+native security checking.
+
+Note that private methods in a class are REALLY private.
+
+
+serialization
+-------------
+
+All serialization has been removed. It was never very useful for Swing anyway,
+because one needs exactly the same Java version to save and restore serialized objects.
+
+
+keyboard accelerators and mnemonics
+-----------------------------------
+
+This work was completed in the spring of 2019. Note that in a browser, some
+key strokes, particularly CTRL-keys, are not available. Bummer.
+
+
+MINOR ISSUES--required some rewriting/refactoring by Bob and Udo
+================================================================
+
+
+Thread.currentThread() == dispatchThread
+----------------------------------------
+
+changed to JSToolkit.isDispatchThread()
+
+
+MINOR ISSUES--requiring some rewriting/refactoring outside of SwingJS
+=====================================================================
+
+restrictions on long
+--------------------
+
+Java's 64-bit long type is not supported in JavaScript. There is no Int64Array in JavaScript,
+and 0x20000000000000 + 1 evaluates to 0x20000000000000, not 0x20000000000001.
+(Likewise, -0x20000000000000 - 1 is left unchanged.)
+
+The largest "integer" value in JavaScript is 9007199254740991 (9.007199254740991E13, or 0x1FFFFFFFFFFFFFF).
+Effectively, you get to use only 53 bits of the long, not 64. Trying to set a long larger than
+0x1FFFFFFFFFFFFFF or smaller than -0x1FFFFFFFFFFFFFF will result in a NumberFormatException.
+
+The transpiler handles conversion to long the same as Java for all cases other than from double.
+
+For small double values, there is no problem, and, in fact, this is a known trick used to round
+doubles and floats toward zero:
+
+double d;
+d = (long) 3.8;
+assert(d == 3);
+d = (long) -3.8;
+assert(d == -3);
+
+SwingJS will evaluate (long) d as 0 for d > 9007199254740991
+or d < -9007199254740991, same as Java returns for Double.NaN.
+So, in Java we have:
+
+ assert(((long) Double.NaN) == 0);
+ assert(((int) Double.NaN) == 0);
+ assert(((long) Float.NaN) == 0);
+ assert(((int) Float.NaN) == 0);
+
+and also, in JavaScript only, we also have:
+
+ double d = 0x2000000000000L;
+ assert(((long) d) == 0);
+
+
+restrictions on BitSet and Scanner
+----------------------------------
+
+Because of the issue of long being only 53 bits, any time a method returns a long value, considerations must
+be made as to whether this will work in JavaScript. In particular, BitSet and Scanner have issues.
+
+In SwingJS, java.util.BitSet has been implemented as a 32-bit integer-based bitset. This was no problem in
+Java 6, but starting with Java 7, a method was added to BitSet that allows for the extraction of the
+underlying long[] word data. This is not work in JavaScript. Instead, SwingJS java.util.Bitset.toLongArray() will deliver
+32-bit int[] data.
+
+SwingJS Scanner has hasNextLong() and nextLong(), and although it will scan through long numbers,
+Scanner will choke on long numbers greater than the JavaScript 53-bit limit. hasNextLong() will
+return false, and nextLong() will throw an InputMismatchException triggered by the NumberFormatException
+thrown by Long.parseLong().
+
+
+HashMap, Hashtable, and HashSet iterator ordering
+-------------------------------------------------
+
+In Java, iterators for HashMap, Hashtable, and HashSet do not guarantee any particular order.
+From the HashMap documentation for Java 8:
+
+ This class makes no guarantees as to the order of the map; in particular, it does not
+ guarantee that the order will remain constant over time.
+
+Likewise, for HashSet (because it is simply a convenience method for HashMap<Object,PRESENT>:
+
+ [HashSet] makes no guarantees as to the iteration order of the set.
+
+JavaScript's Map object is different. It is basically a LinkedHashMap, so it guarantees iteration
+in order of object addition.
+
+Starting with java2script 3.2.9.v1, these classes use the JavaScript Map object rather than hash codes
+whenever all keys are strictly of JavaScript typeof "string". If any key is introduced that is not a string, the
+implementation falls back to using hash codes, the same as Java.
+
+Note strings created using new String("xxxx") are NOT typeof "string"; they are typeof "object".
+
+The result is significantly faster performance (3-12 x faster) than originally, and up to 3 x faster
+performance in JavaScript than in Java itself. Right. Faster than Java.
+
+The JavaScript Map implementation is implemented UNLESS the constructor used is the one that
+specifies both initial capacity and load factor in their constructor. Thus,
+
+new Hashtable()
+new HashMap()
+new HashMap(16)
+new HashSet()
+
+all use the JavaScript Map. But
+
+new Hashtable(11, 0.75f)
+new HashMap(16, 0.75f)
+new HashSet(16, 0.75f)
+
+do not.
+
+This design allows for opting out of the JavaScript Map use in order to retain the exact behavior of
+iterators in JavaScript as in Java.
+
+
+interning, new String("xxx") vs "xxx"
+-------------------------------------
+
+Note that the following are true in JavaScript:
+
+typeof new String("xxxx") == "object"
+typeof "xxxx" == "string"
+var s = "x";typeof ("xxx" + s) == "string"
+
+There is no equivalence to this behavior in Java, where a String is a String is a String.
+
+Be aware that SwingJS does not always create a JavaScript String object using JavaScript's
+new String(...) constructor. It only does this for Java new String("xxxx") or new String(new String()).
+
+In all other cases, new String(...) (in Java) results in a simple "xxxx" string in JavaScript.
+That is, it will be JavaScript typeof "string", not typeof "object".
+
+The reason for this design is that several classes in the Java core use toString()
+methods that return new String(), and those classes that do that would cause a JavaScript error
+if implicitly stringified if new String() returned a JavaScript String object.
+
+This is fine in JavaScript
+
+test1 = function() { return { toString:function(){ return "OK" } } }
+"testing" + new test1()
+>> "testingOK"
+
+But for whatever reason in JavaScript:
+
+test2 = function() { return { toString:function(){ return new String("OK") } } }
+"testing" + new test2()
+>> Uncaught TypeError: Cannot convert object to primitive value
+
+The lesson here is never to use
+
+ return new String("...");
+
+in a Java toString() method. In Java it will be fine; in JavaScript it will also be fine as long as
+that method is never called in JavaScript implicitly in the context of string concatenation.
+
+A note about interning. Consider the following six Java constructions, where we have a == "x";
+
+"xxx"
+"xx" + "x"
+new String("xxx").intern()
+
+new String("xxx")
+"xx" + a.toString()
+"xx" + a
+
+All six of these will return java.lang.String for .getClass().getName().
+However, the first three are String literals, while the last three are String objects.
+Thus:
+ "xxx" == "xxx"
+ "xxx" == "xx" + "x"
+ "xxx" == new String("xxx").intern()
+
+but none of the other three are equivalent to "xxx" or each other:
+
+ "xxx" != new String("xxx")
+ "xxx" != "xx" + a.toString()
+ "xxx" != "xx" + a
+ new String("xxx") != new String("xxx")
+ "xx" + a != new String("xxx")
+
+etc.
+
+As in Java, in SwingJS, all of the following Java assertions pass as true:
+
+ assert("xxx" == "xx" + "x");
+ assert("xxx" == ("xx" + a).intern());
+ assert("xxx" === new String("xxx").intern());
+
+and both of these do as well:
+
+ assert(new String("xxx") != "xxx");
+ assert(new String("xxx") != new String("xxx"));
+
+But the following two fail to assert true:
+
+ assert("xxx" != "xx" + a);
+ assert("xxx" != "xx" + a.toString());
+
+because in JavaScript, both of these right-side expressions evaluate to a simple "interned" string.
+
+In Java, however, these assertions are true because Java implicitly "boxes" String
+concatentaion as a String object, not a literal.
+
+Most of us know not to generally use == with Strings unless they are explicitly interned.
+Where this problem may arise, though, is in IdentityHashMap, which compares objects using
+System.identityHashCode(), which is not the same for different objects or their string literal equivalents.
+
+My recommendation, if you need to use IdentityHashMap with strings is to always use an explicit String.intern()
+for any keys -- unless you really want to keep every string as separate keys even if they are the same sequence,
+in which case, use new String(). This will work in Java and in JavaScript.
+
+Be aware when working with strings that come from SwingJS and are being used by other JavaScript modules
+that those that are String objects will return "object" for the JavaScript typeof operator, not "string".
+
+The easy way to ensure this is no problem is to concatenate strings with "" to force immediate interning:
+
+ var x = aJavaObject.getString() + "";
+
+unless you are certain that the string is being returned is a raw JavaScript string.
+
+Names with "$" and "_"
+----------------------
+
+For the most part, this should be no problem.
+
+Note that the use of $ and _ in Java field names has always been discouraged:
+[https://docs.oracle.com/javase/tutorial/java/nutsandbolts/variables.html]
+
+ You may find some situations where auto-generated names will contain the dollar sign,
+ but your variable names should always avoid using it. A similar convention
+ exists for the underscore character; while it's technically legal to begin your
+ variable's name with "_", this practice is discouraged.
+
+Some impacts of transpiling method names with full qualification:
+
+1) SwingJS will introduce fields that start with $ or _. These will not conflict
+ if the above convention is followed.
+
+2) Fields that have the same Java name as a method are not an issue.
+
+3) Fields that have a Java name with $ that matches a transpiled method name,
+ such as toString$, will need to be refactored in Java to not have that name collision.
+
+4) Fields in a subclass that have the same name as private fields in a superclass
+ represent a name collision, because the superclass method needs to call its private
+ field even if invoked from a subclass. The solution was to modify the subclass field
+ name using one or more prepended $.
+
+5) Use of Class.getDeclaredMethods() reflection will return Method objects having the transpiled
+ name, not the Java name. This could require some j2sNative adjustment
+ to strip the $... parameters from the name if that is needed.
+
+6) Use of Method.getParameterTypes() should work fine, provided class names
+ do not contain "_". This is because the transpiler converts "." to "_" when
+ creating the fully qualified JavaScript name.
+
+
+positive integers do not add to give negative numbers
+-----------------------------------------------------
+
+In Java, the following is true:
+
+ 2000000000 + 2000000000 == -294967296
+
+But in SwingJS, that will be 4000000000. So, for example, the following
+strategy will fail in SwingJS:
+
+ int newLength = lineBuf.length * 2;
+ if (newLength < 0) {
+ newLength = Integer.MAX_VALUE;
+ }
+
+"-1" in JavaScript is not 0xFFFFFFFF.
+
+And one must take care to not compare a negative number with a 32-bit mask. So
+
+(b & 0xFF000000) == 0xFF000000
+
+is true in Java for (int) b = -1, but is false in JavaScript, because 0xFF000000 is 4278190080,
+while (-1 & 0xFF000000) is, strangely enough, -16777216, and, in fact,
+
+(0xFF000000 & 0xFF000000) != 0xFF000000
+
+because -16777216 is not 4278190080.
+
+The fix is that one must compare similar operations:
+
+if ((b & 0xFF000000) == (0xFF000000 & 0xFF000000)) .....
+
+Importantly, the JavaScript Int32Array does behave properly. From
+the Firefox developer console:
+
+>> x = new Int32Array(1)
+<- Int32Array(1) [ 0 ]
+>> x[0] = 4000000000
+<- 4000000000
+>> x[0]
+<- -294967296
+
+Notice that, perhaps unexpectedly, the following two constructs produce
+different results in JavaScript:
+
+x = new Int32Array(1);
+b = x[0] = 4000000000;
+
+(b will be 4000000000)
+
+and
+
+x = new Int32Array(1);
+x[0] = 4000000000;
+b = x[0];
+
+(b will be -294967296)
+
+
+SwingJS leverages array typing to handle all byte and short arithmetic so as
+to ensure that any byte or short operation in JavaScript does give the same
+result in Java. The design decision to not also do this with integer math was
+a trade-off between performance and handling edge cases.
+
+
+ArrayIndexOutOfBounds
+---------------------
+
+You cannot implicitly throw an ArrayIndexOutOfBoundsException in JavaScript.
+JavaScript will simply return "undefined", not throw an Exception. So:
+
+boolean notAGoodIdeaIsOutOfBounds(String[] sa, int i) {
+ try {
+ return (sa[i] == sa[i]);
+ } catch (ArrayIndexOutOfBoundsException e) {
+ return false;
+ }
+}
+
+will work in Java but not in JavaScript. Code should not depend upon this sort
+of trap anyway, if you ask me.
+
+Throwable vs Error vs Exception
+-------------------------------
+
+True JavaScript errors are trapped as Throwable, whereas you can still trap
+Error and Exception as well. So if you want to be sure to catch any JavaScript
+error, use try{}catch (Throwable t){}, not try{}catch (Exception e){}.
+
+j
+ava.awt.Color
+--------------
+
+ColorSpace: only "support" CS_sRGB.
+
+ TODO -- any volunteers??
+
+
+javax.swing.JFileDialog
+-----------------------
+
+HTML5 cannot expose a file reading directory structure. But you certainly
+can still do file reading and writing. It just works a little differently.
+It's a simple modification:
+
+ b = new JButton("FileOpenDialog");
+ b.addActionListener(new ActionListener() {
+
+ @Override
+ public void actionPerformed(ActionEvent e) {
+ JFileChooser fc = new JFileChooser();
+ Test_Dialog.this.onDialogReturn(fc.showOpenDialog(Test_Dialog.this));
+ // Java will wait until the dialog is closed, then enter the onDialogReturn method.
+ // JavaScript will exit with NaN immediately, and then call back with its actual value
+ // asynchronously.
+ }
+
+ });
+
+ public void onDialogReturn(int value) {
+ if (value != Math.floor(value))
+ return; // in JavaScript, this will be NaN, indicating the dialog has been opened
+ // If we are here, the dialog has closed, in both Java and JavaScript.
+ System.out.println("int value is " + value);
+ }
+
+
+ @Override
+ public void propertyChange(PropertyChangeEvent event) {
+ Object val = event.getNewValue();
+ String name = event.getPropertyName();
+ System.out.println(name);
+ switch (event.getSource().getClass().getName()) {
+ case "javax.swing.JOptionPane":
+ switch (name) {
+ case "inputValue":
+ onDialogReturn(val);
+ return;
+ case "value":
+ if (val instanceof Integer)
+ onDialogReturn(((Integer) val).intValue());
+ else
+ onDialogReturn(val);
+ return;
+ }
+ break;
+ case "javax.swing.ColorChooserDialog":
+ switch (name) {
+ case "SelectedColor":
+ onDialogReturn(val);
+ return;
+ }
+ break;
+ case "javax.swing.JFileChooser":
+ switch (name) {
+ case "SelectedFile":
+ File file = (File) val;
+ byte[] array = (val == null ? null : /** @j2sNative file.秘bytes || */
+ null);
+ onDialogReturn("fileName is '" + file.getName() + "'\n\n" + new String(array));
+ return;
+ }
+ break;
+ }
+ System.out.println(
+ event.getSource().getClass().getName() + " " + event.getPropertyName() + ": " + event.getNewValue());
+ }
+
+
+Developers are encouraged to create a separate class that handles general calls to JFileDialog.
+An example class can be found in the SwingJS distribution as
+
+/sources/net.sf.j2s.java.core/src/javajs/async/AsyncFileChooser.java.
+
+
+javax.swing.JOptionPane dialogs
+-------------------------------
+
+For this action to work, the parentComponent must implement
+propertyChangeListener, and any call to JOptionPanel should allow for
+an asynchronous response, meaning that there is no actionable code following the
+call to the dialog opening.
+
+In addition, for compatibility with the Java version, implementation should
+wrap the call to getConfirmDialog or getOptionDialog in a method call to
+handle the Java:
+
+onDialogReturn(JOptionPane.showConfirmDialog(parentFrame,
+messageOrMessagePanel, "title", JOptionPane.OK_CANCEL_OPTION));
+
+Then parentFrame.propertyChange(event) should also call onDialogReturn.
+
+This will then work in both Java and JavaScript.
+
+Note that there is an int and an Object version of onDialogReturn().
+
+
+In JavaScript:
+
+The initial return from JOptionPane.showConfirmDialog and showMessageDialog
+will be (SwingJS) JDialog.ASYNCHRONOUS_INTEGER (NaN), testable as an impossible
+Java int value using ret != -(-ret) if the parent implements PropertyChangeListener, or -1
+(CLOSE_OPTION) if not.
+
+For showOptionDialog (which returns Object) or showInputDialog (which returns
+String), the initial return will be (SwingJS) JDialog.ASYNCHRONOUS_OBJECT, testable as
+((Object) ret) instanceof javax.swing.plaf.UIResource if the parent implements
+PropertyChangeListeneer, or null if not.
+
+The second return will be the desired return.
+
+In Java:
+
+The initial return will be the one and only modal final return.
+
+
+
+For full compatibility, The calling method must not continue beyond this
+call.
+
+All of the standard Java events associated with Components are also
+available.
+
+Certain fall back mechanisms are possible, where onReturn does not exist, but
+only for the following cases:
+
+
+For showMessageDialog, for WARNING_MESSAGE and ERROR_MESSAGE, a simple
+JavaScript alert() is used, returning 0 (OK_OPTION) or -1 (CLOSED_OPTION).
+
+For showInputDialog, if the message is a string, a simple JavaScript prompt()
+with input box is used, returning the entered string or null.
+
+For showConfirmDialog, a simple JavaScript confirm() is used, in which case:
+
+for YES_NO_OPTION: YES_OPTION or NO_OPTION
+
+for YES_NO_CANCEL_OPTION: YES_OPTION or CANCEL_OPTION
+
+for OK_CANCEL_OPTION or any other: OK_OPTION or CANCEL_OPTION
+
+Note that you should implement a response for CLOSED_OPTION for
+showConfirmDialog. For other dialogs, a null return indicates the dialog was
+closed, just as for Java.
+
+Developers are encouraged to create a separate class that handles general calls.
+An example class can be found in the SwingJS distribution as src/javajs/async/AsyncDialog.java.
+Very simple modifications to the Java allows asynchronous operation using AsyncDialog. Here
+is a simple "do you want to close this frame" example, where you can see that what we have
+done is to set the reply into an ActionListener that is defined in the constructor of
+the AsyncDisplay object:
+
+// Original:
+//
+// private void promptQuit() {
+// int sel = JOptionPane.showConfirmDialog(null, PROMPT_EXIT, NAME, JOptionPane.YES_NO_OPTION);
+// switch (sel) {
+// case JOptionPane.YES_OPTION:
+// resultsTab.clean();
+// seqs.dispose();
+// if (fromMain) {
+// System.exit(0);
+// }
+// break;
+// }
+// }
+
+ private void promptQuitAsync() {
+ new AsyncDialog(new ActionListener() {
+
+ @Override
+ public void actionPerformed(ActionEvent e) {
+ int sel = ((AsyncDialog)e.getSource()).getOption();
+ switch (sel) {
+ case JOptionPane.YES_OPTION:
+ resultsTab.clean();
+ seqs.dispose();
+ if (fromMain) {
+ System.exit(0);
+ }
+ break;
+ }
+ }}).showConfirmDialog(null, PROMPT_EXIT, NAME, JOptionPane.YES_NO_OPTION);
+ }
+
+Very simple!
+
+
+native methods
+--------------
+
+The J2S compiler ignores all static native method declarations.
+Anything of this nature needs to be implemented in JavaScript if it is needed,
+using j2sNative blocks:
+
+/**
+ * @j2sNative
+ *
+ * var putYourJavaScriptCodeHere
+ *
+ */
+
+ Note that if you follow that directly with a {...} block, then
+ the javadoc code will run in JavaScript, and the {...} code will run in Java.
+
+
+key Focus
+---------
+
+As of June, 2019, the keyboard focus manager is fully implemented.
+The one catch is that JTextPane and JTextArea, which already consume
+VK_TAB in Java, cannot use CTRL-TAB to continue a tabbing cycle around
+the components in a window. Instead, CTRL-TAB is absorbed by the browser.
+
+
+LookAndFeel and UI Classes
+--------------------------
+
+SwingJS implements the native browser look and feel as swingjs.plaf.HTML5LookAndFeel.
+There are small differences between all look and feels -- MacOS, Windows, SwingJS.
+
+Expert developers know how to coerce changes in the UI by subclassing the UI for a
+component. This probably will not work in SwingJS.
+
+Note that LookAndFeel in Java usually determines canvas size in a Frame because
+different operating systems (Mac OS vs Windows vs HTML5) will have
+different edge sizes on their frames. If you want to ensure a component size,
+use getContentPane().setPreferredSize().
+
+
+System.exit(0) does not stop all processes
+------------------------------------------
+
+Although System.ext(int) has been implemented in JavaScript, it just closes the
+frames, stops all pending javax.swing.Timer objects in the queue, and runs any
+threads added using Runtime.getRuntime().addShutdownHook(Thread).
+It may not stop all "threads." So don't rely on that.
+Applications are responsible for shutting down prior to executing System.exit(0).
+
+
+myClass.getField not implemented
+--------------------------------
+
+java.lang.reflect.Field is implemented minimally. It is not
+certain that Field.getDeclaringClass() will work. If you just want a
+value of a field, you can do this:
+
+/**
+ *@j2sNative
+ *
+ * return myClass[name]
+ */
+
+But that is not a java.lang.reflection.Field object.
+
+
+"window" and other reserved JavaScript names
+--------------------------------------------
+
+No reserved top-level JavaScript name is allowed for a package name. So, for example,
+one must rename packages such as "window" or "document" to names such as "win" or "doc".
+
+reserved field and method names
+-------------------------------
+
+In order to minimize the chance of added SwingJS field and method names colliding with ones
+developers might use in subclassing Java classes, we have added U+79D8 (first character of Mandarin
+"secret") to the characters already disrecommended by Java documentation ("$" and "_"). The only problem
+would be if you use that character followed by certain English words in certain classes. For example
+\u79D8canvas for JComponents (in java.awt.JSComponent) and \u79D8byte (in java.io.File).
+
+qualified field and method names
+--------------------------------
+
+Method names in SwingJS are fully qualified, meaning two methods with the same Java name but different
+parameters, such as write(int) and write(double), must not have the same name in JavaScript. (In this
+case, we will have write$I and write$D.) However, in certain cases it may be desirable to leave the
+method names unqualified. In particular, when an interface actually represents a JavaScript object,
+the transpiler can leave a method name unqualified. The default situation for this is a class name
+includes ".api.js" (case-sensitive). This means that any method in any class in a package js within
+a package api, or any private interface js that has an outer interface api, will have all-unqualified
+methods. An example of this is swingjs.plaf.JSComboPopupList, which needs to communicate with a jQuery
+object directly using the following interface:
+
+ private interface api {
+
+ interface js extends JQueryObject {
+
+ abstract js j2sCB(Object options);
+
+ abstract Object[] j2sCB(String method);
+
+ abstract Object[] j2sCB(String method, Object o);
+
+ abstract Object[] j2sCB(String method, int i);
+
+ abstract int j2sCB(String OPTION, String name);
+
+ }
+ }
+
+Notice that all these variants of j2sCB() will call the same method in JavaScript by design.
+
+
+missing Math methods
+--------------------
+
+java.lang.Math is worked out, but some methods are missing, either because they
+involve long integer value that are inaccessible in JavaScript, or because I just
+didn't implement them. This is a result of continued Java development.
+It is easy enough to add these methods if you have the source. They go into j2sClazz.js,
+which is combined with other initial libraries into swingjs2.js by build_site.xml
+
+
+Component.getGraphics(), Graphics.dispose()
+-------------------------------------------
+
+Use of component.getGraphics() is discouraged in Java and in SwingJS.
+Specifically in SwingJS, any call to component.getGraphics() or
+BufferedImage.createGraphics() or Graphics.create(...) should be matched with graphics.dispose(),
+particularly when it is called outside the context of a paint(Graphics)
+call from the system.
+
+If you see your graphics scrolling down the page with each repaint,
+look for where you have used Component.getGraphics() and not Graphics.dispose().
+For example, this will definitely NOT work in SwingJS:
+
+ this.paint(getGraphics())
+
+and really should not work in Java, either, as it is technically a resource memory leak.
+
+Instead, if you really do not want to use repaint(), use this:
+
+ Graphics g = getGraphics();
+ paint(g);
+ g.dispose();
+
+
+
+Graphics.setClip()
+------------------
+
+The HTML5 canvas.clip() method is permanent. You can only reset the clip using
+save/restore. This is different from Java, where you can temporarily change it using
+
+ Shape oldClip = Graphics.getClip();
+ Graphics.setClip(newClip);
+ ...
+ Graphics.setClip(oldClip);
+
+If you need to do something like this, you must schedule the paints
+to not have overlapping clip needs.
+
+
+MAJOR ISSUES--for Bob and Udo within SwingJS
+============================================
+
+fonts
+-----
+
+Fonts and FontMetrics will all be handled in JavaScript. Font matching will
+not be exact, and composite (drawn) fonts will not be supported.
+
+SwingJS handles calls such as font.getFontMetrics(g).stringWidth("xxx") by
+creating a <div> containing that text, placing it in an obscure location on
+the page, and reading div.getBoundingClientRect(). This is a VERY precise
+value, but can be a pixel or two off from what Java reports for the same font.
+
+
+OS-dependent classes
+--------------------
+
+Static classes such as:
+
+ java.awt.Toolkit
+ java.awt.GraphicsEnvironment
+
+
+which are created using Class.forName are implemented using classes in the swingjs package.
+
+AWTAccessor is not implemented.
+
+
+AWT component peers and component "ui" user interfaces
+------------------------------------------------------
+
+ComponentPeer is a class that represents a native AWT component.
+Components with such peers are called "heavy-weight" components.
+They are expected to do the dirty work of graphics drawing.
+
+Java Swing implements peers only for JApplet, JDialog, JFrame, and JWindow.
+References to such objects have been removed, but clearly there must be
+some connection to similar DOM objects, even for "light-weight" components.
+
+
+
+MAJOR ISSUES--to be resolved by implementers
+============================================
+
+fonts
+-----
+
+Glyph/composite/outline fonts are not supported.
+
+
+
+threads
+-------
+
+Thread locking and synchronization are not relevant to JavaScript.
+Thus, anything requiring "notify.." or "waitFor.." could be a serious issue.
+
+All threading must be "faked" in JavaScript. Specifically not available is:
+
+ Thread.sleep()
+
+javax.swing.AbstractButton#doClick(pressTime) will not work, as it requires Thread.sleep();
+
+However, java.lang.Thread itself is implemented and used extensively.
+
+Methods thread.start() and thread.run() both work fine.
+
+For simple applications that use Thread.sleep() just to have a delay, as in a frame rate, for
+example, one can use javax.swing.Timer instead. That is fully implemented.
+
+Likewise, java.util.Timer can be replaced with no loss of performance with javax.Swing.Timer.
+Note that java.util.TimerTask is implemented, but it can also be replaced by an implementation of Runnable.
+
+task = new TimerTask(){....};
+t = new java.util.Timer();
+t.schedule(task, 0, 1);
+
+becomes
+
+task = new TimerTask(){....}; // or task = new Runnable() {...}
+t = new javax.swing.Timer(1, new ActionListener() {
+ @Override
+ public void actionPerformed(ActionEvent e) {
+ task.run();
+ }
+};
+t.setInitialDelay(0); // not particularly necessary
+t.start();
+
+In addition, SwingJS provides swingjs.JSThread, which can be subclassed
+if desired. This class allows simple
+
+ while(!interrupted()){
+ wait()
+ ...
+ }
+
+action through an asynchronous function run1(mode). For example:
+
+ protected void run1(int mode) {
+ try {
+ while (true)
+ switch (mode) {
+ case INIT:
+ // once-through stuff here
+ mode = LOOP;
+ break;
+ case LOOP:
+ if (!doDispatch || isInterrupted()) {
+ mode = DONE;
+ } else {
+ Runnable r = new Runnable() {
+ public void run() {
+ // put the loop code here
+ }
+ };
+ dispatchAndReturn(r);
+ if (isJS)
+ return;
+ }
+ break;
+ // add more cases as needed
+ case DONE:
+ // finish up here
+ if (isInterrupted())
+ return;
+ // or here
+ break;
+ }
+ } finally {
+ // stuff here to be executed after each loop in JS or at the end in Java
+ }
+ }
+
+image loading
+-------------
+- All image loading in SwingJS is synchronous. A MediaTracker call will immediately return "complete".
+ However, it still may take one system clock tick to fully load images. Thus, it is recommended that
+ images be preloaded in the static block of the applet if it is necessary that they be available in init().
+ This is only an issue if you are trying to access the pixel buffer of the image in JavaScript.
+
+- Applet.getImage(path, name) will return null if the image does not exist.
+
+- BufferedImage: only "support" imageType RGB and ARGB
+
+ -BH: This is a temporary edit, just to get us started. Certainly GRAY will be needed
+
+
+BigInteger and BigDecimal
+-------------------------
+
+java.math.BigInteger is fully supported; java.math.BigDecimal is roughed
+in and not fully tested (07/2019).
+
+Both classes present significant issues for JavaScript, as they are based in
+Java's 64-bit long for all their operations. Here is the JavaDoc note I added
+to BigInteger:
+
+ * SwingJS note: Because of the limitations of JavaScript with regard
+ * to long-integer bit storage as a double, this implementation drops
+ * the integer storage bit length to 24, giving 48 for long and leaving
+ * the last 16 bits clear for the exponent of the double number. This should
+ * not affect performance significantly. It does increase the storage
+ * size by about 33%. By bringing an "int" to 3 bytes, we can easily construct
+ * and use byte[] data intended for the original BitSet.
+
+"Easily" may be a bit strong there. This was a serious challenge.
+
+BigDecimal seems to run normally, but in order to do that, my hack involves
+reducing the size of an integer that is allowed to be stored as such and not
+in byte[] as a BigInteger. I'm sure there is a performance hit, but it does work.
+
+no format internationalization
+------------------------------
+
+For now, just en for number and date formatters
+
+no winding rules
+----------------
+
+ When filling a graphic, only nonzero winding rule is implemented in HTML5 Canvas2D.
+
+
+
+text-related field implementation
+---------------------------------
+
+Text fields are:
+
+JTextField (JavaScript <input type="text">)
+JTextArea (JavaScript <textarea>)
+JTextPane (JavaScript <div>)
+JEditorPane (JavaScript <div>)
+
+For the initial implementation, we don't implement infinite undo/redo, and the abstract
+document model is much less elaborate. Only PlainDocument (in the form of JSPlainDocument)
+is implemented. The Document returned by JTextField.getDocument() is a javax.swing.text.Document.
+
+All scrolling is handled by HTML5. javax.swing.AutoScroller is not implemented.
+public static methods .stop, .isRunning, .processMouseDragged require true Java threading
+and so are not implmented. javax.swing.text.View and its subclasses are not implemented.
+
+The JS document model does not allow two text fields to address the same underlying document.
+
+JavaScript is slightly different from Java in that the field value is changed asynchronously after
+the keypressed event, so Java actions that are keyed to KEY_PRESSED may not pick up the new
+key value even after SwingUtilities.invokeLater() is called. Thus, key pressed actions may need
+to be recorded after a key released event instead.
+
+Formatter/Regex limitations
+---------------------------
+
+Some browsers cannot process Regex "look-behind" process such as (?<=\W)
+java.util.regex.Matcher and Pattern use JavaScript's RegExp object rather than
+the native Java object. These are not identical. Only flags /igm are supported.
+Matcher.start(groupID) is not supported.
+
+java.util.Formatter will function correctly for all standard %... patterns.
+
+integer 1/0 == Infinity
+-----------------------
+
+1/0 in Java throws "java.lang.ArithmeticException: / by zero", but in JavaScript is just Infinity.
+
+
+
+Summary
+-------
+
+These are all the known limitations of SwingJS. We have not found any of these limitations
+to be show-stoppers. The primary issue for newcomers to SwingJS is having the source code.
+You must check that source code for all your library jar files is available or, if you
+choose, you will need to decompile those classes. We have used decompilation on some projects,
+and it works just fine. So, technically, all we really need are JAR/class files. But the
+source is by far superior. It's generally prettier, and it has the license information that
+may or may not be present with the JAR or class files. Use class files at your own risk.
+
+Bob Hanson
+2019.08.16
+
+
+Additional Issues
+-----------------
+
+Annotation is working for classes, methods, and fields (12/22/19). Method reflection, however,
+is limited. Interfaces do not expose their methods, as the transpiler does not actually transpile
+the interfaces themselves. And method reflection only includes annotated methods.
+
+java.util.concurrent is not fully elaborated. This package is rewritten to not actually use the
+memory handling capabilities of concurrency, which JavaScript does not have access to.
+
+System.getProperties() just returns a minimal set of properties.
+
+
--- /dev/null
+20201222130550
--- /dev/null
+This is sources/net.sf.j2s.java.core/dist/DEV_NOTES.txt
+
+_j2sclasslist.txt
+
+the list of .js files concatenated into coreswingjs.js and minified to coreswingjs.z.js
+
+
+SwingJS-site.zip
+
+the full site directory for SwingJS including all files not in the test/ directory.
--- /dev/null
+java/applet/Applet.js
+java/applet/AppletContext.js
+java/applet/AppletStub.js
+java/applet/JSApplet.js
+java/awt/ActiveEvent.js
+java/awt/Adjustable.js
+java/awt/AWTEvent.js
+java/awt/AWTEventMulticaster.js
+java/awt/AWTKeyStroke.js
+java/awt/BasicStroke.js
+java/awt/BorderLayout.js
+java/awt/Button.js
+java/awt/Color.js
+java/awt/color/ColorSpace.js
+java/awt/Component.js
+java/awt/ComponentOrientation.js
+java/awt/ContainerOrderFocusTraversalPolicy.js
+java/awt/Container.js
+java/awt/Cursor.js
+java/awt/DefaultFocusTraversalPolicy.js
+java/awt/DefaultKeyboardFocusManager.js
+java/awt/Dialog.js
+java/awt/Dimension.js
+java/awt/dnd/peer/DropTargetPeer.js
+java/awt/event/ActionListener.js
+java/awt/event/AdjustmentEvent.js
+java/awt/event/AdjustmentListener.js
+java/awt/event/AWTEventListener.js
+java/awt/event/ComponentAdapter.js
+java/awt/event/ComponentEvent.js
+java/awt/event/ComponentListener.js
+java/awt/event/ContainerListener.js
+java/awt/event/FocusEvent.js
+java/awt/event/FocusListener.js
+java/awt/event/HierarchyBoundsListener.js
+java/awt/event/HierarchyListener.js
+java/awt/event/InputEvent.js
+java/awt/event/InputMethodListener.js
+java/awt/event/InvocationEvent.js
+java/awt/event/ItemEvent.js
+java/awt/event/ItemListener.js
+java/awt/event/KeyListener.js
+java/awt/event/MouseEvent.js
+java/awt/event/MouseListener.js
+java/awt/event/MouseMotionListener.js
+java/awt/event/MouseWheelListener.js
+java/awt/event/TextListener.js
+java/awt/event/WindowAdapter.js
+java/awt/event/WindowEvent.js
+java/awt/event/WindowFocusListener.js
+java/awt/event/WindowListener.js
+java/awt/event/WindowStateListener.js
+java/awt/EventDispatchThread.js
+java/awt/EventFilter.js
+java/awt/EventQueue.js
+java/awt/EventQueueItem.js
+java/awt/FlowLayout.js
+java/awt/FocusTraversalPolicy.js
+java/awt/Font.js
+java/awt/font/FontRenderContext.js
+java/awt/FontMetrics.js
+java/awt/Frame.js
+java/awt/geom/AffineTransform.js
+java/awt/geom/Dimension2D.js
+java/awt/geom/Path2D.js
+java/awt/geom/PathIterator.js
+java/awt/geom/Point2D.js
+java/awt/geom/Rectangle2D.js
+java/awt/geom/RectangularShape.js
+java/awt/geom/RectIterator.js
+java/awt/GraphicsCallback.js
+java/awt/GraphicsConfiguration.js
+java/awt/GraphicsDevice.js
+java/awt/GraphicsEnvironment.js
+java/awt/Image.js
+java/awt/image/ImageObserver.js
+java/awt/Insets.js
+java/awt/ItemSelectable.js
+java/awt/JSComponent.js
+java/awt/JSDialog.js
+java/awt/JSFrame.js
+java/awt/JSPanel.js
+java/awt/KeyboardFocusManager.js
+java/awt/KeyEventDispatcher.js
+java/awt/KeyEventPostProcessor.js
+java/awt/Label.js
+java/awt/LayoutManager.js
+java/awt/LayoutManager2.js
+java/awt/LightweightDispatcher.js
+java/awt/Paint.js
+java/awt/Panel.js
+java/awt/peer/ComponentPeer.js
+java/awt/peer/ContainerPeer.js
+java/awt/peer/FramePeer.js
+java/awt/peer/KeyboardFocusManagerPeer.js
+java/awt/peer/LightweightPeer.js
+java/awt/peer/WindowPeer.js
+java/awt/Point.js
+java/awt/Queue.js
+java/awt/Rectangle.js
+java/awt/RenderingHints.js
+java/awt/Scrollbar.js
+java/awt/ScrollPane.js
+java/awt/Shape.js
+java/awt/Stroke.js
+java/awt/TextArea.js
+java/awt/TextComponent.js
+java/awt/TextField.js
+java/awt/Toolkit.js
+java/awt/Transparency.js
+java/awt/Window.js
+java/beans/ChangeListenerMap.js
+java/beans/PropertyChangeEvent.js
+java/beans/PropertyChangeListener.js
+java/beans/PropertyChangeSupport.js
+java/lang/AbstractStringBuilder.js
+java/lang/Class.js
+java/lang/Enum.js
+java/lang/Iterable.js
+java/lang/reflect/Constructor.js
+java/lang/reflect/Method.js
+java/lang/StringBuffer.js
+java/lang/StringBuilder.js
+java/lang/Thread.js
+java/lang/ThreadGroup.js
+java/math/RoundingMode.js
+java/net/URL.js
+java/net/URLStreamHandlerFactory.js
+java/net/HttpURLConnection.js
+java/net/URLStreamHandler.js
+javax/net/ssl/HttpsUrlConnection.js
+java/text/CharacterIterator.js
+java/text/DecimalFormat.js
+java/text/DecimalFormatSymbols.js
+java/text/DigitList.js
+java/text/FieldPosition.js
+java/text/Format.js
+java/text/NumberFormat.js
+java/util/AbstractCollection.js
+java/util/AbstractList.js
+java/util/AbstractMap.js
+java/util/AbstractSequentialList.js
+java/util/AbstractSet.js
+java/util/ArrayList.js
+java/util/Arrays.js
+java/util/Collection.js
+java/util/Collections.js
+java/util/Comparator.js
+java/util/Deque.js
+java/util/Dictionary.js
+java/util/Enumeration.js
+java/util/EventListener.js
+java/util/EventObject.js
+java/util/HashMap.js
+java/util/HashSet.js
+java/util/Hashtable.js
+java/util/IdentityHashMap.js
+java/util/Iterator.js
+java/util/LinkedHashMap.js
+java/util/LinkedList.js
+java/util/List.js
+java/util/ListResourceBundle.js
+java/util/Locale.js
+java/util/Map.js
+java/util/Objects.js
+java/util/Queue.js
+java/util/Random.js
+java/util/RandomAccess.js
+java/util/ResourceBundle.js
+java/util/Set.js
+java/util/TimSort.js
+java/util/Vector.js
+javajs/api/JSFunction.js
+javajs/util/AjaxURLConnection.js
+javajs/util/AjaxURLStreamHandlerFactory.js
+javajs/util/AU.js
+javajs/util/JSThread.js
+javajs/util/Lst.js
+javajs/util/PT.js
+javajs/util/Rdr.js
+javajs/util/SB.js
+javax/swing/AbstractAction.js
+javax/swing/AbstractButton.js
+javax/swing/AbstractListModel.js
+javax/swing/Action.js
+javax/swing/ActionMap.js
+javax/swing/AncestorNotifier.js
+javax/swing/ArrayTable.js
+javax/swing/border/AbstractBorder.js
+javax/swing/border/BevelBorder.js
+javax/swing/border/Border.js
+javax/swing/border/CompoundBorder.js
+javax/swing/border/EmptyBorder.js
+javax/swing/border/EtchedBorder.js
+javax/swing/border/LineBorder.js
+javax/swing/border/TitledBorder.js
+javax/swing/BorderFactory.js
+javax/swing/BoundedRangeModel.js
+javax/swing/BoxLayout.js
+javax/swing/ButtonGroup.js
+javax/swing/ButtonModel.js
+javax/swing/ClientPropertyKey.js
+javax/swing/ComboBoxModel.js
+javax/swing/DefaultBoundedRangeModel.js
+javax/swing/DefaultButtonModel.js
+javax/swing/DefaultComboBoxModel.js
+javax/swing/DefaultSingleSelectionModel.js
+javax/swing/DropMode.js
+javax/swing/event/AncestorEvent.js
+javax/swing/event/AncestorListener.js
+javax/swing/event/CaretEvent.js
+javax/swing/event/CaretListener.js
+javax/swing/event/ChangeEvent.js
+javax/swing/event/ChangeListener.js
+javax/swing/event/DocumentEvent.js
+javax/swing/event/DocumentListener.js
+javax/swing/event/EventListenerList.js
+javax/swing/event/ListDataEvent.js
+javax/swing/event/ListDataListener.js
+javax/swing/event/UndoableEditEvent.js
+javax/swing/event/UndoableEditListener.js
+javax/swing/FocusManager.js
+javax/swing/InternalFrameFocusTraversalPolicy.js
+javax/swing/LayoutComparator.js
+javax/swing/LayoutFocusTraversalPolicy.js
+javax/swing/SortingFocusTraversalPolicy.js
+javax/swing/SwingContainerOrderFocusTraversalPolicy.js
+javax/swing/SwingDefaultFocusTraversalPolicy.js
+javax/swing/Icon.js
+javax/swing/ImageIcon.js
+javax/swing/InputMap.js
+javax/swing/JApplet.js
+javax/swing/JButton.js
+javax/swing/JCheckBox.js
+javax/swing/JCheckBoxMenuItem.js
+javax/swing/JComboBox.js
+javax/swing/JComponent.js
+javax/swing/JFrame.js
+javax/swing/JLabel.js
+javax/swing/JLayeredPane.js
+javax/swing/JMenu.js
+javax/swing/JMenuBar.js
+javax/swing/JMenuItem.js
+javax/swing/JPanel.js
+javax/swing/JPopupMenu.js
+javax/swing/JRadioButtonMenuItem.js
+javax/swing/JRootPane.js
+javax/swing/JScrollBar.js
+javax/swing/JScrollPane.js
+javax/swing/JSeparator.js
+javax/swing/JTextArea.js
+javax/swing/JTextField.js
+javax/swing/JToggleButton.js
+javax/swing/JViewport.js
+javax/swing/KeyboardManager.js
+javax/swing/KeyStroke.js
+javax/swing/ListModel.js
+javax/swing/LookAndFeel.js
+javax/swing/MenuElement.js
+javax/swing/MutableComboBoxModel.js
+javax/swing/plaf/ActionMapUIResource.js
+javax/swing/plaf/basic/BasicBorders.js
+javax/swing/plaf/BorderUIResource.js
+javax/swing/plaf/ColorUIResource.js
+javax/swing/plaf/ComponentUI.js
+javax/swing/plaf/DimensionUIResource.js
+javax/swing/plaf/FontUIResource.js
+javax/swing/plaf/InputMapUIResource.js
+javax/swing/plaf/InsetsUIResource.js
+javax/swing/plaf/UIResource.js
+javax/swing/RepaintManager.js
+javax/swing/RootPaneContainer.js
+javax/swing/Scrollable.js
+javax/swing/ScrollPaneConstants.js
+javax/swing/ScrollPaneLayout.js
+javax/swing/SingleSelectionModel.js
+javax/swing/SizeRequirements.js
+javax/swing/SwingConstants.js
+javax/swing/SwingPaintEventDispatcher.js
+javax/swing/SwingUtilities.js
+javax/swing/text/AbstractDocument.js
+javax/swing/text/AttributeSet.js
+javax/swing/text/Caret.js
+javax/swing/text/DefaultCaret.js
+javax/swing/text/DefaultEditorKit.js
+javax/swing/text/Document.js
+javax/swing/text/EditorKit.js
+javax/swing/text/Element.js
+javax/swing/text/GapContent.js
+javax/swing/text/GapVector.js
+javax/swing/text/JTextComponent.js
+javax/swing/text/MutableAttributeSet.js
+javax/swing/text/PlainDocument.js
+javax/swing/text/PlainView.js
+javax/swing/text/Position.js
+javax/swing/text/Segment.js
+javax/swing/text/SegmentCache.js
+javax/swing/text/SimpleAttributeSet.js
+javax/swing/text/Style.js
+javax/swing/text/StyleConstants.js
+javax/swing/text/StyleContext.js
+javax/swing/text/TabExpander.js
+javax/swing/text/TextAction.js
+javax/swing/text/Utilities.js
+javax/swing/text/View.js
+javax/swing/tree/TreeNode.js
+javax/swing/UIDefaults.js
+javax/swing/UIManager.js
+javax/swing/undo/AbstractUndoableEdit.js
+javax/swing/undo/CompoundEdit.js
+javax/swing/undo/UndoableEdit.js
+javax/swing/ViewportLayout.js
+javax/swing/WindowConstants.js
+sun/awt/AppContext.js
+sun/awt/AWTAutoShutdown.js
+sun/awt/CausedFocusEvent.js
+sun/awt/ComponentFactory.js
+sun/awt/KeyboardFocusManagerPeerProvider.js
+sun/awt/MostRecentKeyValue.js
+sun/awt/MostRecentThreadAppContext.js
+sun/awt/PaintEventDispatcher.js
+sun/awt/PostEventQueue.js
+sun/awt/RequestFocusController.js
+sun/awt/SunToolkit.js
+sun/awt/WindowClosingListener.js
+sun/awt/WindowClosingSupport.js
+sun/awt/image/DataStealer.js
+sun/awt/image/IntegerComponentRaster.js
+sun/awt/image/IntegerInterleavedRaster.js
+sun/awt/image/SunWritableRaster.js
+sun/font/FontDesignMetrics.js
+sun/swing/DefaultLookup.js
+sun/swing/SwingLazyValue.js
+sun/text/resources/FormatData.js
+sun/text/resources/en/FormatData_en.js
+sun/util/resources/LocaleData.js
+sun/util/locale/BaseLocale.js
+sun/util/locale/LocaleUtils.js
+sun/util/locale/provider/LocaleProviderAdapter.js
+sun/util/locale/provider/LocaleDataMetaInfo.js
+swingjs/a2s/A2SContainer.js
+swingjs/a2s/A2SEvent.js
+swingjs/a2s/A2SListener.js
+swingjs/a2s/Applet.js
+swingjs/a2s/Button.js
+swingjs/a2s/Label.js
+swingjs/a2s/Panel.js
+swingjs/a2s/Scrollbar.js
+swingjs/a2s/ScrollPane.js
+swingjs/a2s/TextArea.js
+swingjs/a2s/TextField.js
+swingjs/api/Interface.js
+swingjs/api/js/DOMNode.js
+swingjs/api/js/HTML5CanvasContext2D.js
+swingjs/api/js/JSInterface.js
+swingjs/jquery/JQueryUI.js
+swingjs/JSApp.js
+swingjs/JSAppletThread.js
+swingjs/JSAppletViewer.js
+swingjs/JSFocusPeer.js
+swingjs/JSFontMetrics.js
+swingjs/JSFrameViewer.js
+swingjs/JSGraphics2D.js
+swingjs/JSGraphicsConfiguration.js
+swingjs/JSGraphicsEnvironment.js
+swingjs/JSImage.js
+swingjs/JSImagekit.js
+swingjs/JSMouse.js
+swingjs/JSNullComponentPeer.js
+swingjs/JSScreenDevice.js
+swingjs/JSThreadGroup.js
+swingjs/JSToolkit.js
+swingjs/JSUtil.js
+swingjs/plaf/ButtonListener.js
+swingjs/plaf/DefaultMenuLayout.js
+swingjs/plaf/HTML5LookAndFeel.js
+swingjs/plaf/JSAppletUI.js
+swingjs/plaf/JSButtonUI.js
+swingjs/plaf/JSCheckBoxMenuItemUI.js
+swingjs/plaf/JSCheckBoxUI.js
+swingjs/plaf/JSComboBoxUI.js
+swingjs/plaf/JSComponentUI.js
+swingjs/plaf/JSEventHandler.js
+swingjs/plaf/JSFrameUI.js
+swingjs/plaf/JSGraphicsUtils.js
+swingjs/plaf/JSLabelUI.js
+swingjs/plaf/JSLayeredPaneUI.js
+swingjs/plaf/JSLightweightUI.js
+swingjs/plaf/JSMenuBarUI.js
+swingjs/plaf/JSMenuItemUI.js
+swingjs/plaf/JSMenuUI.js
+swingjs/plaf/JSPanelUI.js
+swingjs/plaf/JSPopupMenuSeparatorUI.js
+swingjs/plaf/JSPopupMenuUI.js
+swingjs/plaf/JSRadioButtonMenuItemUI.js
+swingjs/plaf/JSRadioButtonUI.js
+swingjs/plaf/JSRootPaneUI.js
+swingjs/plaf/JSScrollBarUI.js
+swingjs/plaf/JSScrollPaneUI.js
+swingjs/plaf/JSSeparatorUI.js
+swingjs/plaf/JSSliderUI.js
+swingjs/plaf/JSTextAreaUI.js
+swingjs/plaf/JSTextFieldUI.js
+swingjs/plaf/JSTextUI.js
+swingjs/plaf/JSTextViewUI.js
+swingjs/plaf/JSViewportUI.js
+swingjs/plaf/JSWindowUI.js
+swingjs/plaf/LazyActionMap.js
+swingjs/plaf/Resizer.js
+swingjs/plaf/TextListener.js
+
+
--- /dev/null
+Notes
+=====
+
+---IMPORTANT CHARACTER SET NOTE---
+
+It is critical that all development work in Java2Script
+be done in UTF-8. This means:
+
+- making sure your Eclipse project is set up for UTF-8 (not the Eclipse default?)
+- making sure your server can serve up UTF-8 by default for any browser-loaded files
+- making sure you don't edit a Java2Script class file or one of the site .js files
+ using a non-UTF-8 editor. It may replace non-Latin characters with "?" or garbage.
+- making sure that your web pages are delivered with proper headings indicating HTML5 and UTF-8
+
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="utf-8">
+
+Note that the DOCTYPE tag is critical for some browsers to switch into HTML5 mode. (MSIE?)
+
+
+
+
+In particular, the Mandarin character 秘 (mi; "secret") is used extensively throughout
+the SwingJS class files to distinguish j2s-specific fields and methods that must not
+ever be shadowed or overridden by subclasses. For example, we see in java.lang.Thread.java:
+
+ public static JSThread 秘thisThread;
+
+----------------------------------
+
+
+updated 12/6/2020 -- note about restrictions on long, including BitSet and Scanner
+updated 3/21/2020 -- adds note about HashMap, Hashtable, and HashSet iterator ordering
+updated 3/20/2020 -- adds note about interning, new String("xxx"), and "xxx"
+updated 2/26/2020 -- adds Graphics.setClip issue
+updated 12/22/19 -- additional issues
+updated 11/03/19 -- adds information about File.exists() and points to src/javajs/async
+updated 10/26/19 -- adds information about File.createTempFile()
+updated 8/16/19 -- minor typos and added summary paragraph
+updated 7/19/19 -- clarification that AWT and Swing classes are supported directly
+updated 5/13/19 -- Mandarin U+79D8 reserved character; Missing Math methods; int and long
+updated 5/10/19 -- adds a section on static issues in multi-(duplicate)-applet pages
+updated 1/4/19 -- nio
+updated 9/15/18 -- adds integer 1/0 == Infinity
+updated 7/24/18 -- most classes replaced with https://github.com/frohoff/jdk8u-jdk
+updated 6/5/17 -- reserved package name "window"
+updated 3/11/17 -- myClass.getField
+updated 3/7/17 -- overloading of JSplitPane.setDividerLocation
+updated 3/2/17 -- more indication of classes not implemented (KeyListener)
+
+=============================================================================
+SwingJS and OpenJDK 8+
+=============================================================================
+
+SwingJS implements a wide range of the Java language in JavaScript. The base
+version for this implementation is OpenJDK8. some classes are implemented using
+older source code, and there are some missing methods. For the most part, this is
+no real problem. You can add or modify any java class just be adding it as source
+in your project. Or (preferably) you can contact me, and I can get it into the
+distribution. Or (even more preferably) you can do that via a patch submission.
+
+=================
+DESIGN PHILOSOPHY
+=================
+
+The java2script/SwingJS design goal is to recreate a recognizable, easily debuggable
+equivalent in JavaScript for as much of Java as practical. This means, for example,
+that one can call in JavaScript
+
+ new java.util.Hashtable()
+
+and for all practical purposes it will appear that Java is running.
+
+
+Method and Field Disambiguation
+-------------------------------
+
+SwingJS has no problem with the overloading of methods, for example:
+
+ public void print(int b);
+ public void print(float b);
+
+JavaScript does not allow overloading of methods, and the common practice in
+Java of naming a field the same as a method -- isAllowed and isAllowed() -- is
+not possible in JavaScript. As a result, SwingJS implements "fully-qualified"
+method names using "$" parameter type separation. Thus, these methods in SwingJS
+will be referred to as print$I and print$F. The rules for this encoding are
+relatively simple:
+
+1. The seven primitive types in Java are encoded $I (int), $L (long), $F (float),
+$D (double), $B (byte) $Z (boolean), and $H (short).
+
+2. String and Object are encoded as $S and $O, respectively.
+
+3. "java_lang_" is dropped for all other classes in the java.lang package (as in Java).
+ For example: $StringBuffer, not $java_lang_StringBuffer
+
+4. All other classes are encoded as
+
+ "$" + Class.getName().replace(".","_")
+
+For example, in Java we see:
+
+ public void equals(Object o) {...}
+
+Whereas in SwingJS we have:
+
+ Clazz.newMeth(C$, 'equals$O', function (o) {...}
+
+And
+
+ this.getContentPane().add(bar, "North");
+
+becomes
+
+ this.getContentPane$().add$java_awt_Component$O(bar, "North");
+
+5. Arrays are indicated with appended "A" for each level. So
+
+ setDataVector(Object[][] dataVector, Object[] columnIdentifiers)
+
+becomes
+
+ setDataVector$OAA$OA(dataVector, columnIdentifiers)
+
+(It is recognized that this design does introduce a bit of ambiguity, in that
+ in principal there could be user class named XA and X in the same package,
+ and methods a(X[]) and a(XA) in the same class that cannot be distinguished.
+ The benefit of this simple system, however, triumphed over the unlikelyhood
+ of that scenario.) The transpiler could be set to flag this possibility.
+
+6. Constructors are prepended with "c$". So
+
+ public JLabel(String text) {...}
+
+becomes:
+
+ Clazz.newMeth(C$, 'c$$S', function (text) {...});
+
+Field disambiguation involves prepending. In Java, a class and its subclass
+can both have the same field name, such as
+
+ boolean visible;
+
+When this happens, it is called "shadowing", and though not recommended, Java allows
+it. The Java2Script transpiler will prepend such shadowing fields with "$" so that the
+subclass instance has both "visible" (for use in its methods inherited from its
+superclass) and "$visible" (for its own methods). Thus, we might see in Java:
+
+ this.visible = super.visible;
+
+while in SwingJS we will see:
+
+ this.$visible=this.visible;
+
+since JavaScript does not have the "super" keyword.
+
+
+
+Parameterless methods such as toString() are appended with "$" to become toString$().
+The one exception to this rule is private methods, which are saved in (truly) private
+array in the class (and are not accessible by reflection). Private parameterless
+methods retain their simple Java name, since they cannot conflict with field names.
+
+This renaming of methods has a few consequences, which are discussed more fully below.
+See particularly the section on "qualified field and method names", where it is described
+how you can use packages or classes or interfaces with ".api.js" in them to represent JavaScript
+objects for which all method names are to be left unqualified. Note that it is not
+possible to cherry-pick methods to be unqualified; only full packages, classes or
+interfaces can hold this status.
+
+The swingjs.api.js package in particular contains a number of useful interfaces that
+you can import into your project for JavaScript-specific capabilities.
+
+
+Applet vs. Application
+----------------------
+
+One of the very cool aspects of SwingJS is that it doesn't particularly matter if a browser-based
+Java app is an "applet" or an "application". We don't need JNLP (Java Network Launch Protocol)
+because now we can just start up any Java application in a browser just as easily as any applet.
+The associative array that passes information to the SwingJS applet (information that formerly
+might have been part of the APPLET tag, such as width, height, and codebase, always referred to
+in our writing as "the Info array") allows the option to specify the JApplet/Applet "code"
+class or the application "main" class. Either one will run just fine.
+
+
+Performance
+-----------
+
+Obviously, there are limitations. One is performance, but we have seen reproducible
+performance at 1/6 - 1/3 the speed of Java. Achieving this performance may require
+some refactoring of the Java to make it more efficient in both Java and JavaScript.
+"for" loops need to be more carefully crafted; use of "new" and "instanceof" need to be
+minimized in critical areas. Note that method overloading -- that is, the same method name
+with different parameters, such as read(int) and read(byte) -- is no longer any problem.
+
+
+Threads
+-------
+
+Although there is only a single thread in JavaScript, meaning Thread.wait(), Thread.sleep(int) and
+Thread.notify() cannot be reproduced, we have found that this is not a serious limitation.
+For example, javax.swing.Timer() works perfectly in JavaScript. All it means is that threads
+that use sleep(int) or notify() must be refactored to allow Timer-like callbacks. That is,
+they must allow full exit and re-entry of Thread.run(), not the typical while/sleep motif.
+
+The key is to create a state-based run() that can be exited and re-entered in JavaScript.
+
+
+Static fields
+-------------
+
+Final static primitive "constant" fields (String, boolean, int, etc.) such as
+
+static final int TEST = 3;
+static final String MY_STRING = "my " + "string";
+
+are converted to their primitive form automatically by the Eclipse Java compiler
+and do not appear in the JavaScript by their names.
+
+Other static fields are properties of their class and can be used as expected.
+
+Note, however, that SwingJS runs all "Java" code on a page in a common "jvm"
+(like older versions of Java). So, like the older Java schema, the JavaScript
+equivalents of both applets and applications will share all of their static
+fields and methods. This includes java.lang.System.
+
+Basically, SwingJS implementations of Java run in a browser page-based sandbox
+instead of an applet-specific one.
+
+In general, this is no problem. But if we are to implement pages with
+multiple applets present, we must be sure to only have static references
+that are "final" or specifically meant to be shared in a JavaScript
+environment only (since they will not be shared in Java).
+
+A simple solution, if static non-constant references are needed, is to attach the
+field to Thread.currentThread.threadGroup(), which is an applet-specific reference.
+Be sure, if you do this, that you use explicit setters and getters:
+
+For example,
+
+private static String myvar;
+
+...
+
+public void setMyVar(String x) {
+ ThreadGroup g = Thread.currentThread().threadGroup();
+ /**
+ * @j2sNative g._myvar = x;
+ *
+ */
+ {
+ myvar = x;
+ }
+}
+
+public String getMyVar() {
+ ThreadGroup g = Thread.currentThread().threadGroup();
+ /**
+ * @j2sNative return g._myvar || null;
+ *
+ */
+ {
+ return myvar;
+ }
+}
+
+ in Java will get and set x the same in JavaScript and in Java.
+
+
+A convenient way to do this in general is to supply a singleton class with
+explicitly private-only constructors and then refer to it in Java and in JavaScript
+instead of using static field, referring to myclass.getIntance().xxx instead of
+myclass.xxx in Java (and JavaScript).
+
+This was done extensively in the Jalview project. See jalview.bin.Instance.
+
+
+Helper Packages -- swingjs/ and javajs/
+---------------------------------------
+
+The SwingJS library is the swingjs/ package. There are interfaces that may be of assistance
+in swingjs/api, but other than that, it is not recommended that developers access classes in
+this package. The "public" nature of their methods is really an internal necessity.
+
+In addition to swingjs/, though, there are several useful classes in the javajs/ package
+that could be very useful. This package is a stand-alone package that can be
+cloned in any Java project that also would be great to have in any JavaScript project
+-- SwingJS-related or not. Functionality ranges from reading and writing various file
+formats, including PDF, BMP, PNG, GIF, JPG, JSON, ZIP, and CompoundDocument formats.
+
+A variety of highly efficient three- and four-dimensional point, vector, matrix, and
+quaternion classes are included, as they were developed for JSmol and inherited from that
+project.
+
+Of particular interest should be javajs/async/, which includes
+
+javajs.async.Async
+javajs.async.AsyncColorChooser
+javajs.async.AsyncDialog
+javajs.async.AsyncFileChooser
+
+See javajs.async.Async JavaDoc comments for a full description of
+these useful classes.
+
+
+Modal Dialogs
+-------------
+
+Although true modal dialogs are not possible with only one thread, a functional equivalent --
+asynchronous modal dialogs -- is relatively easy to set up. All the JOptionPane dialogs will
+return PropertyChangeEvents to signal that they have been disposed of and containing the results.
+See below and classes in the javajs.async package.
+
+
+Native calls
+------------
+
+Native calls in Java are calls to operating system methods that are not in Java. JavaScript
+has no access to these, of course, and they must all be replaced by JavaScript equivalents.
+Fortunately, they are not common, and those that are present in Java (for example, in calculating
+checksums in ZIP file creation) are at a low enough level that most developers do not utilize them
+or do not even have access to them. All native calls in Java classes have been replaced by
+Java equivalents.
+
+
+Swing GUI Peers and UIClasses
+-----------------------------
+
+One of the biggest adaptations introduced in SwingJS is in the area of the graphical
+user interface. The issue here is complex but workable. In Java there are two background
+concepts -- the Component "peer" (one per "heavy-weight" component, such as a Frame) and the
+component "uiClass" (one per component, such as JButton or JTextField).
+
+Peers are native objects of the operating system. These are the virtual buttons and text areas
+that the user is interacting with at a very base level. Their events are being passed on to
+Java or the browser by the operating system. UI classes provide a consistent "look and feel"
+for these native objects, rendering them onto the native window canvas and handling all
+user-generated events. They paint the borders, the backgrounds, the highlights, of every
+control you see in Java. There is one-to-one correspondence of Swing classes and UI classes.
+Setting the Look and Feel for a project amounts to selecting the directory from which to draw
+these UI classes. The UI classes can be found in the javax.swing.plaf ("platform look and feel")
+package.
+
+Early on in the development of SwingJS, we decided not to fully reproduce the painfully detailed
+bit-by-bit painting of controls as is done in Java. Instead, we felt it was wiser to utilize the standard
+HTML5 UI capabilities as much as possible, using DIV, and INPUT especially, with extensive use
+of CSS and sometimes jQuery (menus, and sliders, for example). Thus, we have created a new
+set of UIs -- the "HTML5 Look and Feel". These classes can be found in swingjs.plaf. Besides being
+more adaptable, this approach allows far more versatility to SwingJS developers, allowing them
+to modify the GUI to suit their needs if desired.
+
+In SwingJS, since we have no access to native peers except through the browser DOM,
+it seemed logical to merge the peer and UI idea. So instead of having one peer per heavy-weight control and
+one UI class instance for each control type, we just have one UI class instance per control, and
+that UI class instance is what is being referred to when a "peer" is notified.
+
+In some ways this is a throw back to when all of Swing's components were subclasses of
+specific AWT components such as Button and List. These "heavy-weight components" all had their
+own individual native peers and thus automatically took on the look and feel provided by the OS.
+Later Swing versions implemented full look and feel for all peers, leaving only JDialog, JFrame,
+and a few other classes to have native peers. But in SwingJS we have again a 1:1 map of component
+and UI class/peer instance.
+
+The origin of most issues (read "bugs") in relation to the GUI will probably be found in the
+swingjs.plaf JSxxxxUI.java code.
+
+
+Swing-only Components -- no longer an issue
+-------------------------------------------
+
+Swing was introduced into Java well after the Java Abstract Window Toolkit (AWT) was well
+established. As such, its designers chose to allow AWT controls such as Button and List to be used
+alongside their Swing counterparts JButton and JList. Reading the code, it is clear that this
+design choice posed a huge headache for Swing class developers.
+
+For SwingJS, we decided from the beginning NOT to allow this mixed-mode programming and
+instead to require that all components be Swing components.
+
+However, this is no longer an issue. All AWT components in SwingJS are now subclasses of
+javax.swing.JComponent. So far, we have found no problem with this.
+
+
+The a2s Adapter Package
+-----------------------
+
+Originally, we thought that we would restrict ourselves to JApplets only. That is, only
+Swing-based applets. But as we worked, we discovered that there are a lot of great
+applets out there that are pre-Swing pure-AWT java.applet.Applet applets. Our problem was
+that we also wanted it to be possible to quickly adapt these applets to JavaScript as well.
+
+The solution turned out to be simple: Write a package (a2s) that recreates the interface for
+non-Swing components as subclasses of Swing components. Thus, a2s.Button subclasses javax.swing.JButton
+but also accepts all of the methods of java.awt.Button. This works amazingly well, with a few
+special adaptations to the core javax.swing to be "AWT-aware." All AWT components now subclass
+a2s components, which in turn subclass JComponents. So no changes in code are necessary. We have
+successfully transpiled over 500 applets using this strategy. (Kind of surprising, actually, that
+the original Java developers did not see that option. But we have a hindsight advantage here.)
+
+
+Working with Files
+==================
+
+Simple String file names are not optimal for passing information about
+read files within SwingJS applications.
+
+All work with files should either use Path or File objects exclusively.
+These objects, after a file is read or checked for existence, will already
+contain the file byte[] data. Doing something like this:
+
+File f = File("./test.dat");
+boolean isOK = f.exists();
+
+will load f with its byte[] data, if the file exists.
+
+But if after that, we use:
+
+File f2 = new File(f.getAbsolutePath());
+
+f2 will not contain that data. Such copying should be done as:
+
+File f2 = new File(f);
+
+in which case, the byte[] data will be transferred.
+
+
+SwingJS uses the following criteria to determine if File.exists() returns true:
+
+(1) if this File object has been used directly to read data, or
+(2) if reading data using this File object is successful.
+
+Note that you cannot check to see if a file exists before input or if it
+was actually written or if it already exists prior to writing in SwingJS.
+
+Thus, you should check each use of file.exists() carefully, and if necessary, provide a J2sNative
+block that gives an appropriate "OK" message, for example:
+
+(/** @j2sNative 1 ? false : */ outputfile.exits())
+
+or
+
+(/** @j2sNative 1 ? true : */ inputfile.exits())
+
+Temporary files can be created in SwingJS. SwingJS will maintain a pseudo-filesystem for files
+created with File.createTempFile(). This is useful in that closure of writing to a temporary file
+does not generate a pseudo-download to the user's machine.
+
+
+UNIMPLEMENTED CLASSES BY DESIGN
+===============================
+
+The SwingJS implementation of the following classes are present
+in a way that gracefully bypasses their functionality:
+
+accessibility
+security
+serialization
+
+
+
+TODO LIST FOR UNIMPLEMENTED CLASSES
+===================================
+
+JEditorPane (minimal implementation) - DONE 12/2018; some issues still
+JSplitPane - DONE 8/2018
+JTabbedPane - DONE 10/2018
+JTree - done 12/2019
+
+
+MINOR ISSUES--required some rewriting/refactoring by Bob and Udo
+================================================================
+
+Thread.currentThread() == dispatchThread
+
+
+MINOR ISSUES--requiring some rewriting/refactoring outside of SwingJS
+=====================================================================
+
+See below for a full discussion.
+
+Restrictions on long
+Restriction on BitSet and Scanner
+HashMap, Hashtable, and HashSet iterator ordering
+interning, new String("xxx") vs "xxx"
+Names with "$" and "_"
+positive integers do not add to give negative numbers
+ArrayIndexOutOfBounds
+java.awt.Color
+native methods
+javax.swing.JFileDialog
+key focus
+LookAndFeel and UI Classes
+System.exit(0) does not stop all processes
+list cell renderers must be JComponents
+myClass.getField not implemented
+"window" and other reserved JavaScript names
+reserved field and method names
+qualified field and method names
+missing Math methods
+Component.getGraphics(), Graphics.dispose()
+Graphics.setClip()
+
+MAJOR ISSUES--for Bob and Udo within SwingJS
+============================================
+
+fonts
+OS-dependent classes
+AWT component peers
+some aspects of reflection
+
+MAJOR ISSUES--to be resolved by implementers
+============================================
+
+fonts
+threads
+modal dialogs
+image loading
+BigDecimal not fully implemented
+no format internationalization
+no winding rules
+text-related field implementation
+Formatter/Regex limitations
+integer 1/0 == Infinity
+
+========================================================================
+
+DISCUSS
+=======
+
+Table row/col sorter needs checking after removal of java.text.Collator references
+
+I had to move all of SunHints class to RenderingHints, or the
+two classes could not be loaded. Shouldn't be a problem, I think. The sun classes are
+not accessible to developers in Java anyway, since they are generally package private.
+
+==========================================================================
+
+//////////////////////////////////////////////////////////////////////////////
+
+UNIMPLEMENTED CLASSES
+=====================
+
+accessibility
+-------------
+
+All Accessibility handling has been commented out to save the download footprint.
+This removes the need for sun.misc.SharedSecrets as well.
+Nothing says we could not implement accessibility. We just didn't.
+
+
+security
+--------
+
+All JavaScript security is handled by the browser natively.
+Thus, Java security checking is no longer necessary, and
+java.security.AccessController has been simplified to work without
+native security checking.
+
+Note that private methods in a class are REALLY private.
+
+
+serialization
+-------------
+
+All serialization has been removed. It was never very useful for Swing anyway,
+because one needs exactly the same Java version to save and restore serialized objects.
+
+
+keyboard accelerators and mnemonics
+-----------------------------------
+
+This work was completed in the spring of 2019. Note that in a browser, some
+key strokes, particularly CTRL-keys, are not available. Bummer.
+
+
+MINOR ISSUES--required some rewriting/refactoring by Bob and Udo
+================================================================
+
+
+Thread.currentThread() == dispatchThread
+----------------------------------------
+
+changed to JSToolkit.isDispatchThread()
+
+
+MINOR ISSUES--requiring some rewriting/refactoring outside of SwingJS
+=====================================================================
+
+restrictions on long
+--------------------
+
+Java's 64-bit long type is not supported in JavaScript. There is no Int64Array in JavaScript,
+and 0x20000000000000 + 1 evaluates to 0x20000000000000, not 0x20000000000001.
+(Likewise, -0x20000000000000 - 1 is left unchanged.)
+
+The largest "integer" value in JavaScript is 9007199254740991 (9.007199254740991E13, or 0x1FFFFFFFFFFFFFF).
+Effectively, you get to use only 53 bits of the long, not 64. Trying to set a long larger than
+0x1FFFFFFFFFFFFFF or smaller than -0x1FFFFFFFFFFFFFF will result in a NumberFormatException.
+
+The transpiler handles conversion to long the same as Java for all cases other than from double.
+
+For small double values, there is no problem, and, in fact, this is a known trick used to round
+doubles and floats toward zero:
+
+double d;
+d = (long) 3.8;
+assert(d == 3);
+d = (long) -3.8;
+assert(d == -3);
+
+SwingJS will evaluate (long) d as 0 for d > 9007199254740991
+or d < -9007199254740991, same as Java returns for Double.NaN.
+So, in Java we have:
+
+ assert(((long) Double.NaN) == 0);
+ assert(((int) Double.NaN) == 0);
+ assert(((long) Float.NaN) == 0);
+ assert(((int) Float.NaN) == 0);
+
+and also, in JavaScript only, we also have:
+
+ double d = 0x2000000000000L;
+ assert(((long) d) == 0);
+
+
+restrictions on BitSet and Scanner
+----------------------------------
+
+Because of the issue of long being only 53 bits, any time a method returns a long value, considerations must
+be made as to whether this will work in JavaScript. In particular, BitSet and Scanner have issues.
+
+In SwingJS, java.util.BitSet has been implemented as a 32-bit integer-based bitset. This was no problem in
+Java 6, but starting with Java 7, a method was added to BitSet that allows for the extraction of the
+underlying long[] word data. This is not work in JavaScript. Instead, SwingJS java.util.Bitset.toLongArray() will deliver
+32-bit int[] data.
+
+SwingJS Scanner has hasNextLong() and nextLong(), and although it will scan through long numbers,
+Scanner will choke on long numbers greater than the JavaScript 53-bit limit. hasNextLong() will
+return false, and nextLong() will throw an InputMismatchException triggered by the NumberFormatException
+thrown by Long.parseLong().
+
+
+HashMap, Hashtable, and HashSet iterator ordering
+-------------------------------------------------
+
+In Java, iterators for HashMap, Hashtable, and HashSet do not guarantee any particular order.
+From the HashMap documentation for Java 8:
+
+ This class makes no guarantees as to the order of the map; in particular, it does not
+ guarantee that the order will remain constant over time.
+
+Likewise, for HashSet (because it is simply a convenience method for HashMap<Object,PRESENT>:
+
+ [HashSet] makes no guarantees as to the iteration order of the set.
+
+JavaScript's Map object is different. It is basically a LinkedHashMap, so it guarantees iteration
+in order of object addition.
+
+Starting with java2script 3.2.9.v1, these classes use the JavaScript Map object rather than hash codes
+whenever all keys are strictly of JavaScript typeof "string". If any key is introduced that is not a string, the
+implementation falls back to using hash codes, the same as Java.
+
+Note strings created using new String("xxxx") are NOT typeof "string"; they are typeof "object".
+
+The result is significantly faster performance (3-12 x faster) than originally, and up to 3 x faster
+performance in JavaScript than in Java itself. Right. Faster than Java.
+
+The JavaScript Map implementation is implemented UNLESS the constructor used is the one that
+specifies both initial capacity and load factor in their constructor. Thus,
+
+new Hashtable()
+new HashMap()
+new HashMap(16)
+new HashSet()
+
+all use the JavaScript Map. But
+
+new Hashtable(11, 0.75f)
+new HashMap(16, 0.75f)
+new HashSet(16, 0.75f)
+
+do not.
+
+This design allows for opting out of the JavaScript Map use in order to retain the exact behavior of
+iterators in JavaScript as in Java.
+
+
+interning, new String("xxx") vs "xxx"
+-------------------------------------
+
+Note that the following are true in JavaScript:
+
+typeof new String("xxxx") == "object"
+typeof "xxxx" == "string"
+var s = "x";typeof ("xxx" + s) == "string"
+
+There is no equivalence to this behavior in Java, where a String is a String is a String.
+
+Be aware that SwingJS does not always create a JavaScript String object using JavaScript's
+new String(...) constructor. It only does this for Java new String("xxxx") or new String(new String()).
+
+In all other cases, new String(...) (in Java) results in a simple "xxxx" string in JavaScript.
+That is, it will be JavaScript typeof "string", not typeof "object".
+
+The reason for this design is that several classes in the Java core use toString()
+methods that return new String(), and those classes that do that would cause a JavaScript error
+if implicitly stringified if new String() returned a JavaScript String object.
+
+This is fine in JavaScript
+
+test1 = function() { return { toString:function(){ return "OK" } } }
+"testing" + new test1()
+>> "testingOK"
+
+But for whatever reason in JavaScript:
+
+test2 = function() { return { toString:function(){ return new String("OK") } } }
+"testing" + new test2()
+>> Uncaught TypeError: Cannot convert object to primitive value
+
+The lesson here is never to use
+
+ return new String("...");
+
+in a Java toString() method. In Java it will be fine; in JavaScript it will also be fine as long as
+that method is never called in JavaScript implicitly in the context of string concatenation.
+
+A note about interning. Consider the following six Java constructions, where we have a == "x";
+
+"xxx"
+"xx" + "x"
+new String("xxx").intern()
+
+new String("xxx")
+"xx" + a.toString()
+"xx" + a
+
+All six of these will return java.lang.String for .getClass().getName().
+However, the first three are String literals, while the last three are String objects.
+Thus:
+ "xxx" == "xxx"
+ "xxx" == "xx" + "x"
+ "xxx" == new String("xxx").intern()
+
+but none of the other three are equivalent to "xxx" or each other:
+
+ "xxx" != new String("xxx")
+ "xxx" != "xx" + a.toString()
+ "xxx" != "xx" + a
+ new String("xxx") != new String("xxx")
+ "xx" + a != new String("xxx")
+
+etc.
+
+As in Java, in SwingJS, all of the following Java assertions pass as true:
+
+ assert("xxx" == "xx" + "x");
+ assert("xxx" == ("xx" + a).intern());
+ assert("xxx" === new String("xxx").intern());
+
+and both of these do as well:
+
+ assert(new String("xxx") != "xxx");
+ assert(new String("xxx") != new String("xxx"));
+
+But the following two fail to assert true:
+
+ assert("xxx" != "xx" + a);
+ assert("xxx" != "xx" + a.toString());
+
+because in JavaScript, both of these right-side expressions evaluate to a simple "interned" string.
+
+In Java, however, these assertions are true because Java implicitly "boxes" String
+concatentaion as a String object, not a literal.
+
+Most of us know not to generally use == with Strings unless they are explicitly interned.
+Where this problem may arise, though, is in IdentityHashMap, which compares objects using
+System.identityHashCode(), which is not the same for different objects or their string literal equivalents.
+
+My recommendation, if you need to use IdentityHashMap with strings is to always use an explicit String.intern()
+for any keys -- unless you really want to keep every string as separate keys even if they are the same sequence,
+in which case, use new String(). This will work in Java and in JavaScript.
+
+Be aware when working with strings that come from SwingJS and are being used by other JavaScript modules
+that those that are String objects will return "object" for the JavaScript typeof operator, not "string".
+
+The easy way to ensure this is no problem is to concatenate strings with "" to force immediate interning:
+
+ var x = aJavaObject.getString() + "";
+
+unless you are certain that the string is being returned is a raw JavaScript string.
+
+Names with "$" and "_"
+----------------------
+
+For the most part, this should be no problem.
+
+Note that the use of $ and _ in Java field names has always been discouraged:
+[https://docs.oracle.com/javase/tutorial/java/nutsandbolts/variables.html]
+
+ You may find some situations where auto-generated names will contain the dollar sign,
+ but your variable names should always avoid using it. A similar convention
+ exists for the underscore character; while it's technically legal to begin your
+ variable's name with "_", this practice is discouraged.
+
+Some impacts of transpiling method names with full qualification:
+
+1) SwingJS will introduce fields that start with $ or _. These will not conflict
+ if the above convention is followed.
+
+2) Fields that have the same Java name as a method are not an issue.
+
+3) Fields that have a Java name with $ that matches a transpiled method name,
+ such as toString$, will need to be refactored in Java to not have that name collision.
+
+4) Fields in a subclass that have the same name as private fields in a superclass
+ represent a name collision, because the superclass method needs to call its private
+ field even if invoked from a subclass. The solution was to modify the subclass field
+ name using one or more prepended $.
+
+5) Use of Class.getDeclaredMethods() reflection will return Method objects having the transpiled
+ name, not the Java name. This could require some j2sNative adjustment
+ to strip the $... parameters from the name if that is needed.
+
+6) Use of Method.getParameterTypes() should work fine, provided class names
+ do not contain "_". This is because the transpiler converts "." to "_" when
+ creating the fully qualified JavaScript name.
+
+
+positive integers do not add to give negative numbers
+-----------------------------------------------------
+
+In Java, the following is true:
+
+ 2000000000 + 2000000000 == -294967296
+
+But in SwingJS, that will be 4000000000. So, for example, the following
+strategy will fail in SwingJS:
+
+ int newLength = lineBuf.length * 2;
+ if (newLength < 0) {
+ newLength = Integer.MAX_VALUE;
+ }
+
+"-1" in JavaScript is not 0xFFFFFFFF.
+
+And one must take care to not compare a negative number with a 32-bit mask. So
+
+(b & 0xFF000000) == 0xFF000000
+
+is true in Java for (int) b = -1, but is false in JavaScript, because 0xFF000000 is 4278190080,
+while (-1 & 0xFF000000) is, strangely enough, -16777216, and, in fact,
+
+(0xFF000000 & 0xFF000000) != 0xFF000000
+
+because -16777216 is not 4278190080.
+
+The fix is that one must compare similar operations:
+
+if ((b & 0xFF000000) == (0xFF000000 & 0xFF000000)) .....
+
+Importantly, the JavaScript Int32Array does behave properly. From
+the Firefox developer console:
+
+>> x = new Int32Array(1)
+<- Int32Array(1) [ 0 ]
+>> x[0] = 4000000000
+<- 4000000000
+>> x[0]
+<- -294967296
+
+Notice that, perhaps unexpectedly, the following two constructs produce
+different results in JavaScript:
+
+x = new Int32Array(1);
+b = x[0] = 4000000000;
+
+(b will be 4000000000)
+
+and
+
+x = new Int32Array(1);
+x[0] = 4000000000;
+b = x[0];
+
+(b will be -294967296)
+
+
+SwingJS leverages array typing to handle all byte and short arithmetic so as
+to ensure that any byte or short operation in JavaScript does give the same
+result in Java. The design decision to not also do this with integer math was
+a trade-off between performance and handling edge cases.
+
+
+ArrayIndexOutOfBounds
+---------------------
+
+You cannot implicitly throw an ArrayIndexOutOfBoundsException in JavaScript.
+JavaScript will simply return "undefined", not throw an Exception. So:
+
+boolean notAGoodIdeaIsOutOfBounds(String[] sa, int i) {
+ try {
+ return (sa[i] == sa[i]);
+ } catch (ArrayIndexOutOfBoundsException e) {
+ return false;
+ }
+}
+
+will work in Java but not in JavaScript. Code should not depend upon this sort
+of trap anyway, if you ask me.
+
+Throwable vs Error vs Exception
+-------------------------------
+
+True JavaScript errors are trapped as Throwable, whereas you can still trap
+Error and Exception as well. So if you want to be sure to catch any JavaScript
+error, use try{}catch (Throwable t){}, not try{}catch (Exception e){}.
+
+j
+ava.awt.Color
+--------------
+
+ColorSpace: only "support" CS_sRGB.
+
+ TODO -- any volunteers??
+
+
+javax.swing.JFileDialog
+-----------------------
+
+HTML5 cannot expose a file reading directory structure. But you certainly
+can still do file reading and writing. It just works a little differently.
+It's a simple modification:
+
+ b = new JButton("FileOpenDialog");
+ b.addActionListener(new ActionListener() {
+
+ @Override
+ public void actionPerformed(ActionEvent e) {
+ JFileChooser fc = new JFileChooser();
+ Test_Dialog.this.onDialogReturn(fc.showOpenDialog(Test_Dialog.this));
+ // Java will wait until the dialog is closed, then enter the onDialogReturn method.
+ // JavaScript will exit with NaN immediately, and then call back with its actual value
+ // asynchronously.
+ }
+
+ });
+
+ public void onDialogReturn(int value) {
+ if (value != Math.floor(value))
+ return; // in JavaScript, this will be NaN, indicating the dialog has been opened
+ // If we are here, the dialog has closed, in both Java and JavaScript.
+ System.out.println("int value is " + value);
+ }
+
+
+ @Override
+ public void propertyChange(PropertyChangeEvent event) {
+ Object val = event.getNewValue();
+ String name = event.getPropertyName();
+ System.out.println(name);
+ switch (event.getSource().getClass().getName()) {
+ case "javax.swing.JOptionPane":
+ switch (name) {
+ case "inputValue":
+ onDialogReturn(val);
+ return;
+ case "value":
+ if (val instanceof Integer)
+ onDialogReturn(((Integer) val).intValue());
+ else
+ onDialogReturn(val);
+ return;
+ }
+ break;
+ case "javax.swing.ColorChooserDialog":
+ switch (name) {
+ case "SelectedColor":
+ onDialogReturn(val);
+ return;
+ }
+ break;
+ case "javax.swing.JFileChooser":
+ switch (name) {
+ case "SelectedFile":
+ File file = (File) val;
+ byte[] array = (val == null ? null : /** @j2sNative file.秘bytes || */
+ null);
+ onDialogReturn("fileName is '" + file.getName() + "'\n\n" + new String(array));
+ return;
+ }
+ break;
+ }
+ System.out.println(
+ event.getSource().getClass().getName() + " " + event.getPropertyName() + ": " + event.getNewValue());
+ }
+
+
+Developers are encouraged to create a separate class that handles general calls to JFileDialog.
+An example class can be found in the SwingJS distribution as
+
+/sources/net.sf.j2s.java.core/src/javajs/async/AsyncFileChooser.java.
+
+
+javax.swing.JOptionPane dialogs
+-------------------------------
+
+For this action to work, the parentComponent must implement
+propertyChangeListener, and any call to JOptionPanel should allow for
+an asynchronous response, meaning that there is no actionable code following the
+call to the dialog opening.
+
+In addition, for compatibility with the Java version, implementation should
+wrap the call to getConfirmDialog or getOptionDialog in a method call to
+handle the Java:
+
+onDialogReturn(JOptionPane.showConfirmDialog(parentFrame,
+messageOrMessagePanel, "title", JOptionPane.OK_CANCEL_OPTION));
+
+Then parentFrame.propertyChange(event) should also call onDialogReturn.
+
+This will then work in both Java and JavaScript.
+
+Note that there is an int and an Object version of onDialogReturn().
+
+
+In JavaScript:
+
+The initial return from JOptionPane.showConfirmDialog and showMessageDialog
+will be (SwingJS) JDialog.ASYNCHRONOUS_INTEGER (NaN), testable as an impossible
+Java int value using ret != -(-ret) if the parent implements PropertyChangeListener, or -1
+(CLOSE_OPTION) if not.
+
+For showOptionDialog (which returns Object) or showInputDialog (which returns
+String), the initial return will be (SwingJS) JDialog.ASYNCHRONOUS_OBJECT, testable as
+((Object) ret) instanceof javax.swing.plaf.UIResource if the parent implements
+PropertyChangeListeneer, or null if not.
+
+The second return will be the desired return.
+
+In Java:
+
+The initial return will be the one and only modal final return.
+
+
+
+For full compatibility, The calling method must not continue beyond this
+call.
+
+All of the standard Java events associated with Components are also
+available.
+
+Certain fall back mechanisms are possible, where onReturn does not exist, but
+only for the following cases:
+
+
+For showMessageDialog, for WARNING_MESSAGE and ERROR_MESSAGE, a simple
+JavaScript alert() is used, returning 0 (OK_OPTION) or -1 (CLOSED_OPTION).
+
+For showInputDialog, if the message is a string, a simple JavaScript prompt()
+with input box is used, returning the entered string or null.
+
+For showConfirmDialog, a simple JavaScript confirm() is used, in which case:
+
+for YES_NO_OPTION: YES_OPTION or NO_OPTION
+
+for YES_NO_CANCEL_OPTION: YES_OPTION or CANCEL_OPTION
+
+for OK_CANCEL_OPTION or any other: OK_OPTION or CANCEL_OPTION
+
+Note that you should implement a response for CLOSED_OPTION for
+showConfirmDialog. For other dialogs, a null return indicates the dialog was
+closed, just as for Java.
+
+Developers are encouraged to create a separate class that handles general calls.
+An example class can be found in the SwingJS distribution as src/javajs/async/AsyncDialog.java.
+Very simple modifications to the Java allows asynchronous operation using AsyncDialog. Here
+is a simple "do you want to close this frame" example, where you can see that what we have
+done is to set the reply into an ActionListener that is defined in the constructor of
+the AsyncDisplay object:
+
+// Original:
+//
+// private void promptQuit() {
+// int sel = JOptionPane.showConfirmDialog(null, PROMPT_EXIT, NAME, JOptionPane.YES_NO_OPTION);
+// switch (sel) {
+// case JOptionPane.YES_OPTION:
+// resultsTab.clean();
+// seqs.dispose();
+// if (fromMain) {
+// System.exit(0);
+// }
+// break;
+// }
+// }
+
+ private void promptQuitAsync() {
+ new AsyncDialog(new ActionListener() {
+
+ @Override
+ public void actionPerformed(ActionEvent e) {
+ int sel = ((AsyncDialog)e.getSource()).getOption();
+ switch (sel) {
+ case JOptionPane.YES_OPTION:
+ resultsTab.clean();
+ seqs.dispose();
+ if (fromMain) {
+ System.exit(0);
+ }
+ break;
+ }
+ }}).showConfirmDialog(null, PROMPT_EXIT, NAME, JOptionPane.YES_NO_OPTION);
+ }
+
+Very simple!
+
+
+native methods
+--------------
+
+The J2S compiler ignores all static native method declarations.
+Anything of this nature needs to be implemented in JavaScript if it is needed,
+using j2sNative blocks:
+
+/**
+ * @j2sNative
+ *
+ * var putYourJavaScriptCodeHere
+ *
+ */
+
+ Note that if you follow that directly with a {...} block, then
+ the javadoc code will run in JavaScript, and the {...} code will run in Java.
+
+
+key Focus
+---------
+
+As of June, 2019, the keyboard focus manager is fully implemented.
+The one catch is that JTextPane and JTextArea, which already consume
+VK_TAB in Java, cannot use CTRL-TAB to continue a tabbing cycle around
+the components in a window. Instead, CTRL-TAB is absorbed by the browser.
+
+
+LookAndFeel and UI Classes
+--------------------------
+
+SwingJS implements the native browser look and feel as swingjs.plaf.HTML5LookAndFeel.
+There are small differences between all look and feels -- MacOS, Windows, SwingJS.
+
+Expert developers know how to coerce changes in the UI by subclassing the UI for a
+component. This probably will not work in SwingJS.
+
+Note that LookAndFeel in Java usually determines canvas size in a Frame because
+different operating systems (Mac OS vs Windows vs HTML5) will have
+different edge sizes on their frames. If you want to ensure a component size,
+use getContentPane().setPreferredSize().
+
+
+System.exit(0) does not stop all processes
+------------------------------------------
+
+Although System.ext(int) has been implemented in JavaScript, it just closes the
+frames, stops all pending javax.swing.Timer objects in the queue, and runs any
+threads added using Runtime.getRuntime().addShutdownHook(Thread).
+It may not stop all "threads." So don't rely on that.
+Applications are responsible for shutting down prior to executing System.exit(0).
+
+
+myClass.getField not implemented
+--------------------------------
+
+java.lang.reflect.Field is implemented minimally. It is not
+certain that Field.getDeclaringClass() will work. If you just want a
+value of a field, you can do this:
+
+/**
+ *@j2sNative
+ *
+ * return myClass[name]
+ */
+
+But that is not a java.lang.reflection.Field object.
+
+
+"window" and other reserved JavaScript names
+--------------------------------------------
+
+No reserved top-level JavaScript name is allowed for a package name. So, for example,
+one must rename packages such as "window" or "document" to names such as "win" or "doc".
+
+reserved field and method names
+-------------------------------
+
+In order to minimize the chance of added SwingJS field and method names colliding with ones
+developers might use in subclassing Java classes, we have added U+79D8 (first character of Mandarin
+"secret") to the characters already disrecommended by Java documentation ("$" and "_"). The only problem
+would be if you use that character followed by certain English words in certain classes. For example
+\u79D8canvas for JComponents (in java.awt.JSComponent) and \u79D8byte (in java.io.File).
+
+qualified field and method names
+--------------------------------
+
+Method names in SwingJS are fully qualified, meaning two methods with the same Java name but different
+parameters, such as write(int) and write(double), must not have the same name in JavaScript. (In this
+case, we will have write$I and write$D.) However, in certain cases it may be desirable to leave the
+method names unqualified. In particular, when an interface actually represents a JavaScript object,
+the transpiler can leave a method name unqualified. The default situation for this is a class name
+includes ".api.js" (case-sensitive). This means that any method in any class in a package js within
+a package api, or any private interface js that has an outer interface api, will have all-unqualified
+methods. An example of this is swingjs.plaf.JSComboPopupList, which needs to communicate with a jQuery
+object directly using the following interface:
+
+ private interface api {
+
+ interface js extends JQueryObject {
+
+ abstract js j2sCB(Object options);
+
+ abstract Object[] j2sCB(String method);
+
+ abstract Object[] j2sCB(String method, Object o);
+
+ abstract Object[] j2sCB(String method, int i);
+
+ abstract int j2sCB(String OPTION, String name);
+
+ }
+ }
+
+Notice that all these variants of j2sCB() will call the same method in JavaScript by design.
+
+
+missing Math methods
+--------------------
+
+java.lang.Math is worked out, but some methods are missing, either because they
+involve long integer value that are inaccessible in JavaScript, or because I just
+didn't implement them. This is a result of continued Java development.
+It is easy enough to add these methods if you have the source. They go into j2sClazz.js,
+which is combined with other initial libraries into swingjs2.js by build_site.xml
+
+
+Component.getGraphics(), Graphics.dispose()
+-------------------------------------------
+
+Use of component.getGraphics() is discouraged in Java and in SwingJS.
+Specifically in SwingJS, any call to component.getGraphics() or
+BufferedImage.createGraphics() or Graphics.create(...) should be matched with graphics.dispose(),
+particularly when it is called outside the context of a paint(Graphics)
+call from the system.
+
+If you see your graphics scrolling down the page with each repaint,
+look for where you have used Component.getGraphics() and not Graphics.dispose().
+For example, this will definitely NOT work in SwingJS:
+
+ this.paint(getGraphics())
+
+and really should not work in Java, either, as it is technically a resource memory leak.
+
+Instead, if you really do not want to use repaint(), use this:
+
+ Graphics g = getGraphics();
+ paint(g);
+ g.dispose();
+
+
+
+Graphics.setClip()
+------------------
+
+The HTML5 canvas.clip() method is permanent. You can only reset the clip using
+save/restore. This is different from Java, where you can temporarily change it using
+
+ Shape oldClip = Graphics.getClip();
+ Graphics.setClip(newClip);
+ ...
+ Graphics.setClip(oldClip);
+
+If you need to do something like this, you must schedule the paints
+to not have overlapping clip needs.
+
+
+MAJOR ISSUES--for Bob and Udo within SwingJS
+============================================
+
+fonts
+-----
+
+Fonts and FontMetrics will all be handled in JavaScript. Font matching will
+not be exact, and composite (drawn) fonts will not be supported.
+
+SwingJS handles calls such as font.getFontMetrics(g).stringWidth("xxx") by
+creating a <div> containing that text, placing it in an obscure location on
+the page, and reading div.getBoundingClientRect(). This is a VERY precise
+value, but can be a pixel or two off from what Java reports for the same font.
+
+
+OS-dependent classes
+--------------------
+
+Static classes such as:
+
+ java.awt.Toolkit
+ java.awt.GraphicsEnvironment
+
+
+which are created using Class.forName are implemented using classes in the swingjs package.
+
+AWTAccessor is not implemented.
+
+
+AWT component peers and component "ui" user interfaces
+------------------------------------------------------
+
+ComponentPeer is a class that represents a native AWT component.
+Components with such peers are called "heavy-weight" components.
+They are expected to do the dirty work of graphics drawing.
+
+Java Swing implements peers only for JApplet, JDialog, JFrame, and JWindow.
+References to such objects have been removed, but clearly there must be
+some connection to similar DOM objects, even for "light-weight" components.
+
+
+
+MAJOR ISSUES--to be resolved by implementers
+============================================
+
+fonts
+-----
+
+Glyph/composite/outline fonts are not supported.
+
+
+
+threads
+-------
+
+Thread locking and synchronization are not relevant to JavaScript.
+Thus, anything requiring "notify.." or "waitFor.." could be a serious issue.
+
+All threading must be "faked" in JavaScript. Specifically not available is:
+
+ Thread.sleep()
+
+javax.swing.AbstractButton#doClick(pressTime) will not work, as it requires Thread.sleep();
+
+However, java.lang.Thread itself is implemented and used extensively.
+
+Methods thread.start() and thread.run() both work fine.
+
+For simple applications that use Thread.sleep() just to have a delay, as in a frame rate, for
+example, one can use javax.swing.Timer instead. That is fully implemented.
+
+Likewise, java.util.Timer can be replaced with no loss of performance with javax.Swing.Timer.
+Note that java.util.TimerTask is implemented, but it can also be replaced by an implementation of Runnable.
+
+task = new TimerTask(){....};
+t = new java.util.Timer();
+t.schedule(task, 0, 1);
+
+becomes
+
+task = new TimerTask(){....}; // or task = new Runnable() {...}
+t = new javax.swing.Timer(1, new ActionListener() {
+ @Override
+ public void actionPerformed(ActionEvent e) {
+ task.run();
+ }
+};
+t.setInitialDelay(0); // not particularly necessary
+t.start();
+
+In addition, SwingJS provides swingjs.JSThread, which can be subclassed
+if desired. This class allows simple
+
+ while(!interrupted()){
+ wait()
+ ...
+ }
+
+action through an asynchronous function run1(mode). For example:
+
+ protected void run1(int mode) {
+ try {
+ while (true)
+ switch (mode) {
+ case INIT:
+ // once-through stuff here
+ mode = LOOP;
+ break;
+ case LOOP:
+ if (!doDispatch || isInterrupted()) {
+ mode = DONE;
+ } else {
+ Runnable r = new Runnable() {
+ public void run() {
+ // put the loop code here
+ }
+ };
+ dispatchAndReturn(r);
+ if (isJS)
+ return;
+ }
+ break;
+ // add more cases as needed
+ case DONE:
+ // finish up here
+ if (isInterrupted())
+ return;
+ // or here
+ break;
+ }
+ } finally {
+ // stuff here to be executed after each loop in JS or at the end in Java
+ }
+ }
+
+image loading
+-------------
+- All image loading in SwingJS is synchronous. A MediaTracker call will immediately return "complete".
+ However, it still may take one system clock tick to fully load images. Thus, it is recommended that
+ images be preloaded in the static block of the applet if it is necessary that they be available in init().
+ This is only an issue if you are trying to access the pixel buffer of the image in JavaScript.
+
+- Applet.getImage(path, name) will return null if the image does not exist.
+
+- BufferedImage: only "support" imageType RGB and ARGB
+
+ -BH: This is a temporary edit, just to get us started. Certainly GRAY will be needed
+
+
+BigInteger and BigDecimal
+-------------------------
+
+java.math.BigInteger is fully supported; java.math.BigDecimal is roughed
+in and not fully tested (07/2019).
+
+Both classes present significant issues for JavaScript, as they are based in
+Java's 64-bit long for all their operations. Here is the JavaDoc note I added
+to BigInteger:
+
+ * SwingJS note: Because of the limitations of JavaScript with regard
+ * to long-integer bit storage as a double, this implementation drops
+ * the integer storage bit length to 24, giving 48 for long and leaving
+ * the last 16 bits clear for the exponent of the double number. This should
+ * not affect performance significantly. It does increase the storage
+ * size by about 33%. By bringing an "int" to 3 bytes, we can easily construct
+ * and use byte[] data intended for the original BitSet.
+
+"Easily" may be a bit strong there. This was a serious challenge.
+
+BigDecimal seems to run normally, but in order to do that, my hack involves
+reducing the size of an integer that is allowed to be stored as such and not
+in byte[] as a BigInteger. I'm sure there is a performance hit, but it does work.
+
+no format internationalization
+------------------------------
+
+For now, just en for number and date formatters
+
+no winding rules
+----------------
+
+ When filling a graphic, only nonzero winding rule is implemented in HTML5 Canvas2D.
+
+
+
+text-related field implementation
+---------------------------------
+
+Text fields are:
+
+JTextField (JavaScript <input type="text">)
+JTextArea (JavaScript <textarea>)
+JTextPane (JavaScript <div>)
+JEditorPane (JavaScript <div>)
+
+For the initial implementation, we don't implement infinite undo/redo, and the abstract
+document model is much less elaborate. Only PlainDocument (in the form of JSPlainDocument)
+is implemented. The Document returned by JTextField.getDocument() is a javax.swing.text.Document.
+
+All scrolling is handled by HTML5. javax.swing.AutoScroller is not implemented.
+public static methods .stop, .isRunning, .processMouseDragged require true Java threading
+and so are not implmented. javax.swing.text.View and its subclasses are not implemented.
+
+The JS document model does not allow two text fields to address the same underlying document.
+
+JavaScript is slightly different from Java in that the field value is changed asynchronously after
+the keypressed event, so Java actions that are keyed to KEY_PRESSED may not pick up the new
+key value even after SwingUtilities.invokeLater() is called. Thus, key pressed actions may need
+to be recorded after a key released event instead.
+
+Formatter/Regex limitations
+---------------------------
+
+Some browsers cannot process Regex "look-behind" process such as (?<=\W)
+java.util.regex.Matcher and Pattern use JavaScript's RegExp object rather than
+the native Java object. These are not identical. Only flags /igm are supported.
+Matcher.start(groupID) is not supported.
+
+java.util.Formatter will function correctly for all standard %... patterns.
+
+integer 1/0 == Infinity
+-----------------------
+
+1/0 in Java throws "java.lang.ArithmeticException: / by zero", but in JavaScript is just Infinity.
+
+
+
+Summary
+-------
+
+These are all the known limitations of SwingJS. We have not found any of these limitations
+to be show-stoppers. The primary issue for newcomers to SwingJS is having the source code.
+You must check that source code for all your library jar files is available or, if you
+choose, you will need to decompile those classes. We have used decompilation on some projects,
+and it works just fine. So, technically, all we really need are JAR/class files. But the
+source is by far superior. It's generally prettier, and it has the license information that
+may or may not be present with the JAR or class files. Use class files at your own risk.
+
+Bob Hanson
+2019.08.16
+
+
+Additional Issues
+-----------------
+
+Annotation is working for classes, methods, and fields (12/22/19). Method reflection, however,
+is limited. Interfaces do not expose their methods, as the transpiler does not actually transpile
+the interfaces themselves. And method reflection only includes annotated methods.
+
+java.util.concurrent is not fully elaborated. This package is rewritten to not actually use the
+memory handling capabilities of concurrency, which JavaScript does not have access to.
+
+System.getProperties() just returns a minimal set of properties.
+
+
--- /dev/null
+20201222130056
+++ /dev/null
-20191108205610
sun/swing/DefaultLookup.js
sun/swing/SwingLazyValue.js
sun/text/resources/FormatData.js
-sun/text/resources/FormatData_en.js
+sun/text/resources/en/FormatData_en.js
sun/util/resources/LocaleData.js
+sun/util/locale/BaseLocale.js
+sun/util/locale/LocaleUtils.js
+sun/util/locale/provider/LocaleProviderAdapter.js
+sun/util/locale/provider/LocaleDataMetaInfo.js
swingjs/a2s/A2SContainer.js
swingjs/a2s/A2SEvent.js
swingjs/a2s/A2SListener.js
--- /dev/null
+Notes
+=====
+
+---IMPORTANT CHARACTER SET NOTE---
+
+It is critical that all development work in Java2Script
+be done in UTF-8. This means:
+
+- making sure your Eclipse project is set up for UTF-8 (not the Eclipse default?)
+- making sure your server can serve up UTF-8 by default for any browser-loaded files
+- making sure you don't edit a Java2Script class file or one of the site .js files
+ using a non-UTF-8 editor. It may replace non-Latin characters with "?" or garbage.
+- making sure that your web pages are delivered with proper headings indicating HTML5 and UTF-8
+
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="utf-8">
+
+Note that the DOCTYPE tag is critical for some browsers to switch into HTML5 mode. (MSIE?)
+
+
+
+
+In particular, the Mandarin character 秘 (mi; "secret") is used extensively throughout
+the SwingJS class files to distinguish j2s-specific fields and methods that must not
+ever be shadowed or overridden by subclasses. For example, we see in java.lang.Thread.java:
+
+ public static JSThread 秘thisThread;
+
+----------------------------------
+
+
+updated 12/6/2020 -- note about restrictions on long, including BitSet and Scanner
+updated 3/21/2020 -- adds note about HashMap, Hashtable, and HashSet iterator ordering
+updated 3/20/2020 -- adds note about interning, new String("xxx"), and "xxx"
+updated 2/26/2020 -- adds Graphics.setClip issue
+updated 12/22/19 -- additional issues
+updated 11/03/19 -- adds information about File.exists() and points to src/javajs/async
+updated 10/26/19 -- adds information about File.createTempFile()
+updated 8/16/19 -- minor typos and added summary paragraph
+updated 7/19/19 -- clarification that AWT and Swing classes are supported directly
+updated 5/13/19 -- Mandarin U+79D8 reserved character; Missing Math methods; int and long
+updated 5/10/19 -- adds a section on static issues in multi-(duplicate)-applet pages
+updated 1/4/19 -- nio
+updated 9/15/18 -- adds integer 1/0 == Infinity
+updated 7/24/18 -- most classes replaced with https://github.com/frohoff/jdk8u-jdk
+updated 6/5/17 -- reserved package name "window"
+updated 3/11/17 -- myClass.getField
+updated 3/7/17 -- overloading of JSplitPane.setDividerLocation
+updated 3/2/17 -- more indication of classes not implemented (KeyListener)
+
+=============================================================================
+SwingJS and OpenJDK 8+
+=============================================================================
+
+SwingJS implements a wide range of the Java language in JavaScript. The base
+version for this implementation is OpenJDK8. some classes are implemented using
+older source code, and there are some missing methods. For the most part, this is
+no real problem. You can add or modify any java class just be adding it as source
+in your project. Or (preferably) you can contact me, and I can get it into the
+distribution. Or (even more preferably) you can do that via a patch submission.
+
+=================
+DESIGN PHILOSOPHY
+=================
+
+The java2script/SwingJS design goal is to recreate a recognizable, easily debuggable
+equivalent in JavaScript for as much of Java as practical. This means, for example,
+that one can call in JavaScript
+
+ new java.util.Hashtable()
+
+and for all practical purposes it will appear that Java is running.
+
+
+Method and Field Disambiguation
+-------------------------------
+
+SwingJS has no problem with the overloading of methods, for example:
+
+ public void print(int b);
+ public void print(float b);
+
+JavaScript does not allow overloading of methods, and the common practice in
+Java of naming a field the same as a method -- isAllowed and isAllowed() -- is
+not possible in JavaScript. As a result, SwingJS implements "fully-qualified"
+method names using "$" parameter type separation. Thus, these methods in SwingJS
+will be referred to as print$I and print$F. The rules for this encoding are
+relatively simple:
+
+1. The seven primitive types in Java are encoded $I (int), $L (long), $F (float),
+$D (double), $B (byte) $Z (boolean), and $H (short).
+
+2. String and Object are encoded as $S and $O, respectively.
+
+3. "java_lang_" is dropped for all other classes in the java.lang package (as in Java).
+ For example: $StringBuffer, not $java_lang_StringBuffer
+
+4. All other classes are encoded as
+
+ "$" + Class.getName().replace(".","_")
+
+For example, in Java we see:
+
+ public void equals(Object o) {...}
+
+Whereas in SwingJS we have:
+
+ Clazz.newMeth(C$, 'equals$O', function (o) {...}
+
+And
+
+ this.getContentPane().add(bar, "North");
+
+becomes
+
+ this.getContentPane$().add$java_awt_Component$O(bar, "North");
+
+5. Arrays are indicated with appended "A" for each level. So
+
+ setDataVector(Object[][] dataVector, Object[] columnIdentifiers)
+
+becomes
+
+ setDataVector$OAA$OA(dataVector, columnIdentifiers)
+
+(It is recognized that this design does introduce a bit of ambiguity, in that
+ in principal there could be user class named XA and X in the same package,
+ and methods a(X[]) and a(XA) in the same class that cannot be distinguished.
+ The benefit of this simple system, however, triumphed over the unlikelyhood
+ of that scenario.) The transpiler could be set to flag this possibility.
+
+6. Constructors are prepended with "c$". So
+
+ public JLabel(String text) {...}
+
+becomes:
+
+ Clazz.newMeth(C$, 'c$$S', function (text) {...});
+
+Field disambiguation involves prepending. In Java, a class and its subclass
+can both have the same field name, such as
+
+ boolean visible;
+
+When this happens, it is called "shadowing", and though not recommended, Java allows
+it. The Java2Script transpiler will prepend such shadowing fields with "$" so that the
+subclass instance has both "visible" (for use in its methods inherited from its
+superclass) and "$visible" (for its own methods). Thus, we might see in Java:
+
+ this.visible = super.visible;
+
+while in SwingJS we will see:
+
+ this.$visible=this.visible;
+
+since JavaScript does not have the "super" keyword.
+
+
+
+Parameterless methods such as toString() are appended with "$" to become toString$().
+The one exception to this rule is private methods, which are saved in (truly) private
+array in the class (and are not accessible by reflection). Private parameterless
+methods retain their simple Java name, since they cannot conflict with field names.
+
+This renaming of methods has a few consequences, which are discussed more fully below.
+See particularly the section on "qualified field and method names", where it is described
+how you can use packages or classes or interfaces with ".api.js" in them to represent JavaScript
+objects for which all method names are to be left unqualified. Note that it is not
+possible to cherry-pick methods to be unqualified; only full packages, classes or
+interfaces can hold this status.
+
+The swingjs.api.js package in particular contains a number of useful interfaces that
+you can import into your project for JavaScript-specific capabilities.
+
+
+Applet vs. Application
+----------------------
+
+One of the very cool aspects of SwingJS is that it doesn't particularly matter if a browser-based
+Java app is an "applet" or an "application". We don't need JNLP (Java Network Launch Protocol)
+because now we can just start up any Java application in a browser just as easily as any applet.
+The associative array that passes information to the SwingJS applet (information that formerly
+might have been part of the APPLET tag, such as width, height, and codebase, always referred to
+in our writing as "the Info array") allows the option to specify the JApplet/Applet "code"
+class or the application "main" class. Either one will run just fine.
+
+
+Performance
+-----------
+
+Obviously, there are limitations. One is performance, but we have seen reproducible
+performance at 1/6 - 1/3 the speed of Java. Achieving this performance may require
+some refactoring of the Java to make it more efficient in both Java and JavaScript.
+"for" loops need to be more carefully crafted; use of "new" and "instanceof" need to be
+minimized in critical areas. Note that method overloading -- that is, the same method name
+with different parameters, such as read(int) and read(byte) -- is no longer any problem.
+
+
+Threads
+-------
+
+Although there is only a single thread in JavaScript, meaning Thread.wait(), Thread.sleep(int) and
+Thread.notify() cannot be reproduced, we have found that this is not a serious limitation.
+For example, javax.swing.Timer() works perfectly in JavaScript. All it means is that threads
+that use sleep(int) or notify() must be refactored to allow Timer-like callbacks. That is,
+they must allow full exit and re-entry of Thread.run(), not the typical while/sleep motif.
+
+The key is to create a state-based run() that can be exited and re-entered in JavaScript.
+
+
+Static fields
+-------------
+
+Final static primitive "constant" fields (String, boolean, int, etc.) such as
+
+static final int TEST = 3;
+static final String MY_STRING = "my " + "string";
+
+are converted to their primitive form automatically by the Eclipse Java compiler
+and do not appear in the JavaScript by their names.
+
+Other static fields are properties of their class and can be used as expected.
+
+Note, however, that SwingJS runs all "Java" code on a page in a common "jvm"
+(like older versions of Java). So, like the older Java schema, the JavaScript
+equivalents of both applets and applications will share all of their static
+fields and methods. This includes java.lang.System.
+
+Basically, SwingJS implementations of Java run in a browser page-based sandbox
+instead of an applet-specific one.
+
+In general, this is no problem. But if we are to implement pages with
+multiple applets present, we must be sure to only have static references
+that are "final" or specifically meant to be shared in a JavaScript
+environment only (since they will not be shared in Java).
+
+A simple solution, if static non-constant references are needed, is to attach the
+field to Thread.currentThread.threadGroup(), which is an applet-specific reference.
+Be sure, if you do this, that you use explicit setters and getters:
+
+For example,
+
+private static String myvar;
+
+...
+
+public void setMyVar(String x) {
+ ThreadGroup g = Thread.currentThread().threadGroup();
+ /**
+ * @j2sNative g._myvar = x;
+ *
+ */
+ {
+ myvar = x;
+ }
+}
+
+public String getMyVar() {
+ ThreadGroup g = Thread.currentThread().threadGroup();
+ /**
+ * @j2sNative return g._myvar || null;
+ *
+ */
+ {
+ return myvar;
+ }
+}
+
+ in Java will get and set x the same in JavaScript and in Java.
+
+
+A convenient way to do this in general is to supply a singleton class with
+explicitly private-only constructors and then refer to it in Java and in JavaScript
+instead of using static field, referring to myclass.getIntance().xxx instead of
+myclass.xxx in Java (and JavaScript).
+
+This was done extensively in the Jalview project. See jalview.bin.Instance.
+
+
+Helper Packages -- swingjs/ and javajs/
+---------------------------------------
+
+The SwingJS library is the swingjs/ package. There are interfaces that may be of assistance
+in swingjs/api, but other than that, it is not recommended that developers access classes in
+this package. The "public" nature of their methods is really an internal necessity.
+
+In addition to swingjs/, though, there are several useful classes in the javajs/ package
+that could be very useful. This package is a stand-alone package that can be
+cloned in any Java project that also would be great to have in any JavaScript project
+-- SwingJS-related or not. Functionality ranges from reading and writing various file
+formats, including PDF, BMP, PNG, GIF, JPG, JSON, ZIP, and CompoundDocument formats.
+
+A variety of highly efficient three- and four-dimensional point, vector, matrix, and
+quaternion classes are included, as they were developed for JSmol and inherited from that
+project.
+
+Of particular interest should be javajs/async/, which includes
+
+javajs.async.Async
+javajs.async.AsyncColorChooser
+javajs.async.AsyncDialog
+javajs.async.AsyncFileChooser
+
+See javajs.async.Async JavaDoc comments for a full description of
+these useful classes.
+
+
+Modal Dialogs
+-------------
+
+Although true modal dialogs are not possible with only one thread, a functional equivalent --
+asynchronous modal dialogs -- is relatively easy to set up. All the JOptionPane dialogs will
+return PropertyChangeEvents to signal that they have been disposed of and containing the results.
+See below and classes in the javajs.async package.
+
+
+Native calls
+------------
+
+Native calls in Java are calls to operating system methods that are not in Java. JavaScript
+has no access to these, of course, and they must all be replaced by JavaScript equivalents.
+Fortunately, they are not common, and those that are present in Java (for example, in calculating
+checksums in ZIP file creation) are at a low enough level that most developers do not utilize them
+or do not even have access to them. All native calls in Java classes have been replaced by
+Java equivalents.
+
+
+Swing GUI Peers and UIClasses
+-----------------------------
+
+One of the biggest adaptations introduced in SwingJS is in the area of the graphical
+user interface. The issue here is complex but workable. In Java there are two background
+concepts -- the Component "peer" (one per "heavy-weight" component, such as a Frame) and the
+component "uiClass" (one per component, such as JButton or JTextField).
+
+Peers are native objects of the operating system. These are the virtual buttons and text areas
+that the user is interacting with at a very base level. Their events are being passed on to
+Java or the browser by the operating system. UI classes provide a consistent "look and feel"
+for these native objects, rendering them onto the native window canvas and handling all
+user-generated events. They paint the borders, the backgrounds, the highlights, of every
+control you see in Java. There is one-to-one correspondence of Swing classes and UI classes.
+Setting the Look and Feel for a project amounts to selecting the directory from which to draw
+these UI classes. The UI classes can be found in the javax.swing.plaf ("platform look and feel")
+package.
+
+Early on in the development of SwingJS, we decided not to fully reproduce the painfully detailed
+bit-by-bit painting of controls as is done in Java. Instead, we felt it was wiser to utilize the standard
+HTML5 UI capabilities as much as possible, using DIV, and INPUT especially, with extensive use
+of CSS and sometimes jQuery (menus, and sliders, for example). Thus, we have created a new
+set of UIs -- the "HTML5 Look and Feel". These classes can be found in swingjs.plaf. Besides being
+more adaptable, this approach allows far more versatility to SwingJS developers, allowing them
+to modify the GUI to suit their needs if desired.
+
+In SwingJS, since we have no access to native peers except through the browser DOM,
+it seemed logical to merge the peer and UI idea. So instead of having one peer per heavy-weight control and
+one UI class instance for each control type, we just have one UI class instance per control, and
+that UI class instance is what is being referred to when a "peer" is notified.
+
+In some ways this is a throw back to when all of Swing's components were subclasses of
+specific AWT components such as Button and List. These "heavy-weight components" all had their
+own individual native peers and thus automatically took on the look and feel provided by the OS.
+Later Swing versions implemented full look and feel for all peers, leaving only JDialog, JFrame,
+and a few other classes to have native peers. But in SwingJS we have again a 1:1 map of component
+and UI class/peer instance.
+
+The origin of most issues (read "bugs") in relation to the GUI will probably be found in the
+swingjs.plaf JSxxxxUI.java code.
+
+
+Swing-only Components -- no longer an issue
+-------------------------------------------
+
+Swing was introduced into Java well after the Java Abstract Window Toolkit (AWT) was well
+established. As such, its designers chose to allow AWT controls such as Button and List to be used
+alongside their Swing counterparts JButton and JList. Reading the code, it is clear that this
+design choice posed a huge headache for Swing class developers.
+
+For SwingJS, we decided from the beginning NOT to allow this mixed-mode programming and
+instead to require that all components be Swing components.
+
+However, this is no longer an issue. All AWT components in SwingJS are now subclasses of
+javax.swing.JComponent. So far, we have found no problem with this.
+
+
+The a2s Adapter Package
+-----------------------
+
+Originally, we thought that we would restrict ourselves to JApplets only. That is, only
+Swing-based applets. But as we worked, we discovered that there are a lot of great
+applets out there that are pre-Swing pure-AWT java.applet.Applet applets. Our problem was
+that we also wanted it to be possible to quickly adapt these applets to JavaScript as well.
+
+The solution turned out to be simple: Write a package (a2s) that recreates the interface for
+non-Swing components as subclasses of Swing components. Thus, a2s.Button subclasses javax.swing.JButton
+but also accepts all of the methods of java.awt.Button. This works amazingly well, with a few
+special adaptations to the core javax.swing to be "AWT-aware." All AWT components now subclass
+a2s components, which in turn subclass JComponents. So no changes in code are necessary. We have
+successfully transpiled over 500 applets using this strategy. (Kind of surprising, actually, that
+the original Java developers did not see that option. But we have a hindsight advantage here.)
+
+
+Working with Files
+==================
+
+Simple String file names are not optimal for passing information about
+read files within SwingJS applications.
+
+All work with files should either use Path or File objects exclusively.
+These objects, after a file is read or checked for existence, will already
+contain the file byte[] data. Doing something like this:
+
+File f = File("./test.dat");
+boolean isOK = f.exists();
+
+will load f with its byte[] data, if the file exists.
+
+But if after that, we use:
+
+File f2 = new File(f.getAbsolutePath());
+
+f2 will not contain that data. Such copying should be done as:
+
+File f2 = new File(f);
+
+in which case, the byte[] data will be transferred.
+
+
+SwingJS uses the following criteria to determine if File.exists() returns true:
+
+(1) if this File object has been used directly to read data, or
+(2) if reading data using this File object is successful.
+
+Note that you cannot check to see if a file exists before input or if it
+was actually written or if it already exists prior to writing in SwingJS.
+
+Thus, you should check each use of file.exists() carefully, and if necessary, provide a J2sNative
+block that gives an appropriate "OK" message, for example:
+
+(/** @j2sNative 1 ? false : */ outputfile.exits())
+
+or
+
+(/** @j2sNative 1 ? true : */ inputfile.exits())
+
+Temporary files can be created in SwingJS. SwingJS will maintain a pseudo-filesystem for files
+created with File.createTempFile(). This is useful in that closure of writing to a temporary file
+does not generate a pseudo-download to the user's machine.
+
+
+UNIMPLEMENTED CLASSES BY DESIGN
+===============================
+
+The SwingJS implementation of the following classes are present
+in a way that gracefully bypasses their functionality:
+
+accessibility
+security
+serialization
+
+
+
+TODO LIST FOR UNIMPLEMENTED CLASSES
+===================================
+
+JEditorPane (minimal implementation) - DONE 12/2018; some issues still
+JSplitPane - DONE 8/2018
+JTabbedPane - DONE 10/2018
+JTree - done 12/2019
+
+
+MINOR ISSUES--required some rewriting/refactoring by Bob and Udo
+================================================================
+
+Thread.currentThread() == dispatchThread
+
+
+MINOR ISSUES--requiring some rewriting/refactoring outside of SwingJS
+=====================================================================
+
+See below for a full discussion.
+
+Restrictions on long
+Restriction on BitSet and Scanner
+HashMap, Hashtable, and HashSet iterator ordering
+interning, new String("xxx") vs "xxx"
+Names with "$" and "_"
+positive integers do not add to give negative numbers
+ArrayIndexOutOfBounds
+java.awt.Color
+native methods
+javax.swing.JFileDialog
+key focus
+LookAndFeel and UI Classes
+System.exit(0) does not stop all processes
+list cell renderers must be JComponents
+myClass.getField not implemented
+"window" and other reserved JavaScript names
+reserved field and method names
+qualified field and method names
+missing Math methods
+Component.getGraphics(), Graphics.dispose()
+Graphics.setClip()
+
+MAJOR ISSUES--for Bob and Udo within SwingJS
+============================================
+
+fonts
+OS-dependent classes
+AWT component peers
+some aspects of reflection
+
+MAJOR ISSUES--to be resolved by implementers
+============================================
+
+fonts
+threads
+modal dialogs
+image loading
+BigDecimal not fully implemented
+no format internationalization
+no winding rules
+text-related field implementation
+Formatter/Regex limitations
+integer 1/0 == Infinity
+
+========================================================================
+
+DISCUSS
+=======
+
+Table row/col sorter needs checking after removal of java.text.Collator references
+
+I had to move all of SunHints class to RenderingHints, or the
+two classes could not be loaded. Shouldn't be a problem, I think. The sun classes are
+not accessible to developers in Java anyway, since they are generally package private.
+
+==========================================================================
+
+//////////////////////////////////////////////////////////////////////////////
+
+UNIMPLEMENTED CLASSES
+=====================
+
+accessibility
+-------------
+
+All Accessibility handling has been commented out to save the download footprint.
+This removes the need for sun.misc.SharedSecrets as well.
+Nothing says we could not implement accessibility. We just didn't.
+
+
+security
+--------
+
+All JavaScript security is handled by the browser natively.
+Thus, Java security checking is no longer necessary, and
+java.security.AccessController has been simplified to work without
+native security checking.
+
+Note that private methods in a class are REALLY private.
+
+
+serialization
+-------------
+
+All serialization has been removed. It was never very useful for Swing anyway,
+because one needs exactly the same Java version to save and restore serialized objects.
+
+
+keyboard accelerators and mnemonics
+-----------------------------------
+
+This work was completed in the spring of 2019. Note that in a browser, some
+key strokes, particularly CTRL-keys, are not available. Bummer.
+
+
+MINOR ISSUES--required some rewriting/refactoring by Bob and Udo
+================================================================
+
+
+Thread.currentThread() == dispatchThread
+----------------------------------------
+
+changed to JSToolkit.isDispatchThread()
+
+
+MINOR ISSUES--requiring some rewriting/refactoring outside of SwingJS
+=====================================================================
+
+restrictions on long
+--------------------
+
+Java's 64-bit long type is not supported in JavaScript. There is no Int64Array in JavaScript,
+and 0x20000000000000 + 1 evaluates to 0x20000000000000, not 0x20000000000001.
+(Likewise, -0x20000000000000 - 1 is left unchanged.)
+
+The largest "integer" value in JavaScript is 9007199254740991 (9.007199254740991E13, or 0x1FFFFFFFFFFFFFF).
+Effectively, you get to use only 53 bits of the long, not 64. Trying to set a long larger than
+0x1FFFFFFFFFFFFFF or smaller than -0x1FFFFFFFFFFFFFF will result in a NumberFormatException.
+
+The transpiler handles conversion to long the same as Java for all cases other than from double.
+
+For small double values, there is no problem, and, in fact, this is a known trick used to round
+doubles and floats toward zero:
+
+double d;
+d = (long) 3.8;
+assert(d == 3);
+d = (long) -3.8;
+assert(d == -3);
+
+SwingJS will evaluate (long) d as 0 for d > 9007199254740991
+or d < -9007199254740991, same as Java returns for Double.NaN.
+So, in Java we have:
+
+ assert(((long) Double.NaN) == 0);
+ assert(((int) Double.NaN) == 0);
+ assert(((long) Float.NaN) == 0);
+ assert(((int) Float.NaN) == 0);
+
+and also, in JavaScript only, we also have:
+
+ double d = 0x2000000000000L;
+ assert(((long) d) == 0);
+
+
+restrictions on BitSet and Scanner
+----------------------------------
+
+Because of the issue of long being only 53 bits, any time a method returns a long value, considerations must
+be made as to whether this will work in JavaScript. In particular, BitSet and Scanner have issues.
+
+In SwingJS, java.util.BitSet has been implemented as a 32-bit integer-based bitset. This was no problem in
+Java 6, but starting with Java 7, a method was added to BitSet that allows for the extraction of the
+underlying long[] word data. This is not work in JavaScript. Instead, SwingJS java.util.Bitset.toLongArray() will deliver
+32-bit int[] data.
+
+SwingJS Scanner has hasNextLong() and nextLong(), and although it will scan through long numbers,
+Scanner will choke on long numbers greater than the JavaScript 53-bit limit. hasNextLong() will
+return false, and nextLong() will throw an InputMismatchException triggered by the NumberFormatException
+thrown by Long.parseLong().
+
+
+HashMap, Hashtable, and HashSet iterator ordering
+-------------------------------------------------
+
+In Java, iterators for HashMap, Hashtable, and HashSet do not guarantee any particular order.
+From the HashMap documentation for Java 8:
+
+ This class makes no guarantees as to the order of the map; in particular, it does not
+ guarantee that the order will remain constant over time.
+
+Likewise, for HashSet (because it is simply a convenience method for HashMap<Object,PRESENT>:
+
+ [HashSet] makes no guarantees as to the iteration order of the set.
+
+JavaScript's Map object is different. It is basically a LinkedHashMap, so it guarantees iteration
+in order of object addition.
+
+Starting with java2script 3.2.9.v1, these classes use the JavaScript Map object rather than hash codes
+whenever all keys are strictly of JavaScript typeof "string". If any key is introduced that is not a string, the
+implementation falls back to using hash codes, the same as Java.
+
+Note strings created using new String("xxxx") are NOT typeof "string"; they are typeof "object".
+
+The result is significantly faster performance (3-12 x faster) than originally, and up to 3 x faster
+performance in JavaScript than in Java itself. Right. Faster than Java.
+
+The JavaScript Map implementation is implemented UNLESS the constructor used is the one that
+specifies both initial capacity and load factor in their constructor. Thus,
+
+new Hashtable()
+new HashMap()
+new HashMap(16)
+new HashSet()
+
+all use the JavaScript Map. But
+
+new Hashtable(11, 0.75f)
+new HashMap(16, 0.75f)
+new HashSet(16, 0.75f)
+
+do not.
+
+This design allows for opting out of the JavaScript Map use in order to retain the exact behavior of
+iterators in JavaScript as in Java.
+
+
+interning, new String("xxx") vs "xxx"
+-------------------------------------
+
+Note that the following are true in JavaScript:
+
+typeof new String("xxxx") == "object"
+typeof "xxxx" == "string"
+var s = "x";typeof ("xxx" + s) == "string"
+
+There is no equivalence to this behavior in Java, where a String is a String is a String.
+
+Be aware that SwingJS does not always create a JavaScript String object using JavaScript's
+new String(...) constructor. It only does this for Java new String("xxxx") or new String(new String()).
+
+In all other cases, new String(...) (in Java) results in a simple "xxxx" string in JavaScript.
+That is, it will be JavaScript typeof "string", not typeof "object".
+
+The reason for this design is that several classes in the Java core use toString()
+methods that return new String(), and those classes that do that would cause a JavaScript error
+if implicitly stringified if new String() returned a JavaScript String object.
+
+This is fine in JavaScript
+
+test1 = function() { return { toString:function(){ return "OK" } } }
+"testing" + new test1()
+>> "testingOK"
+
+But for whatever reason in JavaScript:
+
+test2 = function() { return { toString:function(){ return new String("OK") } } }
+"testing" + new test2()
+>> Uncaught TypeError: Cannot convert object to primitive value
+
+The lesson here is never to use
+
+ return new String("...");
+
+in a Java toString() method. In Java it will be fine; in JavaScript it will also be fine as long as
+that method is never called in JavaScript implicitly in the context of string concatenation.
+
+A note about interning. Consider the following six Java constructions, where we have a == "x";
+
+"xxx"
+"xx" + "x"
+new String("xxx").intern()
+
+new String("xxx")
+"xx" + a.toString()
+"xx" + a
+
+All six of these will return java.lang.String for .getClass().getName().
+However, the first three are String literals, while the last three are String objects.
+Thus:
+ "xxx" == "xxx"
+ "xxx" == "xx" + "x"
+ "xxx" == new String("xxx").intern()
+
+but none of the other three are equivalent to "xxx" or each other:
+
+ "xxx" != new String("xxx")
+ "xxx" != "xx" + a.toString()
+ "xxx" != "xx" + a
+ new String("xxx") != new String("xxx")
+ "xx" + a != new String("xxx")
+
+etc.
+
+As in Java, in SwingJS, all of the following Java assertions pass as true:
+
+ assert("xxx" == "xx" + "x");
+ assert("xxx" == ("xx" + a).intern());
+ assert("xxx" === new String("xxx").intern());
+
+and both of these do as well:
+
+ assert(new String("xxx") != "xxx");
+ assert(new String("xxx") != new String("xxx"));
+
+But the following two fail to assert true:
+
+ assert("xxx" != "xx" + a);
+ assert("xxx" != "xx" + a.toString());
+
+because in JavaScript, both of these right-side expressions evaluate to a simple "interned" string.
+
+In Java, however, these assertions are true because Java implicitly "boxes" String
+concatentaion as a String object, not a literal.
+
+Most of us know not to generally use == with Strings unless they are explicitly interned.
+Where this problem may arise, though, is in IdentityHashMap, which compares objects using
+System.identityHashCode(), which is not the same for different objects or their string literal equivalents.
+
+My recommendation, if you need to use IdentityHashMap with strings is to always use an explicit String.intern()
+for any keys -- unless you really want to keep every string as separate keys even if they are the same sequence,
+in which case, use new String(). This will work in Java and in JavaScript.
+
+Be aware when working with strings that come from SwingJS and are being used by other JavaScript modules
+that those that are String objects will return "object" for the JavaScript typeof operator, not "string".
+
+The easy way to ensure this is no problem is to concatenate strings with "" to force immediate interning:
+
+ var x = aJavaObject.getString() + "";
+
+unless you are certain that the string is being returned is a raw JavaScript string.
+
+Names with "$" and "_"
+----------------------
+
+For the most part, this should be no problem.
+
+Note that the use of $ and _ in Java field names has always been discouraged:
+[https://docs.oracle.com/javase/tutorial/java/nutsandbolts/variables.html]
+
+ You may find some situations where auto-generated names will contain the dollar sign,
+ but your variable names should always avoid using it. A similar convention
+ exists for the underscore character; while it's technically legal to begin your
+ variable's name with "_", this practice is discouraged.
+
+Some impacts of transpiling method names with full qualification:
+
+1) SwingJS will introduce fields that start with $ or _. These will not conflict
+ if the above convention is followed.
+
+2) Fields that have the same Java name as a method are not an issue.
+
+3) Fields that have a Java name with $ that matches a transpiled method name,
+ such as toString$, will need to be refactored in Java to not have that name collision.
+
+4) Fields in a subclass that have the same name as private fields in a superclass
+ represent a name collision, because the superclass method needs to call its private
+ field even if invoked from a subclass. The solution was to modify the subclass field
+ name using one or more prepended $.
+
+5) Use of Class.getDeclaredMethods() reflection will return Method objects having the transpiled
+ name, not the Java name. This could require some j2sNative adjustment
+ to strip the $... parameters from the name if that is needed.
+
+6) Use of Method.getParameterTypes() should work fine, provided class names
+ do not contain "_". This is because the transpiler converts "." to "_" when
+ creating the fully qualified JavaScript name.
+
+
+positive integers do not add to give negative numbers
+-----------------------------------------------------
+
+In Java, the following is true:
+
+ 2000000000 + 2000000000 == -294967296
+
+But in SwingJS, that will be 4000000000. So, for example, the following
+strategy will fail in SwingJS:
+
+ int newLength = lineBuf.length * 2;
+ if (newLength < 0) {
+ newLength = Integer.MAX_VALUE;
+ }
+
+"-1" in JavaScript is not 0xFFFFFFFF.
+
+And one must take care to not compare a negative number with a 32-bit mask. So
+
+(b & 0xFF000000) == 0xFF000000
+
+is true in Java for (int) b = -1, but is false in JavaScript, because 0xFF000000 is 4278190080,
+while (-1 & 0xFF000000) is, strangely enough, -16777216, and, in fact,
+
+(0xFF000000 & 0xFF000000) != 0xFF000000
+
+because -16777216 is not 4278190080.
+
+The fix is that one must compare similar operations:
+
+if ((b & 0xFF000000) == (0xFF000000 & 0xFF000000)) .....
+
+Importantly, the JavaScript Int32Array does behave properly. From
+the Firefox developer console:
+
+>> x = new Int32Array(1)
+<- Int32Array(1) [ 0 ]
+>> x[0] = 4000000000
+<- 4000000000
+>> x[0]
+<- -294967296
+
+Notice that, perhaps unexpectedly, the following two constructs produce
+different results in JavaScript:
+
+x = new Int32Array(1);
+b = x[0] = 4000000000;
+
+(b will be 4000000000)
+
+and
+
+x = new Int32Array(1);
+x[0] = 4000000000;
+b = x[0];
+
+(b will be -294967296)
+
+
+SwingJS leverages array typing to handle all byte and short arithmetic so as
+to ensure that any byte or short operation in JavaScript does give the same
+result in Java. The design decision to not also do this with integer math was
+a trade-off between performance and handling edge cases.
+
+
+ArrayIndexOutOfBounds
+---------------------
+
+You cannot implicitly throw an ArrayIndexOutOfBoundsException in JavaScript.
+JavaScript will simply return "undefined", not throw an Exception. So:
+
+boolean notAGoodIdeaIsOutOfBounds(String[] sa, int i) {
+ try {
+ return (sa[i] == sa[i]);
+ } catch (ArrayIndexOutOfBoundsException e) {
+ return false;
+ }
+}
+
+will work in Java but not in JavaScript. Code should not depend upon this sort
+of trap anyway, if you ask me.
+
+Throwable vs Error vs Exception
+-------------------------------
+
+True JavaScript errors are trapped as Throwable, whereas you can still trap
+Error and Exception as well. So if you want to be sure to catch any JavaScript
+error, use try{}catch (Throwable t){}, not try{}catch (Exception e){}.
+
+j
+ava.awt.Color
+--------------
+
+ColorSpace: only "support" CS_sRGB.
+
+ TODO -- any volunteers??
+
+
+javax.swing.JFileDialog
+-----------------------
+
+HTML5 cannot expose a file reading directory structure. But you certainly
+can still do file reading and writing. It just works a little differently.
+It's a simple modification:
+
+ b = new JButton("FileOpenDialog");
+ b.addActionListener(new ActionListener() {
+
+ @Override
+ public void actionPerformed(ActionEvent e) {
+ JFileChooser fc = new JFileChooser();
+ Test_Dialog.this.onDialogReturn(fc.showOpenDialog(Test_Dialog.this));
+ // Java will wait until the dialog is closed, then enter the onDialogReturn method.
+ // JavaScript will exit with NaN immediately, and then call back with its actual value
+ // asynchronously.
+ }
+
+ });
+
+ public void onDialogReturn(int value) {
+ if (value != Math.floor(value))
+ return; // in JavaScript, this will be NaN, indicating the dialog has been opened
+ // If we are here, the dialog has closed, in both Java and JavaScript.
+ System.out.println("int value is " + value);
+ }
+
+
+ @Override
+ public void propertyChange(PropertyChangeEvent event) {
+ Object val = event.getNewValue();
+ String name = event.getPropertyName();
+ System.out.println(name);
+ switch (event.getSource().getClass().getName()) {
+ case "javax.swing.JOptionPane":
+ switch (name) {
+ case "inputValue":
+ onDialogReturn(val);
+ return;
+ case "value":
+ if (val instanceof Integer)
+ onDialogReturn(((Integer) val).intValue());
+ else
+ onDialogReturn(val);
+ return;
+ }
+ break;
+ case "javax.swing.ColorChooserDialog":
+ switch (name) {
+ case "SelectedColor":
+ onDialogReturn(val);
+ return;
+ }
+ break;
+ case "javax.swing.JFileChooser":
+ switch (name) {
+ case "SelectedFile":
+ File file = (File) val;
+ byte[] array = (val == null ? null : /** @j2sNative file.秘bytes || */
+ null);
+ onDialogReturn("fileName is '" + file.getName() + "'\n\n" + new String(array));
+ return;
+ }
+ break;
+ }
+ System.out.println(
+ event.getSource().getClass().getName() + " " + event.getPropertyName() + ": " + event.getNewValue());
+ }
+
+
+Developers are encouraged to create a separate class that handles general calls to JFileDialog.
+An example class can be found in the SwingJS distribution as
+
+/sources/net.sf.j2s.java.core/src/javajs/async/AsyncFileChooser.java.
+
+
+javax.swing.JOptionPane dialogs
+-------------------------------
+
+For this action to work, the parentComponent must implement
+propertyChangeListener, and any call to JOptionPanel should allow for
+an asynchronous response, meaning that there is no actionable code following the
+call to the dialog opening.
+
+In addition, for compatibility with the Java version, implementation should
+wrap the call to getConfirmDialog or getOptionDialog in a method call to
+handle the Java:
+
+onDialogReturn(JOptionPane.showConfirmDialog(parentFrame,
+messageOrMessagePanel, "title", JOptionPane.OK_CANCEL_OPTION));
+
+Then parentFrame.propertyChange(event) should also call onDialogReturn.
+
+This will then work in both Java and JavaScript.
+
+Note that there is an int and an Object version of onDialogReturn().
+
+
+In JavaScript:
+
+The initial return from JOptionPane.showConfirmDialog and showMessageDialog
+will be (SwingJS) JDialog.ASYNCHRONOUS_INTEGER (NaN), testable as an impossible
+Java int value using ret != -(-ret) if the parent implements PropertyChangeListener, or -1
+(CLOSE_OPTION) if not.
+
+For showOptionDialog (which returns Object) or showInputDialog (which returns
+String), the initial return will be (SwingJS) JDialog.ASYNCHRONOUS_OBJECT, testable as
+((Object) ret) instanceof javax.swing.plaf.UIResource if the parent implements
+PropertyChangeListeneer, or null if not.
+
+The second return will be the desired return.
+
+In Java:
+
+The initial return will be the one and only modal final return.
+
+
+
+For full compatibility, The calling method must not continue beyond this
+call.
+
+All of the standard Java events associated with Components are also
+available.
+
+Certain fall back mechanisms are possible, where onReturn does not exist, but
+only for the following cases:
+
+
+For showMessageDialog, for WARNING_MESSAGE and ERROR_MESSAGE, a simple
+JavaScript alert() is used, returning 0 (OK_OPTION) or -1 (CLOSED_OPTION).
+
+For showInputDialog, if the message is a string, a simple JavaScript prompt()
+with input box is used, returning the entered string or null.
+
+For showConfirmDialog, a simple JavaScript confirm() is used, in which case:
+
+for YES_NO_OPTION: YES_OPTION or NO_OPTION
+
+for YES_NO_CANCEL_OPTION: YES_OPTION or CANCEL_OPTION
+
+for OK_CANCEL_OPTION or any other: OK_OPTION or CANCEL_OPTION
+
+Note that you should implement a response for CLOSED_OPTION for
+showConfirmDialog. For other dialogs, a null return indicates the dialog was
+closed, just as for Java.
+
+Developers are encouraged to create a separate class that handles general calls.
+An example class can be found in the SwingJS distribution as src/javajs/async/AsyncDialog.java.
+Very simple modifications to the Java allows asynchronous operation using AsyncDialog. Here
+is a simple "do you want to close this frame" example, where you can see that what we have
+done is to set the reply into an ActionListener that is defined in the constructor of
+the AsyncDisplay object:
+
+// Original:
+//
+// private void promptQuit() {
+// int sel = JOptionPane.showConfirmDialog(null, PROMPT_EXIT, NAME, JOptionPane.YES_NO_OPTION);
+// switch (sel) {
+// case JOptionPane.YES_OPTION:
+// resultsTab.clean();
+// seqs.dispose();
+// if (fromMain) {
+// System.exit(0);
+// }
+// break;
+// }
+// }
+
+ private void promptQuitAsync() {
+ new AsyncDialog(new ActionListener() {
+
+ @Override
+ public void actionPerformed(ActionEvent e) {
+ int sel = ((AsyncDialog)e.getSource()).getOption();
+ switch (sel) {
+ case JOptionPane.YES_OPTION:
+ resultsTab.clean();
+ seqs.dispose();
+ if (fromMain) {
+ System.exit(0);
+ }
+ break;
+ }
+ }}).showConfirmDialog(null, PROMPT_EXIT, NAME, JOptionPane.YES_NO_OPTION);
+ }
+
+Very simple!
+
+
+native methods
+--------------
+
+The J2S compiler ignores all static native method declarations.
+Anything of this nature needs to be implemented in JavaScript if it is needed,
+using j2sNative blocks:
+
+/**
+ * @j2sNative
+ *
+ * var putYourJavaScriptCodeHere
+ *
+ */
+
+ Note that if you follow that directly with a {...} block, then
+ the javadoc code will run in JavaScript, and the {...} code will run in Java.
+
+
+key Focus
+---------
+
+As of June, 2019, the keyboard focus manager is fully implemented.
+The one catch is that JTextPane and JTextArea, which already consume
+VK_TAB in Java, cannot use CTRL-TAB to continue a tabbing cycle around
+the components in a window. Instead, CTRL-TAB is absorbed by the browser.
+
+
+LookAndFeel and UI Classes
+--------------------------
+
+SwingJS implements the native browser look and feel as swingjs.plaf.HTML5LookAndFeel.
+There are small differences between all look and feels -- MacOS, Windows, SwingJS.
+
+Expert developers know how to coerce changes in the UI by subclassing the UI for a
+component. This probably will not work in SwingJS.
+
+Note that LookAndFeel in Java usually determines canvas size in a Frame because
+different operating systems (Mac OS vs Windows vs HTML5) will have
+different edge sizes on their frames. If you want to ensure a component size,
+use getContentPane().setPreferredSize().
+
+
+System.exit(0) does not stop all processes
+------------------------------------------
+
+Although System.ext(int) has been implemented in JavaScript, it just closes the
+frames, stops all pending javax.swing.Timer objects in the queue, and runs any
+threads added using Runtime.getRuntime().addShutdownHook(Thread).
+It may not stop all "threads." So don't rely on that.
+Applications are responsible for shutting down prior to executing System.exit(0).
+
+
+myClass.getField not implemented
+--------------------------------
+
+java.lang.reflect.Field is implemented minimally. It is not
+certain that Field.getDeclaringClass() will work. If you just want a
+value of a field, you can do this:
+
+/**
+ *@j2sNative
+ *
+ * return myClass[name]
+ */
+
+But that is not a java.lang.reflection.Field object.
+
+
+"window" and other reserved JavaScript names
+--------------------------------------------
+
+No reserved top-level JavaScript name is allowed for a package name. So, for example,
+one must rename packages such as "window" or "document" to names such as "win" or "doc".
+
+reserved field and method names
+-------------------------------
+
+In order to minimize the chance of added SwingJS field and method names colliding with ones
+developers might use in subclassing Java classes, we have added U+79D8 (first character of Mandarin
+"secret") to the characters already disrecommended by Java documentation ("$" and "_"). The only problem
+would be if you use that character followed by certain English words in certain classes. For example
+\u79D8canvas for JComponents (in java.awt.JSComponent) and \u79D8byte (in java.io.File).
+
+qualified field and method names
+--------------------------------
+
+Method names in SwingJS are fully qualified, meaning two methods with the same Java name but different
+parameters, such as write(int) and write(double), must not have the same name in JavaScript. (In this
+case, we will have write$I and write$D.) However, in certain cases it may be desirable to leave the
+method names unqualified. In particular, when an interface actually represents a JavaScript object,
+the transpiler can leave a method name unqualified. The default situation for this is a class name
+includes ".api.js" (case-sensitive). This means that any method in any class in a package js within
+a package api, or any private interface js that has an outer interface api, will have all-unqualified
+methods. An example of this is swingjs.plaf.JSComboPopupList, which needs to communicate with a jQuery
+object directly using the following interface:
+
+ private interface api {
+
+ interface js extends JQueryObject {
+
+ abstract js j2sCB(Object options);
+
+ abstract Object[] j2sCB(String method);
+
+ abstract Object[] j2sCB(String method, Object o);
+
+ abstract Object[] j2sCB(String method, int i);
+
+ abstract int j2sCB(String OPTION, String name);
+
+ }
+ }
+
+Notice that all these variants of j2sCB() will call the same method in JavaScript by design.
+
+
+missing Math methods
+--------------------
+
+java.lang.Math is worked out, but some methods are missing, either because they
+involve long integer value that are inaccessible in JavaScript, or because I just
+didn't implement them. This is a result of continued Java development.
+It is easy enough to add these methods if you have the source. They go into j2sClazz.js,
+which is combined with other initial libraries into swingjs2.js by build_site.xml
+
+
+Component.getGraphics(), Graphics.dispose()
+-------------------------------------------
+
+Use of component.getGraphics() is discouraged in Java and in SwingJS.
+Specifically in SwingJS, any call to component.getGraphics() or
+BufferedImage.createGraphics() or Graphics.create(...) should be matched with graphics.dispose(),
+particularly when it is called outside the context of a paint(Graphics)
+call from the system.
+
+If you see your graphics scrolling down the page with each repaint,
+look for where you have used Component.getGraphics() and not Graphics.dispose().
+For example, this will definitely NOT work in SwingJS:
+
+ this.paint(getGraphics())
+
+and really should not work in Java, either, as it is technically a resource memory leak.
+
+Instead, if you really do not want to use repaint(), use this:
+
+ Graphics g = getGraphics();
+ paint(g);
+ g.dispose();
+
+
+
+Graphics.setClip()
+------------------
+
+The HTML5 canvas.clip() method is permanent. You can only reset the clip using
+save/restore. This is different from Java, where you can temporarily change it using
+
+ Shape oldClip = Graphics.getClip();
+ Graphics.setClip(newClip);
+ ...
+ Graphics.setClip(oldClip);
+
+If you need to do something like this, you must schedule the paints
+to not have overlapping clip needs.
+
+
+MAJOR ISSUES--for Bob and Udo within SwingJS
+============================================
+
+fonts
+-----
+
+Fonts and FontMetrics will all be handled in JavaScript. Font matching will
+not be exact, and composite (drawn) fonts will not be supported.
+
+SwingJS handles calls such as font.getFontMetrics(g).stringWidth("xxx") by
+creating a <div> containing that text, placing it in an obscure location on
+the page, and reading div.getBoundingClientRect(). This is a VERY precise
+value, but can be a pixel or two off from what Java reports for the same font.
+
+
+OS-dependent classes
+--------------------
+
+Static classes such as:
+
+ java.awt.Toolkit
+ java.awt.GraphicsEnvironment
+
+
+which are created using Class.forName are implemented using classes in the swingjs package.
+
+AWTAccessor is not implemented.
+
+
+AWT component peers and component "ui" user interfaces
+------------------------------------------------------
+
+ComponentPeer is a class that represents a native AWT component.
+Components with such peers are called "heavy-weight" components.
+They are expected to do the dirty work of graphics drawing.
+
+Java Swing implements peers only for JApplet, JDialog, JFrame, and JWindow.
+References to such objects have been removed, but clearly there must be
+some connection to similar DOM objects, even for "light-weight" components.
+
+
+
+MAJOR ISSUES--to be resolved by implementers
+============================================
+
+fonts
+-----
+
+Glyph/composite/outline fonts are not supported.
+
+
+
+threads
+-------
+
+Thread locking and synchronization are not relevant to JavaScript.
+Thus, anything requiring "notify.." or "waitFor.." could be a serious issue.
+
+All threading must be "faked" in JavaScript. Specifically not available is:
+
+ Thread.sleep()
+
+javax.swing.AbstractButton#doClick(pressTime) will not work, as it requires Thread.sleep();
+
+However, java.lang.Thread itself is implemented and used extensively.
+
+Methods thread.start() and thread.run() both work fine.
+
+For simple applications that use Thread.sleep() just to have a delay, as in a frame rate, for
+example, one can use javax.swing.Timer instead. That is fully implemented.
+
+Likewise, java.util.Timer can be replaced with no loss of performance with javax.Swing.Timer.
+Note that java.util.TimerTask is implemented, but it can also be replaced by an implementation of Runnable.
+
+task = new TimerTask(){....};
+t = new java.util.Timer();
+t.schedule(task, 0, 1);
+
+becomes
+
+task = new TimerTask(){....}; // or task = new Runnable() {...}
+t = new javax.swing.Timer(1, new ActionListener() {
+ @Override
+ public void actionPerformed(ActionEvent e) {
+ task.run();
+ }
+};
+t.setInitialDelay(0); // not particularly necessary
+t.start();
+
+In addition, SwingJS provides swingjs.JSThread, which can be subclassed
+if desired. This class allows simple
+
+ while(!interrupted()){
+ wait()
+ ...
+ }
+
+action through an asynchronous function run1(mode). For example:
+
+ protected void run1(int mode) {
+ try {
+ while (true)
+ switch (mode) {
+ case INIT:
+ // once-through stuff here
+ mode = LOOP;
+ break;
+ case LOOP:
+ if (!doDispatch || isInterrupted()) {
+ mode = DONE;
+ } else {
+ Runnable r = new Runnable() {
+ public void run() {
+ // put the loop code here
+ }
+ };
+ dispatchAndReturn(r);
+ if (isJS)
+ return;
+ }
+ break;
+ // add more cases as needed
+ case DONE:
+ // finish up here
+ if (isInterrupted())
+ return;
+ // or here
+ break;
+ }
+ } finally {
+ // stuff here to be executed after each loop in JS or at the end in Java
+ }
+ }
+
+image loading
+-------------
+- All image loading in SwingJS is synchronous. A MediaTracker call will immediately return "complete".
+ However, it still may take one system clock tick to fully load images. Thus, it is recommended that
+ images be preloaded in the static block of the applet if it is necessary that they be available in init().
+ This is only an issue if you are trying to access the pixel buffer of the image in JavaScript.
+
+- Applet.getImage(path, name) will return null if the image does not exist.
+
+- BufferedImage: only "support" imageType RGB and ARGB
+
+ -BH: This is a temporary edit, just to get us started. Certainly GRAY will be needed
+
+
+BigInteger and BigDecimal
+-------------------------
+
+java.math.BigInteger is fully supported; java.math.BigDecimal is roughed
+in and not fully tested (07/2019).
+
+Both classes present significant issues for JavaScript, as they are based in
+Java's 64-bit long for all their operations. Here is the JavaDoc note I added
+to BigInteger:
+
+ * SwingJS note: Because of the limitations of JavaScript with regard
+ * to long-integer bit storage as a double, this implementation drops
+ * the integer storage bit length to 24, giving 48 for long and leaving
+ * the last 16 bits clear for the exponent of the double number. This should
+ * not affect performance significantly. It does increase the storage
+ * size by about 33%. By bringing an "int" to 3 bytes, we can easily construct
+ * and use byte[] data intended for the original BitSet.
+
+"Easily" may be a bit strong there. This was a serious challenge.
+
+BigDecimal seems to run normally, but in order to do that, my hack involves
+reducing the size of an integer that is allowed to be stored as such and not
+in byte[] as a BigInteger. I'm sure there is a performance hit, but it does work.
+
+no format internationalization
+------------------------------
+
+For now, just en for number and date formatters
+
+no winding rules
+----------------
+
+ When filling a graphic, only nonzero winding rule is implemented in HTML5 Canvas2D.
+
+
+
+text-related field implementation
+---------------------------------
+
+Text fields are:
+
+JTextField (JavaScript <input type="text">)
+JTextArea (JavaScript <textarea>)
+JTextPane (JavaScript <div>)
+JEditorPane (JavaScript <div>)
+
+For the initial implementation, we don't implement infinite undo/redo, and the abstract
+document model is much less elaborate. Only PlainDocument (in the form of JSPlainDocument)
+is implemented. The Document returned by JTextField.getDocument() is a javax.swing.text.Document.
+
+All scrolling is handled by HTML5. javax.swing.AutoScroller is not implemented.
+public static methods .stop, .isRunning, .processMouseDragged require true Java threading
+and so are not implmented. javax.swing.text.View and its subclasses are not implemented.
+
+The JS document model does not allow two text fields to address the same underlying document.
+
+JavaScript is slightly different from Java in that the field value is changed asynchronously after
+the keypressed event, so Java actions that are keyed to KEY_PRESSED may not pick up the new
+key value even after SwingUtilities.invokeLater() is called. Thus, key pressed actions may need
+to be recorded after a key released event instead.
+
+Formatter/Regex limitations
+---------------------------
+
+Some browsers cannot process Regex "look-behind" process such as (?<=\W)
+java.util.regex.Matcher and Pattern use JavaScript's RegExp object rather than
+the native Java object. These are not identical. Only flags /igm are supported.
+Matcher.start(groupID) is not supported.
+
+java.util.Formatter will function correctly for all standard %... patterns.
+
+integer 1/0 == Infinity
+-----------------------
+
+1/0 in Java throws "java.lang.ArithmeticException: / by zero", but in JavaScript is just Infinity.
+
+
+
+Summary
+-------
+
+These are all the known limitations of SwingJS. We have not found any of these limitations
+to be show-stoppers. The primary issue for newcomers to SwingJS is having the source code.
+You must check that source code for all your library jar files is available or, if you
+choose, you will need to decompile those classes. We have used decompilation on some projects,
+and it works just fine. So, technically, all we really need are JAR/class files. But the
+source is by far superior. It's generally prettier, and it has the license information that
+may or may not be present with the JAR or class files. Use class files at your own risk.
+
+Bob Hanson
+2019.08.16
+
+
+Additional Issues
+-----------------
+
+Annotation is working for classes, methods, and fields (12/22/19). Method reflection, however,
+is limited. Interfaces do not expose their methods, as the transpiler does not actually transpile
+the interfaces themselves. And method reflection only includes annotated methods.
+
+java.util.concurrent is not fully elaborated. This package is rewritten to not actually use the
+memory handling capabilities of concurrency, which JavaScript does not have access to.
+
+System.getProperties() just returns a minimal set of properties.
+
+
-20191202082005
+20201219175119
--- /dev/null
+Notes
+=====
+
+---IMPORTANT CHARACTER SET NOTE---
+
+It is critical that all development work in Java2Script
+be done in UTF-8. This means:
+
+- making sure your Eclipse project is set up for UTF-8 (not the Eclipse default?)
+- making sure your server can serve up UTF-8 by default for any browser-loaded files
+- making sure you don't edit a Java2Script class file or one of the site .js files
+ using a non-UTF-8 editor. It may replace non-Latin characters with "?" or garbage.
+- making sure that your web pages are delivered with proper headings indicating HTML5 and UTF-8
+
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="utf-8">
+
+Note that the DOCTYPE tag is critical for some browsers to switch into HTML5 mode. (MSIE?)
+
+
+
+
+In particular, the Mandarin character 秘 (mi; "secret") is used extensively throughout
+the SwingJS class files to distinguish j2s-specific fields and methods that must not
+ever be shadowed or overridden by subclasses. For example, we see in java.lang.Thread.java:
+
+ public static JSThread 秘thisThread;
+
+----------------------------------
+
+
+updated 3/21/2020 -- adds note about HashMap, Hashtable, and HashSet iterator ordering
+updated 3/20/2020 -- adds note about interning, new String("xxx"), and "xxx"
+updated 2/26/2020 -- adds Graphics.setClip issue
+updated 12/22/19 -- additional issues
+updated 11/03/19 -- adds information about File.exists() and points to src/javajs/async
+updated 10/26/19 -- adds information about File.createTempFile()
+updated 8/16/19 -- minor typos and added summary paragraph
+updated 7/19/19 -- clarification that AWT and Swing classes are supported directly
+updated 5/13/19 -- Mandarin U+79D8 reserved character; Missing Math methods; int and long
+updated 5/10/19 -- adds a section on static issues in multi-(duplicate)-applet pages
+updated 1/4/19 -- nio
+updated 9/15/18 -- adds integer 1/0 == Infinity
+updated 7/24/18 -- most classes replaced with https://github.com/frohoff/jdk8u-jdk
+updated 6/5/17 -- reserved package name "window"
+updated 3/11/17 -- myClass.getField
+updated 3/7/17 -- overloading of JSplitPane.setDividerLocation
+updated 3/2/17 -- more indication of classes not implemented (KeyListener)
+
+=============================================================================
+SwingJS and OpenJDK 8+
+=============================================================================
+
+SwingJS implements a wide range of the Java language in JavaScript. The base
+version for this implementation is OpenJDK8. some classes are implemented using
+older source code, and there are some missing methods. For the most part, this is
+no real problem. You can add or modify any java class just be adding it as source
+in your project. Or (preferably) you can contact me, and I can get it into the
+distribution. Or (even more preferably) you can do that via a patch submission.
+
+=================
+DESIGN PHILOSOPHY
+=================
+
+The java2script/SwingJS design goal is to recreate a recognizable, easily debuggable
+equivalent in JavaScript for as much of Java as practical. This means, for example,
+that one can call in JavaScript
+
+ new java.util.Hashtable()
+
+and for all practical purposes it will appear that Java is running.
+
+
+Method and Field Disambiguation
+-------------------------------
+
+SwingJS has no problem with the overloading of methods, for example:
+
+ public void print(int b);
+ public void print(float b);
+
+JavaScript does not allow overloading of methods, and the common practice in
+Java of naming a field the same as a method -- isAllowed and isAllowed() -- is
+not possible in JavaScript. As a result, SwingJS implements "fully-qualified"
+method names using "$" parameter type separation. Thus, these methods in SwingJS
+will be referred to as print$I and print$F. The rules for this encoding are
+relatively simple:
+
+1. The seven primitive types in Java are encoded $I (int), $L (long), $F (float),
+$D (double), $B (byte) $Z (boolean), and $H (short).
+
+2. String and Object are encoded as $S and $O, respectively.
+
+3. "java_lang_" is dropped for all other classes in the java.lang package (as in Java).
+ For example: $StringBuffer, not $java_lang_StringBuffer
+
+4. All other classes are encoded as
+
+ "$" + Class.getName().replace(".","_")
+
+For example, in Java we see:
+
+ public void equals(Object o) {...}
+
+Whereas in SwingJS we have:
+
+ Clazz.newMeth(C$, 'equals$O', function (o) {...}
+
+And
+
+ this.getContentPane().add(bar, "North");
+
+becomes
+
+ this.getContentPane$().add$java_awt_Component$O(bar, "North");
+
+5. Arrays are indicated with appended "A" for each level. So
+
+ setDataVector(Object[][] dataVector, Object[] columnIdentifiers)
+
+becomes
+
+ setDataVector$OAA$OA(dataVector, columnIdentifiers)
+
+(It is recognized that this design does introduce a bit of ambiguity, in that
+ in principal there could be user class named XA and X in the same package,
+ and methods a(X[]) and a(XA) in the same class that cannot be distinguished.
+ The benefit of this simple system, however, triumphed over the unlikelyhood
+ of that scenario.) The transpiler could be set to flag this possibility.
+
+6. Constructors are prepended with "c$". So
+
+ public JLabel(String text) {...}
+
+becomes:
+
+ Clazz.newMeth(C$, 'c$$S', function (text) {...});
+
+Field disambiguation involves prepending. In Java, a class and its subclass
+can both have the same field name, such as
+
+ boolean visible;
+
+When this happens, it is called "shadowing", and though not recommended, Java allows
+it. The Java2Script transpiler will prepend such shadowing fields with "$" so that the
+subclass instance has both "visible" (for use in its methods inherited from its
+superclass) and "$visible" (for its own methods). Thus, we might see in Java:
+
+ this.visible = super.visible;
+
+while in SwingJS we will see:
+
+ this.$visible=this.visible;
+
+since JavaScript does not have the "super" keyword.
+
+
+
+Parameterless methods such as toString() are appended with "$" to become toString$().
+The one exception to this rule is private methods, which are saved in (truly) private
+array in the class (and are not accessible by reflection). Private parameterless
+methods retain their simple Java name, since they cannot conflict with field names.
+
+This renaming of methods has a few consequences, which are discussed more fully below.
+See particularly the section on "qualified field and method names", where it is described
+how you can use packages or classes or interfaces with ".api.js" in them to represent JavaScript
+objects for which all method names are to be left unqualified. Note that it is not
+possible to cherry-pick methods to be unqualified; only full packages, classes or
+interfaces can hold this status.
+
+The swingjs.api.js package in particular contains a number of useful interfaces that
+you can import into your project for JavaScript-specific capabilities.
+
+
+Applet vs. Application
+----------------------
+
+One of the very cool aspects of SwingJS is that it doesn't particularly matter if a browser-based
+Java app is an "applet" or an "application". We don't need JNLP (Java Network Launch Protocol)
+because now we can just start up any Java application in a browser just as easily as any applet.
+The associative array that passes information to the SwingJS applet (information that formerly
+might have been part of the APPLET tag, such as width, height, and codebase, always referred to
+in our writing as "the Info array") allows the option to specify the JApplet/Applet "code"
+class or the application "main" class. Either one will run just fine.
+
+
+Performance
+-----------
+
+Obviously, there are limitations. One is performance, but we have seen reproducible
+performance at 1/6 - 1/3 the speed of Java. Achieving this performance may require
+some refactoring of the Java to make it more efficient in both Java and JavaScript.
+"for" loops need to be more carefully crafted; use of "new" and "instanceof" need to be
+minimized in critical areas. Note that method overloading -- that is, the same method name
+with different parameters, such as read(int) and read(byte) -- is no longer any problem.
+
+
+Threads
+-------
+
+Although there is only a single thread in JavaScript, meaning Thread.wait(), Thread.sleep(int) and
+Thread.notify() cannot be reproduced, we have found that this is not a serious limitation.
+For example, javax.swing.Timer() works perfectly in JavaScript. All it means is that threads
+that use sleep(int) or notify() must be refactored to allow Timer-like callbacks. That is,
+they must allow full exit and re-entry of Thread.run(), not the typical while/sleep motif.
+
+The key is to create a state-based run() that can be exited and re-entered in JavaScript.
+
+
+Static fields
+-------------
+
+Final static primitive "constant" fields (String, boolean, int, etc.) such as
+
+static final int TEST = 3;
+static final String MY_STRING = "my " + "string";
+
+are converted to their primitive form automatically by the Eclipse Java compiler
+and do not appear in the JavaScript by their names.
+
+Other static fields are properties of their class and can be used as expected.
+
+Note, however, that SwingJS runs all "Java" code on a page in a common "jvm"
+(like older versions of Java). So, like the older Java schema, the JavaScript
+equivalents of both applets and applications will share all of their static
+fields and methods. This includes java.lang.System.
+
+Basically, SwingJS implementations of Java run in a browser page-based sandbox
+instead of an applet-specific one.
+
+In general, this is no problem. But if we are to implement pages with
+multiple applets present, we must be sure to only have static references
+that are "final" or specifically meant to be shared in a JavaScript
+environment only (since they will not be shared in Java).
+
+A simple solution, if static non-constant references are needed, is to attach the
+field to Thread.currentThread.threadGroup(), which is an applet-specific reference.
+Be sure, if you do this, that you use explicit setters and getters:
+
+For example,
+
+private static String myvar;
+
+...
+
+public void setMyVar(String x) {
+ ThreadGroup g = Thread.currentThread().threadGroup();
+ /**
+ * @j2sNative g._myvar = x;
+ *
+ */
+ {
+ myvar = x;
+ }
+}
+
+public String getMyVar() {
+ ThreadGroup g = Thread.currentThread().threadGroup();
+ /**
+ * @j2sNative return g._myvar || null;
+ *
+ */
+ {
+ return myvar;
+ }
+}
+
+ in Java will get and set x the same in JavaScript and in Java.
+
+
+A convenient way to do this in general is to supply a singleton class with
+explicitly private-only constructors and then refer to it in Java and in JavaScript
+instead of using static field, referring to myclass.getIntance().xxx instead of
+myclass.xxx in Java (and JavaScript).
+
+This was done extensively in the Jalview project. See jalview.bin.Instance.
+
+
+Helper Packages -- swingjs/ and javajs/
+---------------------------------------
+
+The SwingJS library is the swingjs/ package. There are interfaces that may be of assistance
+in swingjs/api, but other than that, it is not recommended that developers access classes in
+this package. The "public" nature of their methods is really an internal necessity.
+
+In addition to swingjs/, though, there are several useful classes in the javajs/ package
+that could be very useful. This package is a stand-alone package that can be
+cloned in any Java project that also would be great to have in any JavaScript project
+-- SwingJS-related or not. Functionality ranges from reading and writing various file
+formats, including PDF, BMP, PNG, GIF, JPG, JSON, ZIP, and CompoundDocument formats.
+
+A variety of highly efficient three- and four-dimensional point, vector, matrix, and
+quaternion classes are included, as they were developed for JSmol and inherited from that
+project.
+
+Of particular interest should be javajs/async/, which includes
+
+javajs.async.Async
+javajs.async.AsyncColorChooser
+javajs.async.AsyncDialog
+javajs.async.AsyncFileChooser
+
+See javajs.async.Async JavaDoc comments for a full description of
+these useful classes.
+
+
+Modal Dialogs
+-------------
+
+Although true modal dialogs are not possible with only one thread, a functional equivalent --
+asynchronous modal dialogs -- is relatively easy to set up. All the JOptionPane dialogs will
+return PropertyChangeEvents to signal that they have been disposed of and containing the results.
+See below and classes in the javajs.async package.
+
+
+Native calls
+------------
+
+Native calls in Java are calls to operating system methods that are not in Java. JavaScript
+has no access to these, of course, and they must all be replaced by JavaScript equivalents.
+Fortunately, they are not common, and those that are present in Java (for example, in calculating
+checksums in ZIP file creation) are at a low enough level that most developers do not utilize them
+or do not even have access to them. All native calls in Java classes have been replaced by
+Java equivalents.
+
+
+Swing GUI Peers and UIClasses
+-----------------------------
+
+One of the biggest adaptations introduced in SwingJS is in the area of the graphical
+user interface. The issue here is complex but workable. In Java there are two background
+concepts -- the Component "peer" (one per "heavy-weight" component, such as a Frame) and the
+component "uiClass" (one per component, such as JButton or JTextField).
+
+Peers are native objects of the operating system. These are the virtual buttons and text areas
+that the user is interacting with at a very base level. Their events are being passed on to
+Java or the browser by the operating system. UI classes provide a consistent "look and feel"
+for these native objects, rendering them onto the native window canvas and handling all
+user-generated events. They paint the borders, the backgrounds, the highlights, of every
+control you see in Java. There is one-to-one correspondence of Swing classes and UI classes.
+Setting the Look and Feel for a project amounts to selecting the directory from which to draw
+these UI classes. The UI classes can be found in the javax.swing.plaf ("platform look and feel")
+package.
+
+Early on in the development of SwingJS, we decided not to fully reproduce the painfully detailed
+bit-by-bit painting of controls as is done in Java. Instead, we felt it was wiser to utilize the standard
+HTML5 UI capabilities as much as possible, using DIV, and INPUT especially, with extensive use
+of CSS and sometimes jQuery (menus, and sliders, for example). Thus, we have created a new
+set of UIs -- the "HTML5 Look and Feel". These classes can be found in swingjs.plaf. Besides being
+more adaptable, this approach allows far more versatility to SwingJS developers, allowing them
+to modify the GUI to suit their needs if desired.
+
+In SwingJS, since we have no access to native peers except through the browser DOM,
+it seemed logical to merge the peer and UI idea. So instead of having one peer per heavy-weight control and
+one UI class instance for each control type, we just have one UI class instance per control, and
+that UI class instance is what is being referred to when a "peer" is notified.
+
+In some ways this is a throw back to when all of Swing's components were subclasses of
+specific AWT components such as Button and List. These "heavy-weight components" all had their
+own individual native peers and thus automatically took on the look and feel provided by the OS.
+Later Swing versions implemented full look and feel for all peers, leaving only JDialog, JFrame,
+and a few other classes to have native peers. But in SwingJS we have again a 1:1 map of component
+and UI class/peer instance.
+
+The origin of most issues (read "bugs") in relation to the GUI will probably be found in the
+swingjs.plaf JSxxxxUI.java code.
+
+
+Swing-only Components -- no longer an issue
+-------------------------------------------
+
+Swing was introduced into Java well after the Java Abstract Window Toolkit (AWT) was well
+established. As such, its designers chose to allow AWT controls such as Button and List to be used
+alongside their Swing counterparts JButton and JList. Reading the code, it is clear that this
+design choice posed a huge headache for Swing class developers.
+
+For SwingJS, we decided from the beginning NOT to allow this mixed-mode programming and
+instead to require that all components be Swing components.
+
+However, this is no longer an issue. All AWT components in SwingJS are now subclasses of
+javax.swing.JComponent. So far, we have found no problem with this.
+
+
+The a2s Adapter Package
+-----------------------
+
+Originally, we thought that we would restrict ourselves to JApplets only. That is, only
+Swing-based applets. But as we worked, we discovered that there are a lot of great
+applets out there that are pre-Swing pure-AWT java.applet.Applet applets. Our problem was
+that we also wanted it to be possible to quickly adapt these applets to JavaScript as well.
+
+The solution turned out to be simple: Write a package (a2s) that recreates the interface for
+non-Swing components as subclasses of Swing components. Thus, a2s.Button subclasses javax.swing.JButton
+but also accepts all of the methods of java.awt.Button. This works amazingly well, with a few
+special adaptations to the core javax.swing to be "AWT-aware." All AWT components now subclass
+a2s components, which in turn subclass JComponents. So no changes in code are necessary. We have
+successfully transpiled over 500 applets using this strategy. (Kind of surprising, actually, that
+the original Java developers did not see that option. But we have a hindsight advantage here.)
+
+
+Working with Files
+==================
+
+Simple String file names are not optimal for passing information about
+read files within SwingJS applications.
+
+All work with files should either use Path or File objects exclusively.
+These objects, after a file is read or checked for existence, will already
+contain the file byte[] data. Doing something like this:
+
+File f = File("./test.dat");
+boolean isOK = f.exists();
+
+will load f with its byte[] data, if the file exists.
+
+But if after that, we use:
+
+File f2 = new File(f.getAbsolutePath());
+
+f2 will not contain that data. Such copying should be done as:
+
+File f2 = new File(f);
+
+in which case, the byte[] data will be transferred.
+
+
+SwingJS uses the following criteria to determine if File.exists() returns true:
+
+(1) if this File object has been used directly to read data, or
+(2) if reading data using this File object is successful.
+
+Note that you cannot check to see if a file exists before input or if it
+was actually written or if it already exists prior to writing in SwingJS.
+
+Thus, you should check each use of file.exists() carefully, and if necessary, provide a J2sNative
+block that gives an appropriate "OK" message, for example:
+
+(/** @j2sNative 1 ? false : */ outputfile.exits())
+
+or
+
+(/** @j2sNative 1 ? true : */ inputfile.exits())
+
+Temporary files can be created in SwingJS. SwingJS will maintain a pseudo-filesystem for files
+created with File.createTempFile(). This is useful in that closure of writing to a temporary file
+does not generate a pseudo-download to the user's machine.
+
+
+UNIMPLEMENTED CLASSES BY DESIGN
+===============================
+
+The SwingJS implementation of the following classes are present
+in a way that gracefully bypasses their functionality:
+
+accessibility
+security
+serialization
+
+
+
+TODO LIST FOR UNIMPLEMENTED CLASSES
+===================================
+
+JEditorPane (minimal implementation) - DONE 12/2018; some issues still
+JSplitPane - DONE 8/2018
+JTabbedPane - DONE 10/2018
+JTree - done 12/2019
+
+
+MINOR ISSUES--required some rewriting/refactoring by Bob and Udo
+================================================================
+
+Thread.currentThread() == dispatchThread
+
+
+MINOR ISSUES--requiring some rewriting/refactoring outside of SwingJS
+=====================================================================
+
+See below for a full discussion.
+
+HashMap, Hashtable, and HashSet iterator ordering
+interning, new String("xxx") vs "xxx"
+Names with "$" and "_"
+positive integers do not add to give negative numbers
+ArrayIndexOutOfBounds
+java.awt.Color
+native methods
+javax.swing.JFileDialog
+key focus
+LookAndFeel and UI Classes
+System.exit(0) does not stop all processes
+list cell renderers must be JComponents
+myClass.getField not implemented
+"window" and other reserved JavaScript names
+reserved field and method names
+qualified field and method names
+missing Math methods
+Component.getGraphics(), Graphics.dispose()
+Graphics.setClip()
+
+MAJOR ISSUES--for Bob and Udo within SwingJS
+============================================
+
+fonts
+OS-dependent classes
+AWT component peers
+some aspects of reflection
+
+MAJOR ISSUES--to be resolved by implementers
+============================================
+
+fonts
+threads
+modal dialogs
+image loading
+BigDecimal not fully implemented
+no format internationalization
+no winding rules
+text-related field implementation
+Formatter/Regex limitations
+integer 1/0 == Infinity
+
+========================================================================
+
+DISCUSS
+=======
+
+Table row/col sorter needs checking after removal of java.text.Collator references
+
+I had to move all of SunHints class to RenderingHints, or the
+two classes could not be loaded. Shouldn't be a problem, I think. The sun classes are
+not accessible to developers in Java anyway, since they are generally package private.
+
+==========================================================================
+
+//////////////////////////////////////////////////////////////////////////////
+
+UNIMPLEMENTED CLASSES
+=====================
+
+accessibility
+-------------
+
+All Accessibility handling has been commented out to save the download footprint.
+This removes the need for sun.misc.SharedSecrets as well.
+Nothing says we could not implement accessibility. We just didn't.
+
+
+security
+--------
+
+All JavaScript security is handled by the browser natively.
+Thus, Java security checking is no longer necessary, and
+java.security.AccessController has been simplified to work without
+native security checking.
+
+Note that private methods in a class are REALLY private.
+
+
+serialization
+-------------
+
+All serialization has been removed. It was never very useful for Swing anyway,
+because one needs exactly the same Java version to save and restore serialized objects.
+
+
+keyboard accelerators and mnemonics
+-----------------------------------
+
+This work was completed in the spring of 2019. Note that in a browser, some
+key strokes, particularly CTRL-keys, are not available. Bummer.
+
+
+MINOR ISSUES--required some rewriting/refactoring by Bob and Udo
+================================================================
+
+
+Thread.currentThread() == dispatchThread
+----------------------------------------
+
+changed to JSToolkit.isDispatchThread()
+
+
+MINOR ISSUES--requiring some rewriting/refactoring outside of SwingJS
+=====================================================================
+
+HashMap, Hashtable, and HashSet iterator ordering
+-------------------------------------------------
+
+In Java, iterators for HashMap, Hashtable, and HashSet do not guarantee any particular order.
+From the HashMap documentation for Java 8:
+
+ This class makes no guarantees as to the order of the map; in particular, it does not
+ guarantee that the order will remain constant over time.
+
+Likewise, for HashSet (because it is simply a convenience method for HashMap<Object,PRESENT>:
+
+ [HashSet] makes no guarantees as to the iteration order of the set.
+
+JavaScript's Map object is different. It is basically a LinkedHashMap, so it guarantees iteration
+in order of object addition.
+
+Starting with java2script 3.2.9.v1, these classes use the JavaScript Map object rather than hash codes
+whenever all keys are strictly of JavaScript typeof "string". If any key is introduced that is not a string, the
+implementation falls back to using hash codes, the same as Java.
+
+Note strings created using new String("xxxx") are NOT typeof "string"; they are typeof "object".
+
+The result is significantly faster performance (3-12 x faster) than originally, and up to 3 x faster
+performance in JavaScript than in Java itself. Right. Faster than Java.
+
+The JavaScript Map implementation is implemented UNLESS the constructor used is the one that
+specifies both initial capacity and load factor in their constructor. Thus,
+
+new Hashtable()
+new HashMap()
+new HashMap(16)
+new HashSet()
+
+all use the JavaScript Map. But
+
+new Hashtable(11, 0.75f)
+new HashMap(16, 0.75f)
+new HashSet(16, 0.75f)
+
+do not.
+
+This design allows for opting out of the JavaScript Map use in order to retain the exact behavior of
+iterators in JavaScript as in Java.
+
+
+interning, new String("xxx") vs "xxx"
+-------------------------------------
+
+Note that the following are true in JavaScript:
+
+typeof new String("xxxx") == "object"
+typeof "xxxx" == "string"
+var s = "x";typeof ("xxx" + s) == "string"
+
+There is no equivalence to this behavior in Java, where a String is a String is a String.
+
+Be aware that SwingJS does not always create a JavaScript String object using JavaScript's
+new String(...) constructor. It only does this for Java new String("xxxx") or new String(new String()).
+
+In all other cases, new String(...) (in Java) results in a simple "xxxx" string in JavaScript.
+That is, it will be JavaScript typeof "string", not typeof "object".
+
+The reason for this design is that several classes in the Java core use toString()
+methods that return new String(), and those classes that do that would cause a JavaScript error
+if implicitly stringified if new String() returned a JavaScript String object.
+
+This is fine in JavaScript
+
+test1 = function() { return { toString:function(){ return "OK" } } }
+"testing" + new test1()
+>> "testingOK"
+
+But for whatever reason in JavaScript:
+
+test2 = function() { return { toString:function(){ return new String("OK") } } }
+"testing" + new test2()
+>> Uncaught TypeError: Cannot convert object to primitive value
+
+The lesson here is never to use
+
+ return new String("...");
+
+in a Java toString() method. In Java it will be fine; in JavaScript it will also be fine as long as
+that method is never called in JavaScript implicitly in the context of string concatenation.
+
+A note about interning. Consider the following six Java constructions, where we have a == "x";
+
+"xxx"
+"xx" + "x"
+new String("xxx").intern()
+
+new String("xxx")
+"xx" + a.toString()
+"xx" + a
+
+All six of these will return java.lang.String for .getClass().getName().
+However, the first three are String literals, while the last three are String objects.
+Thus:
+ "xxx" == "xxx"
+ "xxx" == "xx" + "x"
+ "xxx" == new String("xxx").intern()
+
+but none of the other three are equivalent to "xxx" or each other:
+
+ "xxx" != new String("xxx")
+ "xxx" != "xx" + a.toString()
+ "xxx" != "xx" + a
+ new String("xxx") != new String("xxx")
+ "xx" + a != new String("xxx")
+
+etc.
+
+As in Java, in SwingJS, all of the following Java assertions pass as true:
+
+ assert("xxx" == "xx" + "x");
+ assert("xxx" == ("xx" + a).intern());
+ assert("xxx" === new String("xxx").intern());
+
+and both of these do as well:
+
+ assert(new String("xxx") != "xxx");
+ assert(new String("xxx") != new String("xxx"));
+
+But the following two fail to assert true:
+
+ assert("xxx" != "xx" + a);
+ assert("xxx" != "xx" + a.toString());
+
+because in JavaScript, both of these right-side expressions evaluate to a simple "interned" string.
+
+In Java, however, these assertions are true because Java implicitly "boxes" String
+concatentaion as a String object, not a literal.
+
+Most of us know not to generally use == with Strings unless they are explicitly interned.
+Where this problem may arise, though, is in IdentityHashMap, which compares objects using
+System.identityHashCode(), which is not the same for different objects or their string literal equivalents.
+
+My recommendation, if you need to use IdentityHashMap with strings is to always use an explicit String.intern()
+for any keys -- unless you really want to keep every string as separate keys even if they are the same sequence,
+in which case, use new String(). This will work in Java and in JavaScript.
+
+Be aware when working with strings that come from SwingJS and are being used by other JavaScript modules
+that those that are String objects will return "object" for the JavaScript typeof operator, not "string".
+
+The easy way to ensure this is no problem is to concatenate strings with "" to force immediate interning:
+
+ var x = aJavaObject.getString() + "";
+
+unless you are certain that the string is being returned is a raw JavaScript string.
+
+Names with "$" and "_"
+----------------------
+
+For the most part, this should be no problem.
+
+Note that the use of $ and _ in Java field names has always been discouraged:
+[https://docs.oracle.com/javase/tutorial/java/nutsandbolts/variables.html]
+
+ You may find some situations where auto-generated names will contain the dollar sign,
+ but your variable names should always avoid using it. A similar convention
+ exists for the underscore character; while it's technically legal to begin your
+ variable's name with "_", this practice is discouraged.
+
+Some impacts of transpiling method names with full qualification:
+
+1) SwingJS will introduce fields that start with $ or _. These will not conflict
+ if the above convention is followed.
+
+2) Fields that have the same Java name as a method are not an issue.
+
+3) Fields that have a Java name with $ that matches a transpiled method name,
+ such as toString$, will need to be refactored in Java to not have that name collision.
+
+4) Fields in a subclass that have the same name as private fields in a superclass
+ represent a name collision, because the superclass method needs to call its private
+ field even if invoked from a subclass. The solution was to modify the subclass field
+ name using one or more prepended $.
+
+5) Use of Class.getDeclaredMethods() reflection will return Method objects having the transpiled
+ name, not the Java name. This could require some j2sNative adjustment
+ to strip the $... parameters from the name if that is needed.
+
+6) Use of Method.getParameterTypes() should work fine, provided class names
+ do not contain "_". This is because the transpiler converts "." to "_" when
+ creating the fully qualified JavaScript name.
+
+
+positive integers do not add to give negative numbers
+-----------------------------------------------------
+
+In Java, the following is true:
+
+ 2000000000 + 2000000000 == -294967296
+
+But in SwingJS, that will be 4000000000. So, for example, the following
+strategy will fail in SwingJS:
+
+ int newLength = lineBuf.length * 2;
+ if (newLength < 0) {
+ newLength = Integer.MAX_VALUE;
+ }
+
+"-1" in JavaScript is not 0xFFFFFFFF.
+
+And one must take care to not compare a negative number with a 32-bit mask. So
+
+(b & 0xFF000000) == 0xFF000000
+
+is true in Java for (int) b = -1, but is false in JavaScript, because 0xFF000000 is 4278190080,
+while (-1 & 0xFF000000) is, strangely enough, -16777216, and, in fact,
+
+(0xFF000000 & 0xFF000000) != 0xFF000000
+
+because -16777216 is not 4278190080.
+
+The fix is that one must compare similar operations:
+
+if ((b & 0xFF000000) == (0xFF000000 & 0xFF000000)) .....
+
+Importantly, the JavaScript Int32Array does behave properly. From
+the Firefox developer console:
+
+>> x = new Int32Array(1)
+<- Int32Array(1) [ 0 ]
+>> x[0] = 4000000000
+<- 4000000000
+>> x[0]
+<- -294967296
+
+Notice that, perhaps unexpectedly, the following two constructs produce
+different results in JavaScript:
+
+x = new Int32Array(1);
+b = x[0] = 4000000000;
+
+(b will be 4000000000)
+
+and
+
+x = new Int32Array(1);
+x[0] = 4000000000;
+b = x[0];
+
+(b will be -294967296)
+
+
+SwingJS leverages array typing to handle all byte and short arithmetic so as
+to ensure that any byte or short operation in JavaScript does give the same
+result in Java. The design decision to not also do this with integer math was
+a trade-off between performance and handling edge cases.
+
+
+ArrayIndexOutOfBounds
+---------------------
+
+You cannot implicitly throw an ArrayIndexOutOfBoundsException in JavaScript.
+JavaScript will simply return "undefined", not throw an Exception. So:
+
+boolean notAGoodIdeaIsOutOfBounds(String[] sa, int i) {
+ try {
+ return (sa[i] == sa[i]);
+ } catch (ArrayIndexOutOfBoundsException e) {
+ return false;
+ }
+}
+
+will work in Java but not in JavaScript. Code should not depend upon this sort
+of trap anyway, if you ask me.
+
+Throwable vs Error vs Exception
+-------------------------------
+
+True JavaScript errors are trapped as Throwable, whereas you can still trap
+Error and Exception as well. So if you want to be sure to catch any JavaScript
+error, use try{}catch (Throwable t){}, not try{}catch (Exception e){}.
+
+j
+ava.awt.Color
+--------------
+
+ColorSpace: only "support" CS_sRGB.
+
+ TODO -- any volunteers??
+
+
+javax.swing.JFileDialog
+-----------------------
+
+HTML5 cannot expose a file reading directory structure. But you certainly
+can still do file reading and writing. It just works a little differently.
+It's a simple modification:
+
+ b = new JButton("FileOpenDialog");
+ b.addActionListener(new ActionListener() {
+
+ @Override
+ public void actionPerformed(ActionEvent e) {
+ JFileChooser fc = new JFileChooser();
+ Test_Dialog.this.onDialogReturn(fc.showOpenDialog(Test_Dialog.this));
+ // Java will wait until the dialog is closed, then enter the onDialogReturn method.
+ // JavaScript will exit with NaN immediately, and then call back with its actual value
+ // asynchronously.
+ }
+
+ });
+
+ public void onDialogReturn(int value) {
+ if (value != Math.floor(value))
+ return; // in JavaScript, this will be NaN, indicating the dialog has been opened
+ // If we are here, the dialog has closed, in both Java and JavaScript.
+ System.out.println("int value is " + value);
+ }
+
+
+ @Override
+ public void propertyChange(PropertyChangeEvent event) {
+ Object val = event.getNewValue();
+ String name = event.getPropertyName();
+ System.out.println(name);
+ switch (event.getSource().getClass().getName()) {
+ case "javax.swing.JOptionPane":
+ switch (name) {
+ case "inputValue":
+ onDialogReturn(val);
+ return;
+ case "value":
+ if (val instanceof Integer)
+ onDialogReturn(((Integer) val).intValue());
+ else
+ onDialogReturn(val);
+ return;
+ }
+ break;
+ case "javax.swing.ColorChooserDialog":
+ switch (name) {
+ case "SelectedColor":
+ onDialogReturn(val);
+ return;
+ }
+ break;
+ case "javax.swing.JFileChooser":
+ switch (name) {
+ case "SelectedFile":
+ File file = (File) val;
+ byte[] array = (val == null ? null : /** @j2sNative file.秘bytes || */
+ null);
+ onDialogReturn("fileName is '" + file.getName() + "'\n\n" + new String(array));
+ return;
+ }
+ break;
+ }
+ System.out.println(
+ event.getSource().getClass().getName() + " " + event.getPropertyName() + ": " + event.getNewValue());
+ }
+
+
+Developers are encouraged to create a separate class that handles general calls to JFileDialog.
+An example class can be found in the SwingJS distribution as
+
+/sources/net.sf.j2s.java.core/src/javajs/async/AsyncFileChooser.java.
+
+
+javax.swing.JOptionPane dialogs
+-------------------------------
+
+For this action to work, the parentComponent must implement
+propertyChangeListener, and any call to JOptionPanel should allow for
+an asynchronous response, meaning that there is no actionable code following the
+call to the dialog opening.
+
+In addition, for compatibility with the Java version, implementation should
+wrap the call to getConfirmDialog or getOptionDialog in a method call to
+handle the Java:
+
+onDialogReturn(JOptionPane.showConfirmDialog(parentFrame,
+messageOrMessagePanel, "title", JOptionPane.OK_CANCEL_OPTION));
+
+Then parentFrame.propertyChange(event) should also call onDialogReturn.
+
+This will then work in both Java and JavaScript.
+
+Note that there is an int and an Object version of onDialogReturn().
+
+
+In JavaScript:
+
+The initial return from JOptionPane.showConfirmDialog and showMessageDialog
+will be (SwingJS) JDialog.ASYNCHRONOUS_INTEGER (NaN), testable as an impossible
+Java int value using ret != -(-ret) if the parent implements PropertyChangeListener, or -1
+(CLOSE_OPTION) if not.
+
+For showOptionDialog (which returns Object) or showInputDialog (which returns
+String), the initial return will be (SwingJS) JDialog.ASYNCHRONOUS_OBJECT, testable as
+((Object) ret) instanceof javax.swing.plaf.UIResource if the parent implements
+PropertyChangeListeneer, or null if not.
+
+The second return will be the desired return.
+
+In Java:
+
+The initial return will be the one and only modal final return.
+
+
+
+For full compatibility, The calling method must not continue beyond this
+call.
+
+All of the standard Java events associated with Components are also
+available.
+
+Certain fall back mechanisms are possible, where onReturn does not exist, but
+only for the following cases:
+
+
+For showMessageDialog, for WARNING_MESSAGE and ERROR_MESSAGE, a simple
+JavaScript alert() is used, returning 0 (OK_OPTION) or -1 (CLOSED_OPTION).
+
+For showInputDialog, if the message is a string, a simple JavaScript prompt()
+with input box is used, returning the entered string or null.
+
+For showConfirmDialog, a simple JavaScript confirm() is used, in which case:
+
+for YES_NO_OPTION: YES_OPTION or NO_OPTION
+
+for YES_NO_CANCEL_OPTION: YES_OPTION or CANCEL_OPTION
+
+for OK_CANCEL_OPTION or any other: OK_OPTION or CANCEL_OPTION
+
+Note that you should implement a response for CLOSED_OPTION for
+showConfirmDialog. For other dialogs, a null return indicates the dialog was
+closed, just as for Java.
+
+Developers are encouraged to create a separate class that handles general calls.
+An example class can be found in the SwingJS distribution as src/javajs/async/AsyncDialog.java.
+Very simple modifications to the Java allows asynchronous operation using AsyncDialog. Here
+is a simple "do you want to close this frame" example, where you can see that what we have
+done is to set the reply into an ActionListener that is defined in the constructor of
+the AsyncDisplay object:
+
+// Original:
+//
+// private void promptQuit() {
+// int sel = JOptionPane.showConfirmDialog(null, PROMPT_EXIT, NAME, JOptionPane.YES_NO_OPTION);
+// switch (sel) {
+// case JOptionPane.YES_OPTION:
+// resultsTab.clean();
+// seqs.dispose();
+// if (fromMain) {
+// System.exit(0);
+// }
+// break;
+// }
+// }
+
+ private void promptQuitAsync() {
+ new AsyncDialog(new ActionListener() {
+
+ @Override
+ public void actionPerformed(ActionEvent e) {
+ int sel = ((AsyncDialog)e.getSource()).getOption();
+ switch (sel) {
+ case JOptionPane.YES_OPTION:
+ resultsTab.clean();
+ seqs.dispose();
+ if (fromMain) {
+ System.exit(0);
+ }
+ break;
+ }
+ }}).showConfirmDialog(null, PROMPT_EXIT, NAME, JOptionPane.YES_NO_OPTION);
+ }
+
+Very simple!
+
+
+native methods
+--------------
+
+The J2S compiler ignores all static native method declarations.
+Anything of this nature needs to be implemented in JavaScript if it is needed,
+using j2sNative blocks:
+
+/**
+ * @j2sNative
+ *
+ * var putYourJavaScriptCodeHere
+ *
+ */
+
+ Note that if you follow that directly with a {...} block, then
+ the javadoc code will run in JavaScript, and the {...} code will run in Java.
+
+
+key Focus
+---------
+
+As of June, 2019, the keyboard focus manager is fully implemented.
+The one catch is that JTextPane and JTextArea, which already consume
+VK_TAB in Java, cannot use CTRL-TAB to continue a tabbing cycle around
+the components in a window. Instead, CTRL-TAB is absorbed by the browser.
+
+
+LookAndFeel and UI Classes
+--------------------------
+
+SwingJS implements the native browser look and feel as swingjs.plaf.HTML5LookAndFeel.
+There are small differences between all look and feels -- MacOS, Windows, SwingJS.
+
+Expert developers know how to coerce changes in the UI by subclassing the UI for a
+component. This probably will not work in SwingJS.
+
+Note that LookAndFeel in Java usually determines canvas size in a Frame because
+different operating systems (Mac OS vs Windows vs HTML5) will have
+different edge sizes on their frames. If you want to ensure a component size,
+use getContentPane().setPreferredSize().
+
+
+System.exit(0) does not stop all processes
+------------------------------------------
+
+Although System.ext(int) has been implemented in JavaScript, it just closes the
+frames, stops all pending javax.swing.Timer objects in the queue, and runs any
+threads added using Runtime.getRuntime().addShutdownHook(Thread).
+It may not stop all "threads." So don't rely on that.
+Applications are responsible for shutting down prior to executing System.exit(0).
+
+
+myClass.getField not implemented
+--------------------------------
+
+java.lang.reflect.Field is implemented minimally. It is not
+certain that Field.getDeclaringClass() will work. If you just want a
+value of a field, you can do this:
+
+/**
+ *@j2sNative
+ *
+ * return myClass[name]
+ */
+
+But that is not a java.lang.reflection.Field object.
+
+
+"window" and other reserved JavaScript names
+--------------------------------------------
+
+No reserved top-level JavaScript name is allowed for a package name. So, for example,
+one must rename packages such as "window" or "document" to names such as "win" or "doc".
+
+reserved field and method names
+-------------------------------
+
+In order to minimize the chance of added SwingJS field and method names colliding with ones
+developers might use in subclassing Java classes, we have added U+79D8 (first character of Mandarin
+"secret") to the characters already disrecommended by Java documentation ("$" and "_"). The only problem
+would be if you use that character followed by certain English words in certain classes. For example
+\u79D8canvas for JComponents (in java.awt.JSComponent) and \u79D8byte (in java.io.File).
+
+qualified field and method names
+--------------------------------
+
+Method names in SwingJS are fully qualified, meaning two methods with the same Java name but different
+parameters, such as write(int) and write(double), must not have the same name in JavaScript. (In this
+case, we will have write$I and write$D.) However, in certain cases it may be desirable to leave the
+method names unqualified. In particular, when an interface actually represents a JavaScript object,
+the transpiler can leave a method name unqualified. The default situation for this is a class name
+includes ".api.js" (case-sensitive). This means that any method in any class in a package js within
+a package api, or any private interface js that has an outer interface api, will have all-unqualified
+methods. An example of this is swingjs.plaf.JSComboPopupList, which needs to communicate with a jQuery
+object directly using the following interface:
+
+ private interface api {
+
+ interface js extends JQueryObject {
+
+ abstract js j2sCB(Object options);
+
+ abstract Object[] j2sCB(String method);
+
+ abstract Object[] j2sCB(String method, Object o);
+
+ abstract Object[] j2sCB(String method, int i);
+
+ abstract int j2sCB(String OPTION, String name);
+
+ }
+ }
+
+Notice that all these variants of j2sCB() will call the same method in JavaScript by design.
+
+
+missing Math methods
+--------------------
+
+java.lang.Math is worked out, but some methods are missing, either because they
+involve long integer value that are inaccessible in JavaScript, or because I just
+didn't implement them. This is a result of continued Java development.
+It is easy enough to add these methods if you have the source. They go into j2sClazz.js,
+which is combined with other initial libraries into swingjs2.js by build_site.xml
+
+
+Component.getGraphics(), Graphics.dispose()
+-------------------------------------------
+
+Use of component.getGraphics() is discouraged in Java and in SwingJS.
+Specifically in SwingJS, any call to component.getGraphics() or
+BufferedImage.createGraphics() or Graphics.create(...) should be matched with graphics.dispose(),
+particularly when it is called outside the context of a paint(Graphics)
+call from the system.
+
+If you see your graphics scrolling down the page with each repaint,
+look for where you have used Component.getGraphics() and not Graphics.dispose().
+For example, this will definitely NOT work in SwingJS:
+
+ this.paint(getGraphics())
+
+and really should not work in Java, either, as it is technically a resource memory leak.
+
+Instead, if you really do not want to use repaint(), use this:
+
+ Graphics g = getGraphics();
+ paint(g);
+ g.dispose();
+
+
+
+Graphics.setClip()
+------------------
+
+The HTML5 canvas.clip() method is permanent. You can only reset the clip using
+save/restore. This is different from Java, where you can temporarily change it using
+
+ Shape oldClip = Graphics.getClip();
+ Graphics.setClip(newClip);
+ ...
+ Graphics.setClip(oldClip);
+
+If you need to do something like this, you must schedule the paints
+to not have overlapping clip needs.
+
+
+MAJOR ISSUES--for Bob and Udo within SwingJS
+============================================
+
+fonts
+-----
+
+Fonts and FontMetrics will all be handled in JavaScript. Font matching will
+not be exact, and composite (drawn) fonts will not be supported.
+
+SwingJS handles calls such as font.getFontMetrics(g).stringWidth("xxx") by
+creating a <div> containing that text, placing it in an obscure location on
+the page, and reading div.getBoundingClientRect(). This is a VERY precise
+value, but can be a pixel or two off from what Java reports for the same font.
+
+
+OS-dependent classes
+--------------------
+
+Static classes such as:
+
+ java.awt.Toolkit
+ java.awt.GraphicsEnvironment
+
+
+which are created using Class.forName are implemented using classes in the swingjs package.
+
+AWTAccessor is not implemented.
+
+
+AWT component peers and component "ui" user interfaces
+------------------------------------------------------
+
+ComponentPeer is a class that represents a native AWT component.
+Components with such peers are called "heavy-weight" components.
+They are expected to do the dirty work of graphics drawing.
+
+Java Swing implements peers only for JApplet, JDialog, JFrame, and JWindow.
+References to such objects have been removed, but clearly there must be
+some connection to similar DOM objects, even for "light-weight" components.
+
+
+
+MAJOR ISSUES--to be resolved by implementers
+============================================
+
+fonts
+-----
+
+Glyph/composite/outline fonts are not supported.
+
+
+
+threads
+-------
+
+Thread locking and synchronization are not relevant to JavaScript.
+Thus, anything requiring "notify.." or "waitFor.." could be a serious issue.
+
+All threading must be "faked" in JavaScript. Specifically not available is:
+
+ Thread.sleep()
+
+javax.swing.AbstractButton#doClick(pressTime) will not work, as it requires Thread.sleep();
+
+However, java.lang.Thread itself is implemented and used extensively.
+
+Methods thread.start() and thread.run() both work fine.
+
+For simple applications that use Thread.sleep() just to have a delay, as in a frame rate, for
+example, one can use javax.swing.Timer instead. That is fully implemented.
+
+Likewise, java.util.Timer can be replaced with no loss of performance with javax.Swing.Timer.
+Note that java.util.TimerTask is implemented, but it can also be replaced by an implementation of Runnable.
+
+task = new TimerTask(){....};
+t = new java.util.Timer();
+t.schedule(task, 0, 1);
+
+becomes
+
+task = new TimerTask(){....}; // or task = new Runnable() {...}
+t = new javax.swing.Timer(1, new ActionListener() {
+ @Override
+ public void actionPerformed(ActionEvent e) {
+ task.run();
+ }
+};
+t.setInitialDelay(0); // not particularly necessary
+t.start();
+
+In addition, SwingJS provides swingjs.JSThread, which can be subclassed
+if desired. This class allows simple
+
+ while(!interrupted()){
+ wait()
+ ...
+ }
+
+action through an asynchronous function run1(mode). For example:
+
+ protected void run1(int mode) {
+ try {
+ while (true)
+ switch (mode) {
+ case INIT:
+ // once-through stuff here
+ mode = LOOP;
+ break;
+ case LOOP:
+ if (!doDispatch || isInterrupted()) {
+ mode = DONE;
+ } else {
+ Runnable r = new Runnable() {
+ public void run() {
+ // put the loop code here
+ }
+ };
+ dispatchAndReturn(r);
+ if (isJS)
+ return;
+ }
+ break;
+ // add more cases as needed
+ case DONE:
+ // finish up here
+ if (isInterrupted())
+ return;
+ // or here
+ break;
+ }
+ } finally {
+ // stuff here to be executed after each loop in JS or at the end in Java
+ }
+ }
+
+image loading
+-------------
+- All image loading in SwingJS is synchronous. A MediaTracker call will immediately return "complete".
+ However, it still may take one system clock tick to fully load images. Thus, it is recommended that
+ images be preloaded in the static block of the applet if it is necessary that they be available in init().
+ This is only an issue if you are trying to access the pixel buffer of the image in JavaScript.
+
+- Applet.getImage(path, name) will return null if the image does not exist.
+
+- BufferedImage: only "support" imageType RGB and ARGB
+
+ -BH: This is a temporary edit, just to get us started. Certainly GRAY will be needed
+
+
+BigInteger and BigDecimal
+-------------------------
+
+java.math.BigInteger is fully supported; java.math.BigDecimal is roughed
+in and not fully tested (07/2019).
+
+Both classes present significant issues for JavaScript, as they are based in
+Java's 64-bit long for all their operations. Here is the JavaDoc note I added
+to BigInteger:
+
+ * SwingJS note: Because of the limitations of JavaScript with regard
+ * to long-integer bit storage as a double, this implementation drops
+ * the integer storage bit length to 24, giving 48 for long and leaving
+ * the last 16 bits clear for the exponent of the double number. This should
+ * not affect performance significantly. It does increase the storage
+ * size by about 33%. By bringing an "int" to 3 bytes, we can easily construct
+ * and use byte[] data intended for the original BitSet.
+
+"Easily" may be a bit strong there. This was a serious challenge.
+
+BigDecimal seems to run normally, but in order to do that, my hack involves
+reducing the size of an integer that is allowed to be stored as such and not
+in byte[] as a BigInteger. I'm sure there is a performance hit, but it does work.
+
+no format internationalization
+------------------------------
+
+For now, just en for number and date formatters
+
+no winding rules
+----------------
+
+ When filling a graphic, only nonzero winding rule is implemented in HTML5 Canvas2D.
+
+
+
+text-related field implementation
+---------------------------------
+
+Text fields are:
+
+JTextField (JavaScript <input type="text">)
+JTextArea (JavaScript <textarea>)
+JTextPane (JavaScript <div>)
+JEditorPane (JavaScript <div>)
+
+For the initial implementation, we don't implement infinite undo/redo, and the abstract
+document model is much less elaborate. Only PlainDocument (in the form of JSPlainDocument)
+is implemented. The Document returned by JTextField.getDocument() is a javax.swing.text.Document.
+
+All scrolling is handled by HTML5. javax.swing.AutoScroller is not implemented.
+public static methods .stop, .isRunning, .processMouseDragged require true Java threading
+and so are not implmented. javax.swing.text.View and its subclasses are not implemented.
+
+The JS document model does not allow two text fields to address the same underlying document.
+
+JavaScript is slightly different from Java in that the field value is changed asynchronously after
+the keypressed event, so Java actions that are keyed to KEY_PRESSED may not pick up the new
+key value even after SwingUtilities.invokeLater() is called. Thus, key pressed actions may need
+to be recorded after a key released event instead.
+
+Formatter/Regex limitations
+---------------------------
+
+Some browsers cannot process Regex "look-behind" process such as (?<=\W)
+java.util.regex.Matcher and Pattern use JavaScript's RegExp object rather than
+the native Java object. These are not identical. Only flags /igm are supported.
+Matcher.start(groupID) is not supported.
+
+java.util.Formatter will function correctly for all standard %... patterns.
+
+integer 1/0 == Infinity
+-----------------------
+
+1/0 in Java throws "java.lang.ArithmeticException: / by zero", but in JavaScript is just Infinity.
+
+
+
+Summary
+-------
+
+These are all the known limitations of SwingJS. We have not found any of these limitations
+to be show-stoppers. The primary issue for newcomers to SwingJS is having the source code.
+You must check that source code for all your library jar files is available or, if you
+choose, you will need to decompile those classes. We have used decompilation on some projects,
+and it works just fine. So, technically, all we really need are JAR/class files. But the
+source is by far superior. It's generally prettier, and it has the license information that
+may or may not be present with the JAR or class files. Use class files at your own risk.
+
+Bob Hanson
+2019.08.16
+
+
+Additional Issues
+-----------------
+
+Annotation is working for classes, methods, and fields (12/22/19). Method reflection, however,
+is limited. Interfaces do not expose their methods, as the transpiler does not actually transpile
+the interfaces themselves. And method reflection only includes annotated methods.
+
+java.util.concurrent is not fully elaborated. This package is rewritten to not actually use the
+memory handling capabilities of concurrency, which JavaScript does not have access to.
+
+System.getProperties() just returns a minimal set of properties.
+
+
-20200317182149
+20201127032339
--- /dev/null
+Notes
+=====
+
+---IMPORTANT CHARACTER SET NOTE---
+
+It is critical that all development work in Java2Script
+be done in UTF-8. This means:
+
+- making sure your Eclipse project is set up for UTF-8 (not the Eclipse default?)
+- making sure your server can serve up UTF-8 by default for any browser-loaded files
+- making sure you don't edit a Java2Script class file or one of the site .js files
+ using a non-UTF-8 editor. It may replace non-Latin characters with "?" or garbage.
+- making sure that your web pages are delivered with proper headings indicating HTML5 and UTF-8
+
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="utf-8">
+
+Note that the DOCTYPE tag is critical for some browsers to switch into HTML5 mode. (MSIE?)
+
+
+
+
+In particular, the Mandarin character 秘 (mi; "secret") is used extensively throughout
+the SwingJS class files to distinguish j2s-specific fields and methods that must not
+ever be shadowed or overridden by subclasses. For example, we see in java.lang.Thread.java:
+
+ public static JSThread 秘thisThread;
+
+----------------------------------
+
+
+updated 12/6/2020 -- note about restrictions on long, including BitSet and Scanner
+updated 3/21/2020 -- adds note about HashMap, Hashtable, and HashSet iterator ordering
+updated 3/20/2020 -- adds note about interning, new String("xxx"), and "xxx"
+updated 2/26/2020 -- adds Graphics.setClip issue
+updated 12/22/19 -- additional issues
+updated 11/03/19 -- adds information about File.exists() and points to src/javajs/async
+updated 10/26/19 -- adds information about File.createTempFile()
+updated 8/16/19 -- minor typos and added summary paragraph
+updated 7/19/19 -- clarification that AWT and Swing classes are supported directly
+updated 5/13/19 -- Mandarin U+79D8 reserved character; Missing Math methods; int and long
+updated 5/10/19 -- adds a section on static issues in multi-(duplicate)-applet pages
+updated 1/4/19 -- nio
+updated 9/15/18 -- adds integer 1/0 == Infinity
+updated 7/24/18 -- most classes replaced with https://github.com/frohoff/jdk8u-jdk
+updated 6/5/17 -- reserved package name "window"
+updated 3/11/17 -- myClass.getField
+updated 3/7/17 -- overloading of JSplitPane.setDividerLocation
+updated 3/2/17 -- more indication of classes not implemented (KeyListener)
+
+=============================================================================
+SwingJS and OpenJDK 8+
+=============================================================================
+
+SwingJS implements a wide range of the Java language in JavaScript. The base
+version for this implementation is OpenJDK8. some classes are implemented using
+older source code, and there are some missing methods. For the most part, this is
+no real problem. You can add or modify any java class just be adding it as source
+in your project. Or (preferably) you can contact me, and I can get it into the
+distribution. Or (even more preferably) you can do that via a patch submission.
+
+=================
+DESIGN PHILOSOPHY
+=================
+
+The java2script/SwingJS design goal is to recreate a recognizable, easily debuggable
+equivalent in JavaScript for as much of Java as practical. This means, for example,
+that one can call in JavaScript
+
+ new java.util.Hashtable()
+
+and for all practical purposes it will appear that Java is running.
+
+
+Method and Field Disambiguation
+-------------------------------
+
+SwingJS has no problem with the overloading of methods, for example:
+
+ public void print(int b);
+ public void print(float b);
+
+JavaScript does not allow overloading of methods, and the common practice in
+Java of naming a field the same as a method -- isAllowed and isAllowed() -- is
+not possible in JavaScript. As a result, SwingJS implements "fully-qualified"
+method names using "$" parameter type separation. Thus, these methods in SwingJS
+will be referred to as print$I and print$F. The rules for this encoding are
+relatively simple:
+
+1. The seven primitive types in Java are encoded $I (int), $L (long), $F (float),
+$D (double), $B (byte) $Z (boolean), and $H (short).
+
+2. String and Object are encoded as $S and $O, respectively.
+
+3. "java_lang_" is dropped for all other classes in the java.lang package (as in Java).
+ For example: $StringBuffer, not $java_lang_StringBuffer
+
+4. All other classes are encoded as
+
+ "$" + Class.getName().replace(".","_")
+
+For example, in Java we see:
+
+ public void equals(Object o) {...}
+
+Whereas in SwingJS we have:
+
+ Clazz.newMeth(C$, 'equals$O', function (o) {...}
+
+And
+
+ this.getContentPane().add(bar, "North");
+
+becomes
+
+ this.getContentPane$().add$java_awt_Component$O(bar, "North");
+
+5. Arrays are indicated with appended "A" for each level. So
+
+ setDataVector(Object[][] dataVector, Object[] columnIdentifiers)
+
+becomes
+
+ setDataVector$OAA$OA(dataVector, columnIdentifiers)
+
+(It is recognized that this design does introduce a bit of ambiguity, in that
+ in principal there could be user class named XA and X in the same package,
+ and methods a(X[]) and a(XA) in the same class that cannot be distinguished.
+ The benefit of this simple system, however, triumphed over the unlikelyhood
+ of that scenario.) The transpiler could be set to flag this possibility.
+
+6. Constructors are prepended with "c$". So
+
+ public JLabel(String text) {...}
+
+becomes:
+
+ Clazz.newMeth(C$, 'c$$S', function (text) {...});
+
+Field disambiguation involves prepending. In Java, a class and its subclass
+can both have the same field name, such as
+
+ boolean visible;
+
+When this happens, it is called "shadowing", and though not recommended, Java allows
+it. The Java2Script transpiler will prepend such shadowing fields with "$" so that the
+subclass instance has both "visible" (for use in its methods inherited from its
+superclass) and "$visible" (for its own methods). Thus, we might see in Java:
+
+ this.visible = super.visible;
+
+while in SwingJS we will see:
+
+ this.$visible=this.visible;
+
+since JavaScript does not have the "super" keyword.
+
+
+
+Parameterless methods such as toString() are appended with "$" to become toString$().
+The one exception to this rule is private methods, which are saved in (truly) private
+array in the class (and are not accessible by reflection). Private parameterless
+methods retain their simple Java name, since they cannot conflict with field names.
+
+This renaming of methods has a few consequences, which are discussed more fully below.
+See particularly the section on "qualified field and method names", where it is described
+how you can use packages or classes or interfaces with ".api.js" in them to represent JavaScript
+objects for which all method names are to be left unqualified. Note that it is not
+possible to cherry-pick methods to be unqualified; only full packages, classes or
+interfaces can hold this status.
+
+The swingjs.api.js package in particular contains a number of useful interfaces that
+you can import into your project for JavaScript-specific capabilities.
+
+
+Applet vs. Application
+----------------------
+
+One of the very cool aspects of SwingJS is that it doesn't particularly matter if a browser-based
+Java app is an "applet" or an "application". We don't need JNLP (Java Network Launch Protocol)
+because now we can just start up any Java application in a browser just as easily as any applet.
+The associative array that passes information to the SwingJS applet (information that formerly
+might have been part of the APPLET tag, such as width, height, and codebase, always referred to
+in our writing as "the Info array") allows the option to specify the JApplet/Applet "code"
+class or the application "main" class. Either one will run just fine.
+
+
+Performance
+-----------
+
+Obviously, there are limitations. One is performance, but we have seen reproducible
+performance at 1/6 - 1/3 the speed of Java. Achieving this performance may require
+some refactoring of the Java to make it more efficient in both Java and JavaScript.
+"for" loops need to be more carefully crafted; use of "new" and "instanceof" need to be
+minimized in critical areas. Note that method overloading -- that is, the same method name
+with different parameters, such as read(int) and read(byte) -- is no longer any problem.
+
+
+Threads
+-------
+
+Although there is only a single thread in JavaScript, meaning Thread.wait(), Thread.sleep(int) and
+Thread.notify() cannot be reproduced, we have found that this is not a serious limitation.
+For example, javax.swing.Timer() works perfectly in JavaScript. All it means is that threads
+that use sleep(int) or notify() must be refactored to allow Timer-like callbacks. That is,
+they must allow full exit and re-entry of Thread.run(), not the typical while/sleep motif.
+
+The key is to create a state-based run() that can be exited and re-entered in JavaScript.
+
+
+Static fields
+-------------
+
+Final static primitive "constant" fields (String, boolean, int, etc.) such as
+
+static final int TEST = 3;
+static final String MY_STRING = "my " + "string";
+
+are converted to their primitive form automatically by the Eclipse Java compiler
+and do not appear in the JavaScript by their names.
+
+Other static fields are properties of their class and can be used as expected.
+
+Note, however, that SwingJS runs all "Java" code on a page in a common "jvm"
+(like older versions of Java). So, like the older Java schema, the JavaScript
+equivalents of both applets and applications will share all of their static
+fields and methods. This includes java.lang.System.
+
+Basically, SwingJS implementations of Java run in a browser page-based sandbox
+instead of an applet-specific one.
+
+In general, this is no problem. But if we are to implement pages with
+multiple applets present, we must be sure to only have static references
+that are "final" or specifically meant to be shared in a JavaScript
+environment only (since they will not be shared in Java).
+
+A simple solution, if static non-constant references are needed, is to attach the
+field to Thread.currentThread.threadGroup(), which is an applet-specific reference.
+Be sure, if you do this, that you use explicit setters and getters:
+
+For example,
+
+private static String myvar;
+
+...
+
+public void setMyVar(String x) {
+ ThreadGroup g = Thread.currentThread().threadGroup();
+ /**
+ * @j2sNative g._myvar = x;
+ *
+ */
+ {
+ myvar = x;
+ }
+}
+
+public String getMyVar() {
+ ThreadGroup g = Thread.currentThread().threadGroup();
+ /**
+ * @j2sNative return g._myvar || null;
+ *
+ */
+ {
+ return myvar;
+ }
+}
+
+ in Java will get and set x the same in JavaScript and in Java.
+
+
+A convenient way to do this in general is to supply a singleton class with
+explicitly private-only constructors and then refer to it in Java and in JavaScript
+instead of using static field, referring to myclass.getIntance().xxx instead of
+myclass.xxx in Java (and JavaScript).
+
+This was done extensively in the Jalview project. See jalview.bin.Instance.
+
+
+Helper Packages -- swingjs/ and javajs/
+---------------------------------------
+
+The SwingJS library is the swingjs/ package. There are interfaces that may be of assistance
+in swingjs/api, but other than that, it is not recommended that developers access classes in
+this package. The "public" nature of their methods is really an internal necessity.
+
+In addition to swingjs/, though, there are several useful classes in the javajs/ package
+that could be very useful. This package is a stand-alone package that can be
+cloned in any Java project that also would be great to have in any JavaScript project
+-- SwingJS-related or not. Functionality ranges from reading and writing various file
+formats, including PDF, BMP, PNG, GIF, JPG, JSON, ZIP, and CompoundDocument formats.
+
+A variety of highly efficient three- and four-dimensional point, vector, matrix, and
+quaternion classes are included, as they were developed for JSmol and inherited from that
+project.
+
+Of particular interest should be javajs/async/, which includes
+
+javajs.async.Async
+javajs.async.AsyncColorChooser
+javajs.async.AsyncDialog
+javajs.async.AsyncFileChooser
+
+See javajs.async.Async JavaDoc comments for a full description of
+these useful classes.
+
+
+Modal Dialogs
+-------------
+
+Although true modal dialogs are not possible with only one thread, a functional equivalent --
+asynchronous modal dialogs -- is relatively easy to set up. All the JOptionPane dialogs will
+return PropertyChangeEvents to signal that they have been disposed of and containing the results.
+See below and classes in the javajs.async package.
+
+
+Native calls
+------------
+
+Native calls in Java are calls to operating system methods that are not in Java. JavaScript
+has no access to these, of course, and they must all be replaced by JavaScript equivalents.
+Fortunately, they are not common, and those that are present in Java (for example, in calculating
+checksums in ZIP file creation) are at a low enough level that most developers do not utilize them
+or do not even have access to them. All native calls in Java classes have been replaced by
+Java equivalents.
+
+
+Swing GUI Peers and UIClasses
+-----------------------------
+
+One of the biggest adaptations introduced in SwingJS is in the area of the graphical
+user interface. The issue here is complex but workable. In Java there are two background
+concepts -- the Component "peer" (one per "heavy-weight" component, such as a Frame) and the
+component "uiClass" (one per component, such as JButton or JTextField).
+
+Peers are native objects of the operating system. These are the virtual buttons and text areas
+that the user is interacting with at a very base level. Their events are being passed on to
+Java or the browser by the operating system. UI classes provide a consistent "look and feel"
+for these native objects, rendering them onto the native window canvas and handling all
+user-generated events. They paint the borders, the backgrounds, the highlights, of every
+control you see in Java. There is one-to-one correspondence of Swing classes and UI classes.
+Setting the Look and Feel for a project amounts to selecting the directory from which to draw
+these UI classes. The UI classes can be found in the javax.swing.plaf ("platform look and feel")
+package.
+
+Early on in the development of SwingJS, we decided not to fully reproduce the painfully detailed
+bit-by-bit painting of controls as is done in Java. Instead, we felt it was wiser to utilize the standard
+HTML5 UI capabilities as much as possible, using DIV, and INPUT especially, with extensive use
+of CSS and sometimes jQuery (menus, and sliders, for example). Thus, we have created a new
+set of UIs -- the "HTML5 Look and Feel". These classes can be found in swingjs.plaf. Besides being
+more adaptable, this approach allows far more versatility to SwingJS developers, allowing them
+to modify the GUI to suit their needs if desired.
+
+In SwingJS, since we have no access to native peers except through the browser DOM,
+it seemed logical to merge the peer and UI idea. So instead of having one peer per heavy-weight control and
+one UI class instance for each control type, we just have one UI class instance per control, and
+that UI class instance is what is being referred to when a "peer" is notified.
+
+In some ways this is a throw back to when all of Swing's components were subclasses of
+specific AWT components such as Button and List. These "heavy-weight components" all had their
+own individual native peers and thus automatically took on the look and feel provided by the OS.
+Later Swing versions implemented full look and feel for all peers, leaving only JDialog, JFrame,
+and a few other classes to have native peers. But in SwingJS we have again a 1:1 map of component
+and UI class/peer instance.
+
+The origin of most issues (read "bugs") in relation to the GUI will probably be found in the
+swingjs.plaf JSxxxxUI.java code.
+
+
+Swing-only Components -- no longer an issue
+-------------------------------------------
+
+Swing was introduced into Java well after the Java Abstract Window Toolkit (AWT) was well
+established. As such, its designers chose to allow AWT controls such as Button and List to be used
+alongside their Swing counterparts JButton and JList. Reading the code, it is clear that this
+design choice posed a huge headache for Swing class developers.
+
+For SwingJS, we decided from the beginning NOT to allow this mixed-mode programming and
+instead to require that all components be Swing components.
+
+However, this is no longer an issue. All AWT components in SwingJS are now subclasses of
+javax.swing.JComponent. So far, we have found no problem with this.
+
+
+The a2s Adapter Package
+-----------------------
+
+Originally, we thought that we would restrict ourselves to JApplets only. That is, only
+Swing-based applets. But as we worked, we discovered that there are a lot of great
+applets out there that are pre-Swing pure-AWT java.applet.Applet applets. Our problem was
+that we also wanted it to be possible to quickly adapt these applets to JavaScript as well.
+
+The solution turned out to be simple: Write a package (a2s) that recreates the interface for
+non-Swing components as subclasses of Swing components. Thus, a2s.Button subclasses javax.swing.JButton
+but also accepts all of the methods of java.awt.Button. This works amazingly well, with a few
+special adaptations to the core javax.swing to be "AWT-aware." All AWT components now subclass
+a2s components, which in turn subclass JComponents. So no changes in code are necessary. We have
+successfully transpiled over 500 applets using this strategy. (Kind of surprising, actually, that
+the original Java developers did not see that option. But we have a hindsight advantage here.)
+
+
+Working with Files
+==================
+
+Simple String file names are not optimal for passing information about
+read files within SwingJS applications.
+
+All work with files should either use Path or File objects exclusively.
+These objects, after a file is read or checked for existence, will already
+contain the file byte[] data. Doing something like this:
+
+File f = File("./test.dat");
+boolean isOK = f.exists();
+
+will load f with its byte[] data, if the file exists.
+
+But if after that, we use:
+
+File f2 = new File(f.getAbsolutePath());
+
+f2 will not contain that data. Such copying should be done as:
+
+File f2 = new File(f);
+
+in which case, the byte[] data will be transferred.
+
+
+SwingJS uses the following criteria to determine if File.exists() returns true:
+
+(1) if this File object has been used directly to read data, or
+(2) if reading data using this File object is successful.
+
+Note that you cannot check to see if a file exists before input or if it
+was actually written or if it already exists prior to writing in SwingJS.
+
+Thus, you should check each use of file.exists() carefully, and if necessary, provide a J2sNative
+block that gives an appropriate "OK" message, for example:
+
+(/** @j2sNative 1 ? false : */ outputfile.exits())
+
+or
+
+(/** @j2sNative 1 ? true : */ inputfile.exits())
+
+Temporary files can be created in SwingJS. SwingJS will maintain a pseudo-filesystem for files
+created with File.createTempFile(). This is useful in that closure of writing to a temporary file
+does not generate a pseudo-download to the user's machine.
+
+
+UNIMPLEMENTED CLASSES BY DESIGN
+===============================
+
+The SwingJS implementation of the following classes are present
+in a way that gracefully bypasses their functionality:
+
+accessibility
+security
+serialization
+
+
+
+TODO LIST FOR UNIMPLEMENTED CLASSES
+===================================
+
+JEditorPane (minimal implementation) - DONE 12/2018; some issues still
+JSplitPane - DONE 8/2018
+JTabbedPane - DONE 10/2018
+JTree - done 12/2019
+
+
+MINOR ISSUES--required some rewriting/refactoring by Bob and Udo
+================================================================
+
+Thread.currentThread() == dispatchThread
+
+
+MINOR ISSUES--requiring some rewriting/refactoring outside of SwingJS
+=====================================================================
+
+See below for a full discussion.
+
+Restrictions on long
+Restriction on BitSet and Scanner
+HashMap, Hashtable, and HashSet iterator ordering
+interning, new String("xxx") vs "xxx"
+Names with "$" and "_"
+positive integers do not add to give negative numbers
+ArrayIndexOutOfBounds
+java.awt.Color
+native methods
+javax.swing.JFileDialog
+key focus
+LookAndFeel and UI Classes
+System.exit(0) does not stop all processes
+list cell renderers must be JComponents
+myClass.getField not implemented
+"window" and other reserved JavaScript names
+reserved field and method names
+qualified field and method names
+missing Math methods
+Component.getGraphics(), Graphics.dispose()
+Graphics.setClip()
+
+MAJOR ISSUES--for Bob and Udo within SwingJS
+============================================
+
+fonts
+OS-dependent classes
+AWT component peers
+some aspects of reflection
+
+MAJOR ISSUES--to be resolved by implementers
+============================================
+
+fonts
+threads
+modal dialogs
+image loading
+BigDecimal not fully implemented
+no format internationalization
+no winding rules
+text-related field implementation
+Formatter/Regex limitations
+integer 1/0 == Infinity
+
+========================================================================
+
+DISCUSS
+=======
+
+Table row/col sorter needs checking after removal of java.text.Collator references
+
+I had to move all of SunHints class to RenderingHints, or the
+two classes could not be loaded. Shouldn't be a problem, I think. The sun classes are
+not accessible to developers in Java anyway, since they are generally package private.
+
+==========================================================================
+
+//////////////////////////////////////////////////////////////////////////////
+
+UNIMPLEMENTED CLASSES
+=====================
+
+accessibility
+-------------
+
+All Accessibility handling has been commented out to save the download footprint.
+This removes the need for sun.misc.SharedSecrets as well.
+Nothing says we could not implement accessibility. We just didn't.
+
+
+security
+--------
+
+All JavaScript security is handled by the browser natively.
+Thus, Java security checking is no longer necessary, and
+java.security.AccessController has been simplified to work without
+native security checking.
+
+Note that private methods in a class are REALLY private.
+
+
+serialization
+-------------
+
+All serialization has been removed. It was never very useful for Swing anyway,
+because one needs exactly the same Java version to save and restore serialized objects.
+
+
+keyboard accelerators and mnemonics
+-----------------------------------
+
+This work was completed in the spring of 2019. Note that in a browser, some
+key strokes, particularly CTRL-keys, are not available. Bummer.
+
+
+MINOR ISSUES--required some rewriting/refactoring by Bob and Udo
+================================================================
+
+
+Thread.currentThread() == dispatchThread
+----------------------------------------
+
+changed to JSToolkit.isDispatchThread()
+
+
+MINOR ISSUES--requiring some rewriting/refactoring outside of SwingJS
+=====================================================================
+
+restrictions on long
+--------------------
+
+Java's 64-bit long type is not supported in JavaScript. There is no Int64Array in JavaScript,
+and 0x20000000000000 + 1 evaluates to 0x20000000000000, not 0x20000000000001.
+(Likewise, -0x20000000000000 - 1 is left unchanged.)
+
+The largest "integer" value in JavaScript is 9007199254740991 (9.007199254740991E13, or 0x1FFFFFFFFFFFFFF).
+Effectively, you get to use only 53 bits of the long, not 64. Trying to set a long larger than
+0x1FFFFFFFFFFFFFF or smaller than -0x1FFFFFFFFFFFFFF will result in a NumberFormatException.
+
+The transpiler handles conversion to long the same as Java for all cases other than from double.
+
+For small double values, there is no problem, and, in fact, this is a known trick used to round
+doubles and floats toward zero:
+
+double d;
+d = (long) 3.8;
+assert(d == 3);
+d = (long) -3.8;
+assert(d == -3);
+
+SwingJS will evaluate (long) d as 0 for d > 9007199254740991
+or d < -9007199254740991, same as Java returns for Double.NaN.
+So, in Java we have:
+
+ assert(((long) Double.NaN) == 0);
+ assert(((int) Double.NaN) == 0);
+ assert(((long) Float.NaN) == 0);
+ assert(((int) Float.NaN) == 0);
+
+and also, in JavaScript only, we also have:
+
+ double d = 0x2000000000000L;
+ assert(((long) d) == 0);
+
+
+restrictions on BitSet and Scanner
+----------------------------------
+
+Because of the issue of long being only 53 bits, any time a method returns a long value, considerations must
+be made as to whether this will work in JavaScript. In particular, BitSet and Scanner have issues.
+
+In SwingJS, java.util.BitSet has been implemented as a 32-bit integer-based bitset. This was no problem in
+Java 6, but starting with Java 7, a method was added to BitSet that allows for the extraction of the
+underlying long[] word data. This is not work in JavaScript. Instead, SwingJS java.util.Bitset.toLongArray() will deliver
+32-bit int[] data.
+
+SwingJS Scanner has hasNextLong() and nextLong(), and although it will scan through long numbers,
+Scanner will choke on long numbers greater than the JavaScript 53-bit limit. hasNextLong() will
+return false, and nextLong() will throw an InputMismatchException triggered by the NumberFormatException
+thrown by Long.parseLong().
+
+
+HashMap, Hashtable, and HashSet iterator ordering
+-------------------------------------------------
+
+In Java, iterators for HashMap, Hashtable, and HashSet do not guarantee any particular order.
+From the HashMap documentation for Java 8:
+
+ This class makes no guarantees as to the order of the map; in particular, it does not
+ guarantee that the order will remain constant over time.
+
+Likewise, for HashSet (because it is simply a convenience method for HashMap<Object,PRESENT>:
+
+ [HashSet] makes no guarantees as to the iteration order of the set.
+
+JavaScript's Map object is different. It is basically a LinkedHashMap, so it guarantees iteration
+in order of object addition.
+
+Starting with java2script 3.2.9.v1, these classes use the JavaScript Map object rather than hash codes
+whenever all keys are strictly of JavaScript typeof "string". If any key is introduced that is not a string, the
+implementation falls back to using hash codes, the same as Java.
+
+Note strings created using new String("xxxx") are NOT typeof "string"; they are typeof "object".
+
+The result is significantly faster performance (3-12 x faster) than originally, and up to 3 x faster
+performance in JavaScript than in Java itself. Right. Faster than Java.
+
+The JavaScript Map implementation is implemented UNLESS the constructor used is the one that
+specifies both initial capacity and load factor in their constructor. Thus,
+
+new Hashtable()
+new HashMap()
+new HashMap(16)
+new HashSet()
+
+all use the JavaScript Map. But
+
+new Hashtable(11, 0.75f)
+new HashMap(16, 0.75f)
+new HashSet(16, 0.75f)
+
+do not.
+
+This design allows for opting out of the JavaScript Map use in order to retain the exact behavior of
+iterators in JavaScript as in Java.
+
+
+interning, new String("xxx") vs "xxx"
+-------------------------------------
+
+Note that the following are true in JavaScript:
+
+typeof new String("xxxx") == "object"
+typeof "xxxx" == "string"
+var s = "x";typeof ("xxx" + s) == "string"
+
+There is no equivalence to this behavior in Java, where a String is a String is a String.
+
+Be aware that SwingJS does not always create a JavaScript String object using JavaScript's
+new String(...) constructor. It only does this for Java new String("xxxx") or new String(new String()).
+
+In all other cases, new String(...) (in Java) results in a simple "xxxx" string in JavaScript.
+That is, it will be JavaScript typeof "string", not typeof "object".
+
+The reason for this design is that several classes in the Java core use toString()
+methods that return new String(), and those classes that do that would cause a JavaScript error
+if implicitly stringified if new String() returned a JavaScript String object.
+
+This is fine in JavaScript
+
+test1 = function() { return { toString:function(){ return "OK" } } }
+"testing" + new test1()
+>> "testingOK"
+
+But for whatever reason in JavaScript:
+
+test2 = function() { return { toString:function(){ return new String("OK") } } }
+"testing" + new test2()
+>> Uncaught TypeError: Cannot convert object to primitive value
+
+The lesson here is never to use
+
+ return new String("...");
+
+in a Java toString() method. In Java it will be fine; in JavaScript it will also be fine as long as
+that method is never called in JavaScript implicitly in the context of string concatenation.
+
+A note about interning. Consider the following six Java constructions, where we have a == "x";
+
+"xxx"
+"xx" + "x"
+new String("xxx").intern()
+
+new String("xxx")
+"xx" + a.toString()
+"xx" + a
+
+All six of these will return java.lang.String for .getClass().getName().
+However, the first three are String literals, while the last three are String objects.
+Thus:
+ "xxx" == "xxx"
+ "xxx" == "xx" + "x"
+ "xxx" == new String("xxx").intern()
+
+but none of the other three are equivalent to "xxx" or each other:
+
+ "xxx" != new String("xxx")
+ "xxx" != "xx" + a.toString()
+ "xxx" != "xx" + a
+ new String("xxx") != new String("xxx")
+ "xx" + a != new String("xxx")
+
+etc.
+
+As in Java, in SwingJS, all of the following Java assertions pass as true:
+
+ assert("xxx" == "xx" + "x");
+ assert("xxx" == ("xx" + a).intern());
+ assert("xxx" === new String("xxx").intern());
+
+and both of these do as well:
+
+ assert(new String("xxx") != "xxx");
+ assert(new String("xxx") != new String("xxx"));
+
+But the following two fail to assert true:
+
+ assert("xxx" != "xx" + a);
+ assert("xxx" != "xx" + a.toString());
+
+because in JavaScript, both of these right-side expressions evaluate to a simple "interned" string.
+
+In Java, however, these assertions are true because Java implicitly "boxes" String
+concatentaion as a String object, not a literal.
+
+Most of us know not to generally use == with Strings unless they are explicitly interned.
+Where this problem may arise, though, is in IdentityHashMap, which compares objects using
+System.identityHashCode(), which is not the same for different objects or their string literal equivalents.
+
+My recommendation, if you need to use IdentityHashMap with strings is to always use an explicit String.intern()
+for any keys -- unless you really want to keep every string as separate keys even if they are the same sequence,
+in which case, use new String(). This will work in Java and in JavaScript.
+
+Be aware when working with strings that come from SwingJS and are being used by other JavaScript modules
+that those that are String objects will return "object" for the JavaScript typeof operator, not "string".
+
+The easy way to ensure this is no problem is to concatenate strings with "" to force immediate interning:
+
+ var x = aJavaObject.getString() + "";
+
+unless you are certain that the string is being returned is a raw JavaScript string.
+
+Names with "$" and "_"
+----------------------
+
+For the most part, this should be no problem.
+
+Note that the use of $ and _ in Java field names has always been discouraged:
+[https://docs.oracle.com/javase/tutorial/java/nutsandbolts/variables.html]
+
+ You may find some situations where auto-generated names will contain the dollar sign,
+ but your variable names should always avoid using it. A similar convention
+ exists for the underscore character; while it's technically legal to begin your
+ variable's name with "_", this practice is discouraged.
+
+Some impacts of transpiling method names with full qualification:
+
+1) SwingJS will introduce fields that start with $ or _. These will not conflict
+ if the above convention is followed.
+
+2) Fields that have the same Java name as a method are not an issue.
+
+3) Fields that have a Java name with $ that matches a transpiled method name,
+ such as toString$, will need to be refactored in Java to not have that name collision.
+
+4) Fields in a subclass that have the same name as private fields in a superclass
+ represent a name collision, because the superclass method needs to call its private
+ field even if invoked from a subclass. The solution was to modify the subclass field
+ name using one or more prepended $.
+
+5) Use of Class.getDeclaredMethods() reflection will return Method objects having the transpiled
+ name, not the Java name. This could require some j2sNative adjustment
+ to strip the $... parameters from the name if that is needed.
+
+6) Use of Method.getParameterTypes() should work fine, provided class names
+ do not contain "_". This is because the transpiler converts "." to "_" when
+ creating the fully qualified JavaScript name.
+
+
+positive integers do not add to give negative numbers
+-----------------------------------------------------
+
+In Java, the following is true:
+
+ 2000000000 + 2000000000 == -294967296
+
+But in SwingJS, that will be 4000000000. So, for example, the following
+strategy will fail in SwingJS:
+
+ int newLength = lineBuf.length * 2;
+ if (newLength < 0) {
+ newLength = Integer.MAX_VALUE;
+ }
+
+"-1" in JavaScript is not 0xFFFFFFFF.
+
+And one must take care to not compare a negative number with a 32-bit mask. So
+
+(b & 0xFF000000) == 0xFF000000
+
+is true in Java for (int) b = -1, but is false in JavaScript, because 0xFF000000 is 4278190080,
+while (-1 & 0xFF000000) is, strangely enough, -16777216, and, in fact,
+
+(0xFF000000 & 0xFF000000) != 0xFF000000
+
+because -16777216 is not 4278190080.
+
+The fix is that one must compare similar operations:
+
+if ((b & 0xFF000000) == (0xFF000000 & 0xFF000000)) .....
+
+Importantly, the JavaScript Int32Array does behave properly. From
+the Firefox developer console:
+
+>> x = new Int32Array(1)
+<- Int32Array(1) [ 0 ]
+>> x[0] = 4000000000
+<- 4000000000
+>> x[0]
+<- -294967296
+
+Notice that, perhaps unexpectedly, the following two constructs produce
+different results in JavaScript:
+
+x = new Int32Array(1);
+b = x[0] = 4000000000;
+
+(b will be 4000000000)
+
+and
+
+x = new Int32Array(1);
+x[0] = 4000000000;
+b = x[0];
+
+(b will be -294967296)
+
+
+SwingJS leverages array typing to handle all byte and short arithmetic so as
+to ensure that any byte or short operation in JavaScript does give the same
+result in Java. The design decision to not also do this with integer math was
+a trade-off between performance and handling edge cases.
+
+
+ArrayIndexOutOfBounds
+---------------------
+
+You cannot implicitly throw an ArrayIndexOutOfBoundsException in JavaScript.
+JavaScript will simply return "undefined", not throw an Exception. So:
+
+boolean notAGoodIdeaIsOutOfBounds(String[] sa, int i) {
+ try {
+ return (sa[i] == sa[i]);
+ } catch (ArrayIndexOutOfBoundsException e) {
+ return false;
+ }
+}
+
+will work in Java but not in JavaScript. Code should not depend upon this sort
+of trap anyway, if you ask me.
+
+Throwable vs Error vs Exception
+-------------------------------
+
+True JavaScript errors are trapped as Throwable, whereas you can still trap
+Error and Exception as well. So if you want to be sure to catch any JavaScript
+error, use try{}catch (Throwable t){}, not try{}catch (Exception e){}.
+
+j
+ava.awt.Color
+--------------
+
+ColorSpace: only "support" CS_sRGB.
+
+ TODO -- any volunteers??
+
+
+javax.swing.JFileDialog
+-----------------------
+
+HTML5 cannot expose a file reading directory structure. But you certainly
+can still do file reading and writing. It just works a little differently.
+It's a simple modification:
+
+ b = new JButton("FileOpenDialog");
+ b.addActionListener(new ActionListener() {
+
+ @Override
+ public void actionPerformed(ActionEvent e) {
+ JFileChooser fc = new JFileChooser();
+ Test_Dialog.this.onDialogReturn(fc.showOpenDialog(Test_Dialog.this));
+ // Java will wait until the dialog is closed, then enter the onDialogReturn method.
+ // JavaScript will exit with NaN immediately, and then call back with its actual value
+ // asynchronously.
+ }
+
+ });
+
+ public void onDialogReturn(int value) {
+ if (value != Math.floor(value))
+ return; // in JavaScript, this will be NaN, indicating the dialog has been opened
+ // If we are here, the dialog has closed, in both Java and JavaScript.
+ System.out.println("int value is " + value);
+ }
+
+
+ @Override
+ public void propertyChange(PropertyChangeEvent event) {
+ Object val = event.getNewValue();
+ String name = event.getPropertyName();
+ System.out.println(name);
+ switch (event.getSource().getClass().getName()) {
+ case "javax.swing.JOptionPane":
+ switch (name) {
+ case "inputValue":
+ onDialogReturn(val);
+ return;
+ case "value":
+ if (val instanceof Integer)
+ onDialogReturn(((Integer) val).intValue());
+ else
+ onDialogReturn(val);
+ return;
+ }
+ break;
+ case "javax.swing.ColorChooserDialog":
+ switch (name) {
+ case "SelectedColor":
+ onDialogReturn(val);
+ return;
+ }
+ break;
+ case "javax.swing.JFileChooser":
+ switch (name) {
+ case "SelectedFile":
+ File file = (File) val;
+ byte[] array = (val == null ? null : /** @j2sNative file.秘bytes || */
+ null);
+ onDialogReturn("fileName is '" + file.getName() + "'\n\n" + new String(array));
+ return;
+ }
+ break;
+ }
+ System.out.println(
+ event.getSource().getClass().getName() + " " + event.getPropertyName() + ": " + event.getNewValue());
+ }
+
+
+Developers are encouraged to create a separate class that handles general calls to JFileDialog.
+An example class can be found in the SwingJS distribution as
+
+/sources/net.sf.j2s.java.core/src/javajs/async/AsyncFileChooser.java.
+
+
+javax.swing.JOptionPane dialogs
+-------------------------------
+
+For this action to work, the parentComponent must implement
+propertyChangeListener, and any call to JOptionPanel should allow for
+an asynchronous response, meaning that there is no actionable code following the
+call to the dialog opening.
+
+In addition, for compatibility with the Java version, implementation should
+wrap the call to getConfirmDialog or getOptionDialog in a method call to
+handle the Java:
+
+onDialogReturn(JOptionPane.showConfirmDialog(parentFrame,
+messageOrMessagePanel, "title", JOptionPane.OK_CANCEL_OPTION));
+
+Then parentFrame.propertyChange(event) should also call onDialogReturn.
+
+This will then work in both Java and JavaScript.
+
+Note that there is an int and an Object version of onDialogReturn().
+
+
+In JavaScript:
+
+The initial return from JOptionPane.showConfirmDialog and showMessageDialog
+will be (SwingJS) JDialog.ASYNCHRONOUS_INTEGER (NaN), testable as an impossible
+Java int value using ret != -(-ret) if the parent implements PropertyChangeListener, or -1
+(CLOSE_OPTION) if not.
+
+For showOptionDialog (which returns Object) or showInputDialog (which returns
+String), the initial return will be (SwingJS) JDialog.ASYNCHRONOUS_OBJECT, testable as
+((Object) ret) instanceof javax.swing.plaf.UIResource if the parent implements
+PropertyChangeListeneer, or null if not.
+
+The second return will be the desired return.
+
+In Java:
+
+The initial return will be the one and only modal final return.
+
+
+
+For full compatibility, The calling method must not continue beyond this
+call.
+
+All of the standard Java events associated with Components are also
+available.
+
+Certain fall back mechanisms are possible, where onReturn does not exist, but
+only for the following cases:
+
+
+For showMessageDialog, for WARNING_MESSAGE and ERROR_MESSAGE, a simple
+JavaScript alert() is used, returning 0 (OK_OPTION) or -1 (CLOSED_OPTION).
+
+For showInputDialog, if the message is a string, a simple JavaScript prompt()
+with input box is used, returning the entered string or null.
+
+For showConfirmDialog, a simple JavaScript confirm() is used, in which case:
+
+for YES_NO_OPTION: YES_OPTION or NO_OPTION
+
+for YES_NO_CANCEL_OPTION: YES_OPTION or CANCEL_OPTION
+
+for OK_CANCEL_OPTION or any other: OK_OPTION or CANCEL_OPTION
+
+Note that you should implement a response for CLOSED_OPTION for
+showConfirmDialog. For other dialogs, a null return indicates the dialog was
+closed, just as for Java.
+
+Developers are encouraged to create a separate class that handles general calls.
+An example class can be found in the SwingJS distribution as src/javajs/async/AsyncDialog.java.
+Very simple modifications to the Java allows asynchronous operation using AsyncDialog. Here
+is a simple "do you want to close this frame" example, where you can see that what we have
+done is to set the reply into an ActionListener that is defined in the constructor of
+the AsyncDisplay object:
+
+// Original:
+//
+// private void promptQuit() {
+// int sel = JOptionPane.showConfirmDialog(null, PROMPT_EXIT, NAME, JOptionPane.YES_NO_OPTION);
+// switch (sel) {
+// case JOptionPane.YES_OPTION:
+// resultsTab.clean();
+// seqs.dispose();
+// if (fromMain) {
+// System.exit(0);
+// }
+// break;
+// }
+// }
+
+ private void promptQuitAsync() {
+ new AsyncDialog(new ActionListener() {
+
+ @Override
+ public void actionPerformed(ActionEvent e) {
+ int sel = ((AsyncDialog)e.getSource()).getOption();
+ switch (sel) {
+ case JOptionPane.YES_OPTION:
+ resultsTab.clean();
+ seqs.dispose();
+ if (fromMain) {
+ System.exit(0);
+ }
+ break;
+ }
+ }}).showConfirmDialog(null, PROMPT_EXIT, NAME, JOptionPane.YES_NO_OPTION);
+ }
+
+Very simple!
+
+
+native methods
+--------------
+
+The J2S compiler ignores all static native method declarations.
+Anything of this nature needs to be implemented in JavaScript if it is needed,
+using j2sNative blocks:
+
+/**
+ * @j2sNative
+ *
+ * var putYourJavaScriptCodeHere
+ *
+ */
+
+ Note that if you follow that directly with a {...} block, then
+ the javadoc code will run in JavaScript, and the {...} code will run in Java.
+
+
+key Focus
+---------
+
+As of June, 2019, the keyboard focus manager is fully implemented.
+The one catch is that JTextPane and JTextArea, which already consume
+VK_TAB in Java, cannot use CTRL-TAB to continue a tabbing cycle around
+the components in a window. Instead, CTRL-TAB is absorbed by the browser.
+
+
+LookAndFeel and UI Classes
+--------------------------
+
+SwingJS implements the native browser look and feel as swingjs.plaf.HTML5LookAndFeel.
+There are small differences between all look and feels -- MacOS, Windows, SwingJS.
+
+Expert developers know how to coerce changes in the UI by subclassing the UI for a
+component. This probably will not work in SwingJS.
+
+Note that LookAndFeel in Java usually determines canvas size in a Frame because
+different operating systems (Mac OS vs Windows vs HTML5) will have
+different edge sizes on their frames. If you want to ensure a component size,
+use getContentPane().setPreferredSize().
+
+
+System.exit(0) does not stop all processes
+------------------------------------------
+
+Although System.ext(int) has been implemented in JavaScript, it just closes the
+frames, stops all pending javax.swing.Timer objects in the queue, and runs any
+threads added using Runtime.getRuntime().addShutdownHook(Thread).
+It may not stop all "threads." So don't rely on that.
+Applications are responsible for shutting down prior to executing System.exit(0).
+
+
+myClass.getField not implemented
+--------------------------------
+
+java.lang.reflect.Field is implemented minimally. It is not
+certain that Field.getDeclaringClass() will work. If you just want a
+value of a field, you can do this:
+
+/**
+ *@j2sNative
+ *
+ * return myClass[name]
+ */
+
+But that is not a java.lang.reflection.Field object.
+
+
+"window" and other reserved JavaScript names
+--------------------------------------------
+
+No reserved top-level JavaScript name is allowed for a package name. So, for example,
+one must rename packages such as "window" or "document" to names such as "win" or "doc".
+
+reserved field and method names
+-------------------------------
+
+In order to minimize the chance of added SwingJS field and method names colliding with ones
+developers might use in subclassing Java classes, we have added U+79D8 (first character of Mandarin
+"secret") to the characters already disrecommended by Java documentation ("$" and "_"). The only problem
+would be if you use that character followed by certain English words in certain classes. For example
+\u79D8canvas for JComponents (in java.awt.JSComponent) and \u79D8byte (in java.io.File).
+
+qualified field and method names
+--------------------------------
+
+Method names in SwingJS are fully qualified, meaning two methods with the same Java name but different
+parameters, such as write(int) and write(double), must not have the same name in JavaScript. (In this
+case, we will have write$I and write$D.) However, in certain cases it may be desirable to leave the
+method names unqualified. In particular, when an interface actually represents a JavaScript object,
+the transpiler can leave a method name unqualified. The default situation for this is a class name
+includes ".api.js" (case-sensitive). This means that any method in any class in a package js within
+a package api, or any private interface js that has an outer interface api, will have all-unqualified
+methods. An example of this is swingjs.plaf.JSComboPopupList, which needs to communicate with a jQuery
+object directly using the following interface:
+
+ private interface api {
+
+ interface js extends JQueryObject {
+
+ abstract js j2sCB(Object options);
+
+ abstract Object[] j2sCB(String method);
+
+ abstract Object[] j2sCB(String method, Object o);
+
+ abstract Object[] j2sCB(String method, int i);
+
+ abstract int j2sCB(String OPTION, String name);
+
+ }
+ }
+
+Notice that all these variants of j2sCB() will call the same method in JavaScript by design.
+
+
+missing Math methods
+--------------------
+
+java.lang.Math is worked out, but some methods are missing, either because they
+involve long integer value that are inaccessible in JavaScript, or because I just
+didn't implement them. This is a result of continued Java development.
+It is easy enough to add these methods if you have the source. They go into j2sClazz.js,
+which is combined with other initial libraries into swingjs2.js by build_site.xml
+
+
+Component.getGraphics(), Graphics.dispose()
+-------------------------------------------
+
+Use of component.getGraphics() is discouraged in Java and in SwingJS.
+Specifically in SwingJS, any call to component.getGraphics() or
+BufferedImage.createGraphics() or Graphics.create(...) should be matched with graphics.dispose(),
+particularly when it is called outside the context of a paint(Graphics)
+call from the system.
+
+If you see your graphics scrolling down the page with each repaint,
+look for where you have used Component.getGraphics() and not Graphics.dispose().
+For example, this will definitely NOT work in SwingJS:
+
+ this.paint(getGraphics())
+
+and really should not work in Java, either, as it is technically a resource memory leak.
+
+Instead, if you really do not want to use repaint(), use this:
+
+ Graphics g = getGraphics();
+ paint(g);
+ g.dispose();
+
+
+
+Graphics.setClip()
+------------------
+
+The HTML5 canvas.clip() method is permanent. You can only reset the clip using
+save/restore. This is different from Java, where you can temporarily change it using
+
+ Shape oldClip = Graphics.getClip();
+ Graphics.setClip(newClip);
+ ...
+ Graphics.setClip(oldClip);
+
+If you need to do something like this, you must schedule the paints
+to not have overlapping clip needs.
+
+
+MAJOR ISSUES--for Bob and Udo within SwingJS
+============================================
+
+fonts
+-----
+
+Fonts and FontMetrics will all be handled in JavaScript. Font matching will
+not be exact, and composite (drawn) fonts will not be supported.
+
+SwingJS handles calls such as font.getFontMetrics(g).stringWidth("xxx") by
+creating a <div> containing that text, placing it in an obscure location on
+the page, and reading div.getBoundingClientRect(). This is a VERY precise
+value, but can be a pixel or two off from what Java reports for the same font.
+
+
+OS-dependent classes
+--------------------
+
+Static classes such as:
+
+ java.awt.Toolkit
+ java.awt.GraphicsEnvironment
+
+
+which are created using Class.forName are implemented using classes in the swingjs package.
+
+AWTAccessor is not implemented.
+
+
+AWT component peers and component "ui" user interfaces
+------------------------------------------------------
+
+ComponentPeer is a class that represents a native AWT component.
+Components with such peers are called "heavy-weight" components.
+They are expected to do the dirty work of graphics drawing.
+
+Java Swing implements peers only for JApplet, JDialog, JFrame, and JWindow.
+References to such objects have been removed, but clearly there must be
+some connection to similar DOM objects, even for "light-weight" components.
+
+
+
+MAJOR ISSUES--to be resolved by implementers
+============================================
+
+fonts
+-----
+
+Glyph/composite/outline fonts are not supported.
+
+
+
+threads
+-------
+
+Thread locking and synchronization are not relevant to JavaScript.
+Thus, anything requiring "notify.." or "waitFor.." could be a serious issue.
+
+All threading must be "faked" in JavaScript. Specifically not available is:
+
+ Thread.sleep()
+
+javax.swing.AbstractButton#doClick(pressTime) will not work, as it requires Thread.sleep();
+
+However, java.lang.Thread itself is implemented and used extensively.
+
+Methods thread.start() and thread.run() both work fine.
+
+For simple applications that use Thread.sleep() just to have a delay, as in a frame rate, for
+example, one can use javax.swing.Timer instead. That is fully implemented.
+
+Likewise, java.util.Timer can be replaced with no loss of performance with javax.Swing.Timer.
+Note that java.util.TimerTask is implemented, but it can also be replaced by an implementation of Runnable.
+
+task = new TimerTask(){....};
+t = new java.util.Timer();
+t.schedule(task, 0, 1);
+
+becomes
+
+task = new TimerTask(){....}; // or task = new Runnable() {...}
+t = new javax.swing.Timer(1, new ActionListener() {
+ @Override
+ public void actionPerformed(ActionEvent e) {
+ task.run();
+ }
+};
+t.setInitialDelay(0); // not particularly necessary
+t.start();
+
+In addition, SwingJS provides swingjs.JSThread, which can be subclassed
+if desired. This class allows simple
+
+ while(!interrupted()){
+ wait()
+ ...
+ }
+
+action through an asynchronous function run1(mode). For example:
+
+ protected void run1(int mode) {
+ try {
+ while (true)
+ switch (mode) {
+ case INIT:
+ // once-through stuff here
+ mode = LOOP;
+ break;
+ case LOOP:
+ if (!doDispatch || isInterrupted()) {
+ mode = DONE;
+ } else {
+ Runnable r = new Runnable() {
+ public void run() {
+ // put the loop code here
+ }
+ };
+ dispatchAndReturn(r);
+ if (isJS)
+ return;
+ }
+ break;
+ // add more cases as needed
+ case DONE:
+ // finish up here
+ if (isInterrupted())
+ return;
+ // or here
+ break;
+ }
+ } finally {
+ // stuff here to be executed after each loop in JS or at the end in Java
+ }
+ }
+
+image loading
+-------------
+- All image loading in SwingJS is synchronous. A MediaTracker call will immediately return "complete".
+ However, it still may take one system clock tick to fully load images. Thus, it is recommended that
+ images be preloaded in the static block of the applet if it is necessary that they be available in init().
+ This is only an issue if you are trying to access the pixel buffer of the image in JavaScript.
+
+- Applet.getImage(path, name) will return null if the image does not exist.
+
+- BufferedImage: only "support" imageType RGB and ARGB
+
+ -BH: This is a temporary edit, just to get us started. Certainly GRAY will be needed
+
+
+BigInteger and BigDecimal
+-------------------------
+
+java.math.BigInteger is fully supported; java.math.BigDecimal is roughed
+in and not fully tested (07/2019).
+
+Both classes present significant issues for JavaScript, as they are based in
+Java's 64-bit long for all their operations. Here is the JavaDoc note I added
+to BigInteger:
+
+ * SwingJS note: Because of the limitations of JavaScript with regard
+ * to long-integer bit storage as a double, this implementation drops
+ * the integer storage bit length to 24, giving 48 for long and leaving
+ * the last 16 bits clear for the exponent of the double number. This should
+ * not affect performance significantly. It does increase the storage
+ * size by about 33%. By bringing an "int" to 3 bytes, we can easily construct
+ * and use byte[] data intended for the original BitSet.
+
+"Easily" may be a bit strong there. This was a serious challenge.
+
+BigDecimal seems to run normally, but in order to do that, my hack involves
+reducing the size of an integer that is allowed to be stored as such and not
+in byte[] as a BigInteger. I'm sure there is a performance hit, but it does work.
+
+no format internationalization
+------------------------------
+
+For now, just en for number and date formatters
+
+no winding rules
+----------------
+
+ When filling a graphic, only nonzero winding rule is implemented in HTML5 Canvas2D.
+
+
+
+text-related field implementation
+---------------------------------
+
+Text fields are:
+
+JTextField (JavaScript <input type="text">)
+JTextArea (JavaScript <textarea>)
+JTextPane (JavaScript <div>)
+JEditorPane (JavaScript <div>)
+
+For the initial implementation, we don't implement infinite undo/redo, and the abstract
+document model is much less elaborate. Only PlainDocument (in the form of JSPlainDocument)
+is implemented. The Document returned by JTextField.getDocument() is a javax.swing.text.Document.
+
+All scrolling is handled by HTML5. javax.swing.AutoScroller is not implemented.
+public static methods .stop, .isRunning, .processMouseDragged require true Java threading
+and so are not implmented. javax.swing.text.View and its subclasses are not implemented.
+
+The JS document model does not allow two text fields to address the same underlying document.
+
+JavaScript is slightly different from Java in that the field value is changed asynchronously after
+the keypressed event, so Java actions that are keyed to KEY_PRESSED may not pick up the new
+key value even after SwingUtilities.invokeLater() is called. Thus, key pressed actions may need
+to be recorded after a key released event instead.
+
+Formatter/Regex limitations
+---------------------------
+
+Some browsers cannot process Regex "look-behind" process such as (?<=\W)
+java.util.regex.Matcher and Pattern use JavaScript's RegExp object rather than
+the native Java object. These are not identical. Only flags /igm are supported.
+Matcher.start(groupID) is not supported.
+
+java.util.Formatter will function correctly for all standard %... patterns.
+
+integer 1/0 == Infinity
+-----------------------
+
+1/0 in Java throws "java.lang.ArithmeticException: / by zero", but in JavaScript is just Infinity.
+
+
+
+Summary
+-------
+
+These are all the known limitations of SwingJS. We have not found any of these limitations
+to be show-stoppers. The primary issue for newcomers to SwingJS is having the source code.
+You must check that source code for all your library jar files is available or, if you
+choose, you will need to decompile those classes. We have used decompilation on some projects,
+and it works just fine. So, technically, all we really need are JAR/class files. But the
+source is by far superior. It's generally prettier, and it has the license information that
+may or may not be present with the JAR or class files. Use class files at your own risk.
+
+Bob Hanson
+2019.08.16
+
+
+Additional Issues
+-----------------
+
+Annotation is working for classes, methods, and fields (12/22/19). Method reflection, however,
+is limited. Interfaces do not expose their methods, as the transpiler does not actually transpile
+the interfaces themselves. And method reflection only includes annotated methods.
+
+java.util.concurrent is not fully elaborated. This package is rewritten to not actually use the
+memory handling capabilities of concurrency, which JavaScript does not have access to.
+
+System.getProperties() just returns a minimal set of properties.
+
+
-20200408084722
+20201219150605
--- /dev/null
+This is sources/net.sf.j2s.java.core/dist/DEV_NOTES.txt
+
+_j2sclasslist.txt
+
+the list of .js files concatenated into coreswingjs.js and minified to coreswingjs.z.js
+
+
+SwingJS-site.zip
+
+the full site directory for SwingJS including all files not in the test/ directory.
--- /dev/null
+This directory holds 3.2.9 transpiler and runtime tagged previous
+to the transpiler fix for boxed number direct manipulation:
+
+Long L = Long.valueOf(3);
+L++;
+L /= 2;
+L += 10;
+L = L / 5;
+
+etc.
+
+These assignments are not made properly and fail.
+
+In addition, this runtime does not handle Long properly and also had an issue with Short.equals(Object)
+
+just saving this and will probably delete it.
+
--- /dev/null
+java/applet/Applet.js
+java/applet/AppletContext.js
+java/applet/AppletStub.js
+java/applet/JSApplet.js
+java/awt/ActiveEvent.js
+java/awt/Adjustable.js
+java/awt/AWTEvent.js
+java/awt/AWTEventMulticaster.js
+java/awt/AWTKeyStroke.js
+java/awt/BasicStroke.js
+java/awt/BorderLayout.js
+java/awt/Button.js
+java/awt/Color.js
+java/awt/color/ColorSpace.js
+java/awt/Component.js
+java/awt/ComponentOrientation.js
+java/awt/ContainerOrderFocusTraversalPolicy.js
+java/awt/Container.js
+java/awt/Cursor.js
+java/awt/DefaultFocusTraversalPolicy.js
+java/awt/DefaultKeyboardFocusManager.js
+java/awt/Dialog.js
+java/awt/Dimension.js
+java/awt/dnd/peer/DropTargetPeer.js
+java/awt/event/ActionListener.js
+java/awt/event/AdjustmentEvent.js
+java/awt/event/AdjustmentListener.js
+java/awt/event/AWTEventListener.js
+java/awt/event/ComponentAdapter.js
+java/awt/event/ComponentEvent.js
+java/awt/event/ComponentListener.js
+java/awt/event/ContainerListener.js
+java/awt/event/FocusEvent.js
+java/awt/event/FocusListener.js
+java/awt/event/HierarchyBoundsListener.js
+java/awt/event/HierarchyListener.js
+java/awt/event/InputEvent.js
+java/awt/event/InputMethodListener.js
+java/awt/event/InvocationEvent.js
+java/awt/event/ItemEvent.js
+java/awt/event/ItemListener.js
+java/awt/event/KeyListener.js
+java/awt/event/MouseEvent.js
+java/awt/event/MouseListener.js
+java/awt/event/MouseMotionListener.js
+java/awt/event/MouseWheelListener.js
+java/awt/event/TextListener.js
+java/awt/event/WindowAdapter.js
+java/awt/event/WindowEvent.js
+java/awt/event/WindowFocusListener.js
+java/awt/event/WindowListener.js
+java/awt/event/WindowStateListener.js
+java/awt/EventDispatchThread.js
+java/awt/EventFilter.js
+java/awt/EventQueue.js
+java/awt/EventQueueItem.js
+java/awt/FlowLayout.js
+java/awt/FocusTraversalPolicy.js
+java/awt/Font.js
+java/awt/font/FontRenderContext.js
+java/awt/FontMetrics.js
+java/awt/Frame.js
+java/awt/geom/AffineTransform.js
+java/awt/geom/Dimension2D.js
+java/awt/geom/Path2D.js
+java/awt/geom/PathIterator.js
+java/awt/geom/Point2D.js
+java/awt/geom/Rectangle2D.js
+java/awt/geom/RectangularShape.js
+java/awt/geom/RectIterator.js
+java/awt/GraphicsCallback.js
+java/awt/GraphicsConfiguration.js
+java/awt/GraphicsDevice.js
+java/awt/GraphicsEnvironment.js
+java/awt/Image.js
+java/awt/image/ImageObserver.js
+java/awt/Insets.js
+java/awt/ItemSelectable.js
+java/awt/JSComponent.js
+java/awt/JSDialog.js
+java/awt/JSFrame.js
+java/awt/JSPanel.js
+java/awt/KeyboardFocusManager.js
+java/awt/KeyEventDispatcher.js
+java/awt/KeyEventPostProcessor.js
+java/awt/Label.js
+java/awt/LayoutManager.js
+java/awt/LayoutManager2.js
+java/awt/LightweightDispatcher.js
+java/awt/Paint.js
+java/awt/Panel.js
+java/awt/peer/ComponentPeer.js
+java/awt/peer/ContainerPeer.js
+java/awt/peer/FramePeer.js
+java/awt/peer/KeyboardFocusManagerPeer.js
+java/awt/peer/LightweightPeer.js
+java/awt/peer/WindowPeer.js
+java/awt/Point.js
+java/awt/Queue.js
+java/awt/Rectangle.js
+java/awt/RenderingHints.js
+java/awt/Scrollbar.js
+java/awt/ScrollPane.js
+java/awt/Shape.js
+java/awt/Stroke.js
+java/awt/TextArea.js
+java/awt/TextComponent.js
+java/awt/TextField.js
+java/awt/Toolkit.js
+java/awt/Transparency.js
+java/awt/Window.js
+java/beans/ChangeListenerMap.js
+java/beans/PropertyChangeEvent.js
+java/beans/PropertyChangeListener.js
+java/beans/PropertyChangeSupport.js
+java/lang/AbstractStringBuilder.js
+java/lang/Class.js
+java/lang/Enum.js
+java/lang/Iterable.js
+java/lang/reflect/Constructor.js
+java/lang/reflect/Method.js
+java/lang/StringBuffer.js
+java/lang/StringBuilder.js
+java/lang/Thread.js
+java/lang/ThreadGroup.js
+java/math/RoundingMode.js
+java/net/URL.js
+java/net/URLStreamHandlerFactory.js
+java/net/HttpURLConnection.js
+java/net/URLStreamHandler.js
+javax/net/ssl/HttpsUrlConnection.js
+java/text/CharacterIterator.js
+java/text/DecimalFormat.js
+java/text/DecimalFormatSymbols.js
+java/text/DigitList.js
+java/text/FieldPosition.js
+java/text/Format.js
+java/text/NumberFormat.js
+java/util/AbstractCollection.js
+java/util/AbstractList.js
+java/util/AbstractMap.js
+java/util/AbstractSequentialList.js
+java/util/AbstractSet.js
+java/util/ArrayList.js
+java/util/Arrays.js
+java/util/Collection.js
+java/util/Collections.js
+java/util/Comparator.js
+java/util/Deque.js
+java/util/Dictionary.js
+java/util/Enumeration.js
+java/util/EventListener.js
+java/util/EventObject.js
+java/util/HashMap.js
+java/util/HashSet.js
+java/util/Hashtable.js
+java/util/IdentityHashMap.js
+java/util/Iterator.js
+java/util/LinkedHashMap.js
+java/util/LinkedList.js
+java/util/List.js
+java/util/ListResourceBundle.js
+java/util/Locale.js
+java/util/Map.js
+java/util/Objects.js
+java/util/Queue.js
+java/util/Random.js
+java/util/RandomAccess.js
+java/util/ResourceBundle.js
+java/util/Set.js
+java/util/TimSort.js
+java/util/Vector.js
+javajs/api/JSFunction.js
+javajs/util/AjaxURLConnection.js
+javajs/util/AjaxURLStreamHandlerFactory.js
+javajs/util/AU.js
+javajs/util/JSThread.js
+javajs/util/Lst.js
+javajs/util/PT.js
+javajs/util/Rdr.js
+javajs/util/SB.js
+javax/swing/AbstractAction.js
+javax/swing/AbstractButton.js
+javax/swing/AbstractListModel.js
+javax/swing/Action.js
+javax/swing/ActionMap.js
+javax/swing/AncestorNotifier.js
+javax/swing/ArrayTable.js
+javax/swing/border/AbstractBorder.js
+javax/swing/border/BevelBorder.js
+javax/swing/border/Border.js
+javax/swing/border/CompoundBorder.js
+javax/swing/border/EmptyBorder.js
+javax/swing/border/EtchedBorder.js
+javax/swing/border/LineBorder.js
+javax/swing/border/TitledBorder.js
+javax/swing/BorderFactory.js
+javax/swing/BoundedRangeModel.js
+javax/swing/BoxLayout.js
+javax/swing/ButtonGroup.js
+javax/swing/ButtonModel.js
+javax/swing/ClientPropertyKey.js
+javax/swing/ComboBoxModel.js
+javax/swing/DefaultBoundedRangeModel.js
+javax/swing/DefaultButtonModel.js
+javax/swing/DefaultComboBoxModel.js
+javax/swing/DefaultSingleSelectionModel.js
+javax/swing/DropMode.js
+javax/swing/event/AncestorEvent.js
+javax/swing/event/AncestorListener.js
+javax/swing/event/CaretEvent.js
+javax/swing/event/CaretListener.js
+javax/swing/event/ChangeEvent.js
+javax/swing/event/ChangeListener.js
+javax/swing/event/DocumentEvent.js
+javax/swing/event/DocumentListener.js
+javax/swing/event/EventListenerList.js
+javax/swing/event/ListDataEvent.js
+javax/swing/event/ListDataListener.js
+javax/swing/event/UndoableEditEvent.js
+javax/swing/event/UndoableEditListener.js
+javax/swing/FocusManager.js
+javax/swing/InternalFrameFocusTraversalPolicy.js
+javax/swing/LayoutComparator.js
+javax/swing/LayoutFocusTraversalPolicy.js
+javax/swing/SortingFocusTraversalPolicy.js
+javax/swing/SwingContainerOrderFocusTraversalPolicy.js
+javax/swing/SwingDefaultFocusTraversalPolicy.js
+javax/swing/Icon.js
+javax/swing/ImageIcon.js
+javax/swing/InputMap.js
+javax/swing/JApplet.js
+javax/swing/JButton.js
+javax/swing/JCheckBox.js
+javax/swing/JCheckBoxMenuItem.js
+javax/swing/JComboBox.js
+javax/swing/JComponent.js
+javax/swing/JFrame.js
+javax/swing/JLabel.js
+javax/swing/JLayeredPane.js
+javax/swing/JMenu.js
+javax/swing/JMenuBar.js
+javax/swing/JMenuItem.js
+javax/swing/JPanel.js
+javax/swing/JPopupMenu.js
+javax/swing/JRadioButtonMenuItem.js
+javax/swing/JRootPane.js
+javax/swing/JScrollBar.js
+javax/swing/JScrollPane.js
+javax/swing/JSeparator.js
+javax/swing/JTextArea.js
+javax/swing/JTextField.js
+javax/swing/JToggleButton.js
+javax/swing/JViewport.js
+javax/swing/KeyboardManager.js
+javax/swing/KeyStroke.js
+javax/swing/ListModel.js
+javax/swing/LookAndFeel.js
+javax/swing/MenuElement.js
+javax/swing/MutableComboBoxModel.js
+javax/swing/plaf/ActionMapUIResource.js
+javax/swing/plaf/basic/BasicBorders.js
+javax/swing/plaf/BorderUIResource.js
+javax/swing/plaf/ColorUIResource.js
+javax/swing/plaf/ComponentUI.js
+javax/swing/plaf/DimensionUIResource.js
+javax/swing/plaf/FontUIResource.js
+javax/swing/plaf/InputMapUIResource.js
+javax/swing/plaf/InsetsUIResource.js
+javax/swing/plaf/UIResource.js
+javax/swing/RepaintManager.js
+javax/swing/RootPaneContainer.js
+javax/swing/Scrollable.js
+javax/swing/ScrollPaneConstants.js
+javax/swing/ScrollPaneLayout.js
+javax/swing/SingleSelectionModel.js
+javax/swing/SizeRequirements.js
+javax/swing/SwingConstants.js
+javax/swing/SwingPaintEventDispatcher.js
+javax/swing/SwingUtilities.js
+javax/swing/text/AbstractDocument.js
+javax/swing/text/AttributeSet.js
+javax/swing/text/Caret.js
+javax/swing/text/DefaultCaret.js
+javax/swing/text/DefaultEditorKit.js
+javax/swing/text/Document.js
+javax/swing/text/EditorKit.js
+javax/swing/text/Element.js
+javax/swing/text/GapContent.js
+javax/swing/text/GapVector.js
+javax/swing/text/JTextComponent.js
+javax/swing/text/MutableAttributeSet.js
+javax/swing/text/PlainDocument.js
+javax/swing/text/PlainView.js
+javax/swing/text/Position.js
+javax/swing/text/Segment.js
+javax/swing/text/SegmentCache.js
+javax/swing/text/SimpleAttributeSet.js
+javax/swing/text/Style.js
+javax/swing/text/StyleConstants.js
+javax/swing/text/StyleContext.js
+javax/swing/text/TabExpander.js
+javax/swing/text/TextAction.js
+javax/swing/text/Utilities.js
+javax/swing/text/View.js
+javax/swing/tree/TreeNode.js
+javax/swing/UIDefaults.js
+javax/swing/UIManager.js
+javax/swing/undo/AbstractUndoableEdit.js
+javax/swing/undo/CompoundEdit.js
+javax/swing/undo/UndoableEdit.js
+javax/swing/ViewportLayout.js
+javax/swing/WindowConstants.js
+sun/awt/AppContext.js
+sun/awt/AWTAutoShutdown.js
+sun/awt/CausedFocusEvent.js
+sun/awt/ComponentFactory.js
+sun/awt/KeyboardFocusManagerPeerProvider.js
+sun/awt/MostRecentKeyValue.js
+sun/awt/MostRecentThreadAppContext.js
+sun/awt/PaintEventDispatcher.js
+sun/awt/PostEventQueue.js
+sun/awt/RequestFocusController.js
+sun/awt/SunToolkit.js
+sun/awt/WindowClosingListener.js
+sun/awt/WindowClosingSupport.js
+sun/awt/image/DataStealer.js
+sun/awt/image/IntegerComponentRaster.js
+sun/awt/image/IntegerInterleavedRaster.js
+sun/awt/image/SunWritableRaster.js
+sun/font/FontDesignMetrics.js
+sun/swing/DefaultLookup.js
+sun/swing/SwingLazyValue.js
+sun/text/resources/FormatData.js
+sun/text/resources/en/FormatData_en.js
+sun/util/resources/LocaleData.js
+sun/util/locale/BaseLocale.js
+sun/util/locale/LocaleUtils.js
+sun/util/locale/provider/LocaleProviderAdapter.js
+sun/util/locale/provider/LocaleDataMetaInfo.js
+swingjs/a2s/A2SContainer.js
+swingjs/a2s/A2SEvent.js
+swingjs/a2s/A2SListener.js
+swingjs/a2s/Applet.js
+swingjs/a2s/Button.js
+swingjs/a2s/Label.js
+swingjs/a2s/Panel.js
+swingjs/a2s/Scrollbar.js
+swingjs/a2s/ScrollPane.js
+swingjs/a2s/TextArea.js
+swingjs/a2s/TextField.js
+swingjs/api/Interface.js
+swingjs/api/js/DOMNode.js
+swingjs/api/js/HTML5CanvasContext2D.js
+swingjs/api/js/JSInterface.js
+swingjs/jquery/JQueryUI.js
+swingjs/JSApp.js
+swingjs/JSAppletThread.js
+swingjs/JSAppletViewer.js
+swingjs/JSFocusPeer.js
+swingjs/JSFontMetrics.js
+swingjs/JSFrameViewer.js
+swingjs/JSGraphics2D.js
+swingjs/JSGraphicsConfiguration.js
+swingjs/JSGraphicsEnvironment.js
+swingjs/JSImage.js
+swingjs/JSImagekit.js
+swingjs/JSMouse.js
+swingjs/JSNullComponentPeer.js
+swingjs/JSScreenDevice.js
+swingjs/JSThreadGroup.js
+swingjs/JSToolkit.js
+swingjs/JSUtil.js
+swingjs/plaf/ButtonListener.js
+swingjs/plaf/DefaultMenuLayout.js
+swingjs/plaf/HTML5LookAndFeel.js
+swingjs/plaf/JSAppletUI.js
+swingjs/plaf/JSButtonUI.js
+swingjs/plaf/JSCheckBoxMenuItemUI.js
+swingjs/plaf/JSCheckBoxUI.js
+swingjs/plaf/JSComboBoxUI.js
+swingjs/plaf/JSComponentUI.js
+swingjs/plaf/JSEventHandler.js
+swingjs/plaf/JSFrameUI.js
+swingjs/plaf/JSGraphicsUtils.js
+swingjs/plaf/JSLabelUI.js
+swingjs/plaf/JSLayeredPaneUI.js
+swingjs/plaf/JSLightweightUI.js
+swingjs/plaf/JSMenuBarUI.js
+swingjs/plaf/JSMenuItemUI.js
+swingjs/plaf/JSMenuUI.js
+swingjs/plaf/JSPanelUI.js
+swingjs/plaf/JSPopupMenuSeparatorUI.js
+swingjs/plaf/JSPopupMenuUI.js
+swingjs/plaf/JSRadioButtonMenuItemUI.js
+swingjs/plaf/JSRadioButtonUI.js
+swingjs/plaf/JSRootPaneUI.js
+swingjs/plaf/JSScrollBarUI.js
+swingjs/plaf/JSScrollPaneUI.js
+swingjs/plaf/JSSeparatorUI.js
+swingjs/plaf/JSSliderUI.js
+swingjs/plaf/JSTextAreaUI.js
+swingjs/plaf/JSTextFieldUI.js
+swingjs/plaf/JSTextUI.js
+swingjs/plaf/JSTextViewUI.js
+swingjs/plaf/JSViewportUI.js
+swingjs/plaf/JSWindowUI.js
+swingjs/plaf/LazyActionMap.js
+swingjs/plaf/Resizer.js
+swingjs/plaf/TextListener.js
+
+
--- /dev/null
+Notes
+=====
+
+---IMPORTANT CHARACTER SET NOTE---
+
+It is critical that all development work in Java2Script
+be done in UTF-8. This means:
+
+- making sure your Eclipse project is set up for UTF-8 (not the Eclipse default?)
+- making sure your server can serve up UTF-8 by default for any browser-loaded files
+- making sure you don't edit a Java2Script class file or one of the site .js files
+ using a non-UTF-8 editor. It may replace non-Latin characters with "?" or garbage.
+- making sure that your web pages are delivered with proper headings indicating HTML5 and UTF-8
+
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="utf-8">
+
+Note that the DOCTYPE tag is critical for some browsers to switch into HTML5 mode. (MSIE?)
+
+
+
+
+In particular, the Mandarin character 秘 (mi; "secret") is used extensively throughout
+the SwingJS class files to distinguish j2s-specific fields and methods that must not
+ever be shadowed or overridden by subclasses. For example, we see in java.lang.Thread.java:
+
+ public static JSThread 秘thisThread;
+
+----------------------------------
+
+
+updated 12/6/2020 -- note about restrictions on long, including BitSet and Scanner
+updated 3/21/2020 -- adds note about HashMap, Hashtable, and HashSet iterator ordering
+updated 3/20/2020 -- adds note about interning, new String("xxx"), and "xxx"
+updated 2/26/2020 -- adds Graphics.setClip issue
+updated 12/22/19 -- additional issues
+updated 11/03/19 -- adds information about File.exists() and points to src/javajs/async
+updated 10/26/19 -- adds information about File.createTempFile()
+updated 8/16/19 -- minor typos and added summary paragraph
+updated 7/19/19 -- clarification that AWT and Swing classes are supported directly
+updated 5/13/19 -- Mandarin U+79D8 reserved character; Missing Math methods; int and long
+updated 5/10/19 -- adds a section on static issues in multi-(duplicate)-applet pages
+updated 1/4/19 -- nio
+updated 9/15/18 -- adds integer 1/0 == Infinity
+updated 7/24/18 -- most classes replaced with https://github.com/frohoff/jdk8u-jdk
+updated 6/5/17 -- reserved package name "window"
+updated 3/11/17 -- myClass.getField
+updated 3/7/17 -- overloading of JSplitPane.setDividerLocation
+updated 3/2/17 -- more indication of classes not implemented (KeyListener)
+
+=============================================================================
+SwingJS and OpenJDK 8+
+=============================================================================
+
+SwingJS implements a wide range of the Java language in JavaScript. The base
+version for this implementation is OpenJDK8. some classes are implemented using
+older source code, and there are some missing methods. For the most part, this is
+no real problem. You can add or modify any java class just be adding it as source
+in your project. Or (preferably) you can contact me, and I can get it into the
+distribution. Or (even more preferably) you can do that via a patch submission.
+
+=================
+DESIGN PHILOSOPHY
+=================
+
+The java2script/SwingJS design goal is to recreate a recognizable, easily debuggable
+equivalent in JavaScript for as much of Java as practical. This means, for example,
+that one can call in JavaScript
+
+ new java.util.Hashtable()
+
+and for all practical purposes it will appear that Java is running.
+
+
+Method and Field Disambiguation
+-------------------------------
+
+SwingJS has no problem with the overloading of methods, for example:
+
+ public void print(int b);
+ public void print(float b);
+
+JavaScript does not allow overloading of methods, and the common practice in
+Java of naming a field the same as a method -- isAllowed and isAllowed() -- is
+not possible in JavaScript. As a result, SwingJS implements "fully-qualified"
+method names using "$" parameter type separation. Thus, these methods in SwingJS
+will be referred to as print$I and print$F. The rules for this encoding are
+relatively simple:
+
+1. The seven primitive types in Java are encoded $I (int), $L (long), $F (float),
+$D (double), $B (byte) $Z (boolean), and $H (short).
+
+2. String and Object are encoded as $S and $O, respectively.
+
+3. "java_lang_" is dropped for all other classes in the java.lang package (as in Java).
+ For example: $StringBuffer, not $java_lang_StringBuffer
+
+4. All other classes are encoded as
+
+ "$" + Class.getName().replace(".","_")
+
+For example, in Java we see:
+
+ public void equals(Object o) {...}
+
+Whereas in SwingJS we have:
+
+ Clazz.newMeth(C$, 'equals$O', function (o) {...}
+
+And
+
+ this.getContentPane().add(bar, "North");
+
+becomes
+
+ this.getContentPane$().add$java_awt_Component$O(bar, "North");
+
+5. Arrays are indicated with appended "A" for each level. So
+
+ setDataVector(Object[][] dataVector, Object[] columnIdentifiers)
+
+becomes
+
+ setDataVector$OAA$OA(dataVector, columnIdentifiers)
+
+(It is recognized that this design does introduce a bit of ambiguity, in that
+ in principal there could be user class named XA and X in the same package,
+ and methods a(X[]) and a(XA) in the same class that cannot be distinguished.
+ The benefit of this simple system, however, triumphed over the unlikelyhood
+ of that scenario.) The transpiler could be set to flag this possibility.
+
+6. Constructors are prepended with "c$". So
+
+ public JLabel(String text) {...}
+
+becomes:
+
+ Clazz.newMeth(C$, 'c$$S', function (text) {...});
+
+Field disambiguation involves prepending. In Java, a class and its subclass
+can both have the same field name, such as
+
+ boolean visible;
+
+When this happens, it is called "shadowing", and though not recommended, Java allows
+it. The Java2Script transpiler will prepend such shadowing fields with "$" so that the
+subclass instance has both "visible" (for use in its methods inherited from its
+superclass) and "$visible" (for its own methods). Thus, we might see in Java:
+
+ this.visible = super.visible;
+
+while in SwingJS we will see:
+
+ this.$visible=this.visible;
+
+since JavaScript does not have the "super" keyword.
+
+
+
+Parameterless methods such as toString() are appended with "$" to become toString$().
+The one exception to this rule is private methods, which are saved in (truly) private
+array in the class (and are not accessible by reflection). Private parameterless
+methods retain their simple Java name, since they cannot conflict with field names.
+
+This renaming of methods has a few consequences, which are discussed more fully below.
+See particularly the section on "qualified field and method names", where it is described
+how you can use packages or classes or interfaces with ".api.js" in them to represent JavaScript
+objects for which all method names are to be left unqualified. Note that it is not
+possible to cherry-pick methods to be unqualified; only full packages, classes or
+interfaces can hold this status.
+
+The swingjs.api.js package in particular contains a number of useful interfaces that
+you can import into your project for JavaScript-specific capabilities.
+
+
+Applet vs. Application
+----------------------
+
+One of the very cool aspects of SwingJS is that it doesn't particularly matter if a browser-based
+Java app is an "applet" or an "application". We don't need JNLP (Java Network Launch Protocol)
+because now we can just start up any Java application in a browser just as easily as any applet.
+The associative array that passes information to the SwingJS applet (information that formerly
+might have been part of the APPLET tag, such as width, height, and codebase, always referred to
+in our writing as "the Info array") allows the option to specify the JApplet/Applet "code"
+class or the application "main" class. Either one will run just fine.
+
+
+Performance
+-----------
+
+Obviously, there are limitations. One is performance, but we have seen reproducible
+performance at 1/6 - 1/3 the speed of Java. Achieving this performance may require
+some refactoring of the Java to make it more efficient in both Java and JavaScript.
+"for" loops need to be more carefully crafted; use of "new" and "instanceof" need to be
+minimized in critical areas. Note that method overloading -- that is, the same method name
+with different parameters, such as read(int) and read(byte) -- is no longer any problem.
+
+
+Threads
+-------
+
+Although there is only a single thread in JavaScript, meaning Thread.wait(), Thread.sleep(int) and
+Thread.notify() cannot be reproduced, we have found that this is not a serious limitation.
+For example, javax.swing.Timer() works perfectly in JavaScript. All it means is that threads
+that use sleep(int) or notify() must be refactored to allow Timer-like callbacks. That is,
+they must allow full exit and re-entry of Thread.run(), not the typical while/sleep motif.
+
+The key is to create a state-based run() that can be exited and re-entered in JavaScript.
+
+
+Static fields
+-------------
+
+Final static primitive "constant" fields (String, boolean, int, etc.) such as
+
+static final int TEST = 3;
+static final String MY_STRING = "my " + "string";
+
+are converted to their primitive form automatically by the Eclipse Java compiler
+and do not appear in the JavaScript by their names.
+
+Other static fields are properties of their class and can be used as expected.
+
+Note, however, that SwingJS runs all "Java" code on a page in a common "jvm"
+(like older versions of Java). So, like the older Java schema, the JavaScript
+equivalents of both applets and applications will share all of their static
+fields and methods. This includes java.lang.System.
+
+Basically, SwingJS implementations of Java run in a browser page-based sandbox
+instead of an applet-specific one.
+
+In general, this is no problem. But if we are to implement pages with
+multiple applets present, we must be sure to only have static references
+that are "final" or specifically meant to be shared in a JavaScript
+environment only (since they will not be shared in Java).
+
+A simple solution, if static non-constant references are needed, is to attach the
+field to Thread.currentThread.threadGroup(), which is an applet-specific reference.
+Be sure, if you do this, that you use explicit setters and getters:
+
+For example,
+
+private static String myvar;
+
+...
+
+public void setMyVar(String x) {
+ ThreadGroup g = Thread.currentThread().threadGroup();
+ /**
+ * @j2sNative g._myvar = x;
+ *
+ */
+ {
+ myvar = x;
+ }
+}
+
+public String getMyVar() {
+ ThreadGroup g = Thread.currentThread().threadGroup();
+ /**
+ * @j2sNative return g._myvar || null;
+ *
+ */
+ {
+ return myvar;
+ }
+}
+
+ in Java will get and set x the same in JavaScript and in Java.
+
+
+A convenient way to do this in general is to supply a singleton class with
+explicitly private-only constructors and then refer to it in Java and in JavaScript
+instead of using static field, referring to myclass.getIntance().xxx instead of
+myclass.xxx in Java (and JavaScript).
+
+This was done extensively in the Jalview project. See jalview.bin.Instance.
+
+
+Helper Packages -- swingjs/ and javajs/
+---------------------------------------
+
+The SwingJS library is the swingjs/ package. There are interfaces that may be of assistance
+in swingjs/api, but other than that, it is not recommended that developers access classes in
+this package. The "public" nature of their methods is really an internal necessity.
+
+In addition to swingjs/, though, there are several useful classes in the javajs/ package
+that could be very useful. This package is a stand-alone package that can be
+cloned in any Java project that also would be great to have in any JavaScript project
+-- SwingJS-related or not. Functionality ranges from reading and writing various file
+formats, including PDF, BMP, PNG, GIF, JPG, JSON, ZIP, and CompoundDocument formats.
+
+A variety of highly efficient three- and four-dimensional point, vector, matrix, and
+quaternion classes are included, as they were developed for JSmol and inherited from that
+project.
+
+Of particular interest should be javajs/async/, which includes
+
+javajs.async.Async
+javajs.async.AsyncColorChooser
+javajs.async.AsyncDialog
+javajs.async.AsyncFileChooser
+
+See javajs.async.Async JavaDoc comments for a full description of
+these useful classes.
+
+
+Modal Dialogs
+-------------
+
+Although true modal dialogs are not possible with only one thread, a functional equivalent --
+asynchronous modal dialogs -- is relatively easy to set up. All the JOptionPane dialogs will
+return PropertyChangeEvents to signal that they have been disposed of and containing the results.
+See below and classes in the javajs.async package.
+
+
+Native calls
+------------
+
+Native calls in Java are calls to operating system methods that are not in Java. JavaScript
+has no access to these, of course, and they must all be replaced by JavaScript equivalents.
+Fortunately, they are not common, and those that are present in Java (for example, in calculating
+checksums in ZIP file creation) are at a low enough level that most developers do not utilize them
+or do not even have access to them. All native calls in Java classes have been replaced by
+Java equivalents.
+
+
+Swing GUI Peers and UIClasses
+-----------------------------
+
+One of the biggest adaptations introduced in SwingJS is in the area of the graphical
+user interface. The issue here is complex but workable. In Java there are two background
+concepts -- the Component "peer" (one per "heavy-weight" component, such as a Frame) and the
+component "uiClass" (one per component, such as JButton or JTextField).
+
+Peers are native objects of the operating system. These are the virtual buttons and text areas
+that the user is interacting with at a very base level. Their events are being passed on to
+Java or the browser by the operating system. UI classes provide a consistent "look and feel"
+for these native objects, rendering them onto the native window canvas and handling all
+user-generated events. They paint the borders, the backgrounds, the highlights, of every
+control you see in Java. There is one-to-one correspondence of Swing classes and UI classes.
+Setting the Look and Feel for a project amounts to selecting the directory from which to draw
+these UI classes. The UI classes can be found in the javax.swing.plaf ("platform look and feel")
+package.
+
+Early on in the development of SwingJS, we decided not to fully reproduce the painfully detailed
+bit-by-bit painting of controls as is done in Java. Instead, we felt it was wiser to utilize the standard
+HTML5 UI capabilities as much as possible, using DIV, and INPUT especially, with extensive use
+of CSS and sometimes jQuery (menus, and sliders, for example). Thus, we have created a new
+set of UIs -- the "HTML5 Look and Feel". These classes can be found in swingjs.plaf. Besides being
+more adaptable, this approach allows far more versatility to SwingJS developers, allowing them
+to modify the GUI to suit their needs if desired.
+
+In SwingJS, since we have no access to native peers except through the browser DOM,
+it seemed logical to merge the peer and UI idea. So instead of having one peer per heavy-weight control and
+one UI class instance for each control type, we just have one UI class instance per control, and
+that UI class instance is what is being referred to when a "peer" is notified.
+
+In some ways this is a throw back to when all of Swing's components were subclasses of
+specific AWT components such as Button and List. These "heavy-weight components" all had their
+own individual native peers and thus automatically took on the look and feel provided by the OS.
+Later Swing versions implemented full look and feel for all peers, leaving only JDialog, JFrame,
+and a few other classes to have native peers. But in SwingJS we have again a 1:1 map of component
+and UI class/peer instance.
+
+The origin of most issues (read "bugs") in relation to the GUI will probably be found in the
+swingjs.plaf JSxxxxUI.java code.
+
+
+Swing-only Components -- no longer an issue
+-------------------------------------------
+
+Swing was introduced into Java well after the Java Abstract Window Toolkit (AWT) was well
+established. As such, its designers chose to allow AWT controls such as Button and List to be used
+alongside their Swing counterparts JButton and JList. Reading the code, it is clear that this
+design choice posed a huge headache for Swing class developers.
+
+For SwingJS, we decided from the beginning NOT to allow this mixed-mode programming and
+instead to require that all components be Swing components.
+
+However, this is no longer an issue. All AWT components in SwingJS are now subclasses of
+javax.swing.JComponent. So far, we have found no problem with this.
+
+
+The a2s Adapter Package
+-----------------------
+
+Originally, we thought that we would restrict ourselves to JApplets only. That is, only
+Swing-based applets. But as we worked, we discovered that there are a lot of great
+applets out there that are pre-Swing pure-AWT java.applet.Applet applets. Our problem was
+that we also wanted it to be possible to quickly adapt these applets to JavaScript as well.
+
+The solution turned out to be simple: Write a package (a2s) that recreates the interface for
+non-Swing components as subclasses of Swing components. Thus, a2s.Button subclasses javax.swing.JButton
+but also accepts all of the methods of java.awt.Button. This works amazingly well, with a few
+special adaptations to the core javax.swing to be "AWT-aware." All AWT components now subclass
+a2s components, which in turn subclass JComponents. So no changes in code are necessary. We have
+successfully transpiled over 500 applets using this strategy. (Kind of surprising, actually, that
+the original Java developers did not see that option. But we have a hindsight advantage here.)
+
+
+Working with Files
+==================
+
+Simple String file names are not optimal for passing information about
+read files within SwingJS applications.
+
+All work with files should either use Path or File objects exclusively.
+These objects, after a file is read or checked for existence, will already
+contain the file byte[] data. Doing something like this:
+
+File f = File("./test.dat");
+boolean isOK = f.exists();
+
+will load f with its byte[] data, if the file exists.
+
+But if after that, we use:
+
+File f2 = new File(f.getAbsolutePath());
+
+f2 will not contain that data. Such copying should be done as:
+
+File f2 = new File(f);
+
+in which case, the byte[] data will be transferred.
+
+
+SwingJS uses the following criteria to determine if File.exists() returns true:
+
+(1) if this File object has been used directly to read data, or
+(2) if reading data using this File object is successful.
+
+Note that you cannot check to see if a file exists before input or if it
+was actually written or if it already exists prior to writing in SwingJS.
+
+Thus, you should check each use of file.exists() carefully, and if necessary, provide a J2sNative
+block that gives an appropriate "OK" message, for example:
+
+(/** @j2sNative 1 ? false : */ outputfile.exits())
+
+or
+
+(/** @j2sNative 1 ? true : */ inputfile.exits())
+
+Temporary files can be created in SwingJS. SwingJS will maintain a pseudo-filesystem for files
+created with File.createTempFile(). This is useful in that closure of writing to a temporary file
+does not generate a pseudo-download to the user's machine.
+
+
+UNIMPLEMENTED CLASSES BY DESIGN
+===============================
+
+The SwingJS implementation of the following classes are present
+in a way that gracefully bypasses their functionality:
+
+accessibility
+security
+serialization
+
+
+
+TODO LIST FOR UNIMPLEMENTED CLASSES
+===================================
+
+JEditorPane (minimal implementation) - DONE 12/2018; some issues still
+JSplitPane - DONE 8/2018
+JTabbedPane - DONE 10/2018
+JTree - done 12/2019
+
+
+MINOR ISSUES--required some rewriting/refactoring by Bob and Udo
+================================================================
+
+Thread.currentThread() == dispatchThread
+
+
+MINOR ISSUES--requiring some rewriting/refactoring outside of SwingJS
+=====================================================================
+
+See below for a full discussion.
+
+Restrictions on long
+Restriction on BitSet and Scanner
+HashMap, Hashtable, and HashSet iterator ordering
+interning, new String("xxx") vs "xxx"
+Names with "$" and "_"
+positive integers do not add to give negative numbers
+ArrayIndexOutOfBounds
+java.awt.Color
+native methods
+javax.swing.JFileDialog
+key focus
+LookAndFeel and UI Classes
+System.exit(0) does not stop all processes
+list cell renderers must be JComponents
+myClass.getField not implemented
+"window" and other reserved JavaScript names
+reserved field and method names
+qualified field and method names
+missing Math methods
+Component.getGraphics(), Graphics.dispose()
+Graphics.setClip()
+
+MAJOR ISSUES--for Bob and Udo within SwingJS
+============================================
+
+fonts
+OS-dependent classes
+AWT component peers
+some aspects of reflection
+
+MAJOR ISSUES--to be resolved by implementers
+============================================
+
+fonts
+threads
+modal dialogs
+image loading
+BigDecimal not fully implemented
+no format internationalization
+no winding rules
+text-related field implementation
+Formatter/Regex limitations
+integer 1/0 == Infinity
+
+========================================================================
+
+DISCUSS
+=======
+
+Table row/col sorter needs checking after removal of java.text.Collator references
+
+I had to move all of SunHints class to RenderingHints, or the
+two classes could not be loaded. Shouldn't be a problem, I think. The sun classes are
+not accessible to developers in Java anyway, since they are generally package private.
+
+==========================================================================
+
+//////////////////////////////////////////////////////////////////////////////
+
+UNIMPLEMENTED CLASSES
+=====================
+
+accessibility
+-------------
+
+All Accessibility handling has been commented out to save the download footprint.
+This removes the need for sun.misc.SharedSecrets as well.
+Nothing says we could not implement accessibility. We just didn't.
+
+
+security
+--------
+
+All JavaScript security is handled by the browser natively.
+Thus, Java security checking is no longer necessary, and
+java.security.AccessController has been simplified to work without
+native security checking.
+
+Note that private methods in a class are REALLY private.
+
+
+serialization
+-------------
+
+All serialization has been removed. It was never very useful for Swing anyway,
+because one needs exactly the same Java version to save and restore serialized objects.
+
+
+keyboard accelerators and mnemonics
+-----------------------------------
+
+This work was completed in the spring of 2019. Note that in a browser, some
+key strokes, particularly CTRL-keys, are not available. Bummer.
+
+
+MINOR ISSUES--required some rewriting/refactoring by Bob and Udo
+================================================================
+
+
+Thread.currentThread() == dispatchThread
+----------------------------------------
+
+changed to JSToolkit.isDispatchThread()
+
+
+MINOR ISSUES--requiring some rewriting/refactoring outside of SwingJS
+=====================================================================
+
+restrictions on long
+--------------------
+
+Java's 64-bit long type is not supported in JavaScript. There is no Int64Array in JavaScript,
+and 0x20000000000000 + 1 evaluates to 0x20000000000000, not 0x20000000000001.
+(Likewise, -0x20000000000000 - 1 is left unchanged.)
+
+The largest "integer" value in JavaScript is 9007199254740991 (9.007199254740991E13, or 0x1FFFFFFFFFFFFFF).
+Effectively, you get to use only 53 bits of the long, not 64. Trying to set a long larger than
+0x1FFFFFFFFFFFFFF or smaller than -0x1FFFFFFFFFFFFFF will result in a NumberFormatException.
+
+The transpiler handles conversion to long the same as Java for all cases other than from double.
+
+For small double values, there is no problem, and, in fact, this is a known trick used to round
+doubles and floats toward zero:
+
+double d;
+d = (long) 3.8;
+assert(d == 3);
+d = (long) -3.8;
+assert(d == -3);
+
+SwingJS will evaluate (long) d as 0 for d > 9007199254740991
+or d < -9007199254740991, same as Java returns for Double.NaN.
+So, in Java we have:
+
+ assert(((long) Double.NaN) == 0);
+ assert(((int) Double.NaN) == 0);
+ assert(((long) Float.NaN) == 0);
+ assert(((int) Float.NaN) == 0);
+
+and also, in JavaScript only, we also have:
+
+ double d = 0x2000000000000L;
+ assert(((long) d) == 0);
+
+
+restrictions on BitSet and Scanner
+----------------------------------
+
+Because of the issue of long being only 53 bits, any time a method returns a long value, considerations must
+be made as to whether this will work in JavaScript. In particular, BitSet and Scanner have issues.
+
+In SwingJS, java.util.BitSet has been implemented as a 32-bit integer-based bitset. This was no problem in
+Java 6, but starting with Java 7, a method was added to BitSet that allows for the extraction of the
+underlying long[] word data. This is not work in JavaScript. Instead, SwingJS java.util.Bitset.toLongArray() will deliver
+32-bit int[] data.
+
+SwingJS Scanner has hasNextLong() and nextLong(), and although it will scan through long numbers,
+Scanner will choke on long numbers greater than the JavaScript 53-bit limit. hasNextLong() will
+return false, and nextLong() will throw an InputMismatchException triggered by the NumberFormatException
+thrown by Long.parseLong().
+
+
+HashMap, Hashtable, and HashSet iterator ordering
+-------------------------------------------------
+
+In Java, iterators for HashMap, Hashtable, and HashSet do not guarantee any particular order.
+From the HashMap documentation for Java 8:
+
+ This class makes no guarantees as to the order of the map; in particular, it does not
+ guarantee that the order will remain constant over time.
+
+Likewise, for HashSet (because it is simply a convenience method for HashMap<Object,PRESENT>:
+
+ [HashSet] makes no guarantees as to the iteration order of the set.
+
+JavaScript's Map object is different. It is basically a LinkedHashMap, so it guarantees iteration
+in order of object addition.
+
+Starting with java2script 3.2.9.v1, these classes use the JavaScript Map object rather than hash codes
+whenever all keys are strictly of JavaScript typeof "string". If any key is introduced that is not a string, the
+implementation falls back to using hash codes, the same as Java.
+
+Note strings created using new String("xxxx") are NOT typeof "string"; they are typeof "object".
+
+The result is significantly faster performance (3-12 x faster) than originally, and up to 3 x faster
+performance in JavaScript than in Java itself. Right. Faster than Java.
+
+The JavaScript Map implementation is implemented UNLESS the constructor used is the one that
+specifies both initial capacity and load factor in their constructor. Thus,
+
+new Hashtable()
+new HashMap()
+new HashMap(16)
+new HashSet()
+
+all use the JavaScript Map. But
+
+new Hashtable(11, 0.75f)
+new HashMap(16, 0.75f)
+new HashSet(16, 0.75f)
+
+do not.
+
+This design allows for opting out of the JavaScript Map use in order to retain the exact behavior of
+iterators in JavaScript as in Java.
+
+
+interning, new String("xxx") vs "xxx"
+-------------------------------------
+
+Note that the following are true in JavaScript:
+
+typeof new String("xxxx") == "object"
+typeof "xxxx" == "string"
+var s = "x";typeof ("xxx" + s) == "string"
+
+There is no equivalence to this behavior in Java, where a String is a String is a String.
+
+Be aware that SwingJS does not always create a JavaScript String object using JavaScript's
+new String(...) constructor. It only does this for Java new String("xxxx") or new String(new String()).
+
+In all other cases, new String(...) (in Java) results in a simple "xxxx" string in JavaScript.
+That is, it will be JavaScript typeof "string", not typeof "object".
+
+The reason for this design is that several classes in the Java core use toString()
+methods that return new String(), and those classes that do that would cause a JavaScript error
+if implicitly stringified if new String() returned a JavaScript String object.
+
+This is fine in JavaScript
+
+test1 = function() { return { toString:function(){ return "OK" } } }
+"testing" + new test1()
+>> "testingOK"
+
+But for whatever reason in JavaScript:
+
+test2 = function() { return { toString:function(){ return new String("OK") } } }
+"testing" + new test2()
+>> Uncaught TypeError: Cannot convert object to primitive value
+
+The lesson here is never to use
+
+ return new String("...");
+
+in a Java toString() method. In Java it will be fine; in JavaScript it will also be fine as long as
+that method is never called in JavaScript implicitly in the context of string concatenation.
+
+A note about interning. Consider the following six Java constructions, where we have a == "x";
+
+"xxx"
+"xx" + "x"
+new String("xxx").intern()
+
+new String("xxx")
+"xx" + a.toString()
+"xx" + a
+
+All six of these will return java.lang.String for .getClass().getName().
+However, the first three are String literals, while the last three are String objects.
+Thus:
+ "xxx" == "xxx"
+ "xxx" == "xx" + "x"
+ "xxx" == new String("xxx").intern()
+
+but none of the other three are equivalent to "xxx" or each other:
+
+ "xxx" != new String("xxx")
+ "xxx" != "xx" + a.toString()
+ "xxx" != "xx" + a
+ new String("xxx") != new String("xxx")
+ "xx" + a != new String("xxx")
+
+etc.
+
+As in Java, in SwingJS, all of the following Java assertions pass as true:
+
+ assert("xxx" == "xx" + "x");
+ assert("xxx" == ("xx" + a).intern());
+ assert("xxx" === new String("xxx").intern());
+
+and both of these do as well:
+
+ assert(new String("xxx") != "xxx");
+ assert(new String("xxx") != new String("xxx"));
+
+But the following two fail to assert true:
+
+ assert("xxx" != "xx" + a);
+ assert("xxx" != "xx" + a.toString());
+
+because in JavaScript, both of these right-side expressions evaluate to a simple "interned" string.
+
+In Java, however, these assertions are true because Java implicitly "boxes" String
+concatentaion as a String object, not a literal.
+
+Most of us know not to generally use == with Strings unless they are explicitly interned.
+Where this problem may arise, though, is in IdentityHashMap, which compares objects using
+System.identityHashCode(), which is not the same for different objects or their string literal equivalents.
+
+My recommendation, if you need to use IdentityHashMap with strings is to always use an explicit String.intern()
+for any keys -- unless you really want to keep every string as separate keys even if they are the same sequence,
+in which case, use new String(). This will work in Java and in JavaScript.
+
+Be aware when working with strings that come from SwingJS and are being used by other JavaScript modules
+that those that are String objects will return "object" for the JavaScript typeof operator, not "string".
+
+The easy way to ensure this is no problem is to concatenate strings with "" to force immediate interning:
+
+ var x = aJavaObject.getString() + "";
+
+unless you are certain that the string is being returned is a raw JavaScript string.
+
+Names with "$" and "_"
+----------------------
+
+For the most part, this should be no problem.
+
+Note that the use of $ and _ in Java field names has always been discouraged:
+[https://docs.oracle.com/javase/tutorial/java/nutsandbolts/variables.html]
+
+ You may find some situations where auto-generated names will contain the dollar sign,
+ but your variable names should always avoid using it. A similar convention
+ exists for the underscore character; while it's technically legal to begin your
+ variable's name with "_", this practice is discouraged.
+
+Some impacts of transpiling method names with full qualification:
+
+1) SwingJS will introduce fields that start with $ or _. These will not conflict
+ if the above convention is followed.
+
+2) Fields that have the same Java name as a method are not an issue.
+
+3) Fields that have a Java name with $ that matches a transpiled method name,
+ such as toString$, will need to be refactored in Java to not have that name collision.
+
+4) Fields in a subclass that have the same name as private fields in a superclass
+ represent a name collision, because the superclass method needs to call its private
+ field even if invoked from a subclass. The solution was to modify the subclass field
+ name using one or more prepended $.
+
+5) Use of Class.getDeclaredMethods() reflection will return Method objects having the transpiled
+ name, not the Java name. This could require some j2sNative adjustment
+ to strip the $... parameters from the name if that is needed.
+
+6) Use of Method.getParameterTypes() should work fine, provided class names
+ do not contain "_". This is because the transpiler converts "." to "_" when
+ creating the fully qualified JavaScript name.
+
+
+positive integers do not add to give negative numbers
+-----------------------------------------------------
+
+In Java, the following is true:
+
+ 2000000000 + 2000000000 == -294967296
+
+But in SwingJS, that will be 4000000000. So, for example, the following
+strategy will fail in SwingJS:
+
+ int newLength = lineBuf.length * 2;
+ if (newLength < 0) {
+ newLength = Integer.MAX_VALUE;
+ }
+
+"-1" in JavaScript is not 0xFFFFFFFF.
+
+And one must take care to not compare a negative number with a 32-bit mask. So
+
+(b & 0xFF000000) == 0xFF000000
+
+is true in Java for (int) b = -1, but is false in JavaScript, because 0xFF000000 is 4278190080,
+while (-1 & 0xFF000000) is, strangely enough, -16777216, and, in fact,
+
+(0xFF000000 & 0xFF000000) != 0xFF000000
+
+because -16777216 is not 4278190080.
+
+The fix is that one must compare similar operations:
+
+if ((b & 0xFF000000) == (0xFF000000 & 0xFF000000)) .....
+
+Importantly, the JavaScript Int32Array does behave properly. From
+the Firefox developer console:
+
+>> x = new Int32Array(1)
+<- Int32Array(1) [ 0 ]
+>> x[0] = 4000000000
+<- 4000000000
+>> x[0]
+<- -294967296
+
+Notice that, perhaps unexpectedly, the following two constructs produce
+different results in JavaScript:
+
+x = new Int32Array(1);
+b = x[0] = 4000000000;
+
+(b will be 4000000000)
+
+and
+
+x = new Int32Array(1);
+x[0] = 4000000000;
+b = x[0];
+
+(b will be -294967296)
+
+
+SwingJS leverages array typing to handle all byte and short arithmetic so as
+to ensure that any byte or short operation in JavaScript does give the same
+result in Java. The design decision to not also do this with integer math was
+a trade-off between performance and handling edge cases.
+
+
+ArrayIndexOutOfBounds
+---------------------
+
+You cannot implicitly throw an ArrayIndexOutOfBoundsException in JavaScript.
+JavaScript will simply return "undefined", not throw an Exception. So:
+
+boolean notAGoodIdeaIsOutOfBounds(String[] sa, int i) {
+ try {
+ return (sa[i] == sa[i]);
+ } catch (ArrayIndexOutOfBoundsException e) {
+ return false;
+ }
+}
+
+will work in Java but not in JavaScript. Code should not depend upon this sort
+of trap anyway, if you ask me.
+
+Throwable vs Error vs Exception
+-------------------------------
+
+True JavaScript errors are trapped as Throwable, whereas you can still trap
+Error and Exception as well. So if you want to be sure to catch any JavaScript
+error, use try{}catch (Throwable t){}, not try{}catch (Exception e){}.
+
+j
+ava.awt.Color
+--------------
+
+ColorSpace: only "support" CS_sRGB.
+
+ TODO -- any volunteers??
+
+
+javax.swing.JFileDialog
+-----------------------
+
+HTML5 cannot expose a file reading directory structure. But you certainly
+can still do file reading and writing. It just works a little differently.
+It's a simple modification:
+
+ b = new JButton("FileOpenDialog");
+ b.addActionListener(new ActionListener() {
+
+ @Override
+ public void actionPerformed(ActionEvent e) {
+ JFileChooser fc = new JFileChooser();
+ Test_Dialog.this.onDialogReturn(fc.showOpenDialog(Test_Dialog.this));
+ // Java will wait until the dialog is closed, then enter the onDialogReturn method.
+ // JavaScript will exit with NaN immediately, and then call back with its actual value
+ // asynchronously.
+ }
+
+ });
+
+ public void onDialogReturn(int value) {
+ if (value != Math.floor(value))
+ return; // in JavaScript, this will be NaN, indicating the dialog has been opened
+ // If we are here, the dialog has closed, in both Java and JavaScript.
+ System.out.println("int value is " + value);
+ }
+
+
+ @Override
+ public void propertyChange(PropertyChangeEvent event) {
+ Object val = event.getNewValue();
+ String name = event.getPropertyName();
+ System.out.println(name);
+ switch (event.getSource().getClass().getName()) {
+ case "javax.swing.JOptionPane":
+ switch (name) {
+ case "inputValue":
+ onDialogReturn(val);
+ return;
+ case "value":
+ if (val instanceof Integer)
+ onDialogReturn(((Integer) val).intValue());
+ else
+ onDialogReturn(val);
+ return;
+ }
+ break;
+ case "javax.swing.ColorChooserDialog":
+ switch (name) {
+ case "SelectedColor":
+ onDialogReturn(val);
+ return;
+ }
+ break;
+ case "javax.swing.JFileChooser":
+ switch (name) {
+ case "SelectedFile":
+ File file = (File) val;
+ byte[] array = (val == null ? null : /** @j2sNative file.秘bytes || */
+ null);
+ onDialogReturn("fileName is '" + file.getName() + "'\n\n" + new String(array));
+ return;
+ }
+ break;
+ }
+ System.out.println(
+ event.getSource().getClass().getName() + " " + event.getPropertyName() + ": " + event.getNewValue());
+ }
+
+
+Developers are encouraged to create a separate class that handles general calls to JFileDialog.
+An example class can be found in the SwingJS distribution as
+
+/sources/net.sf.j2s.java.core/src/javajs/async/AsyncFileChooser.java.
+
+
+javax.swing.JOptionPane dialogs
+-------------------------------
+
+For this action to work, the parentComponent must implement
+propertyChangeListener, and any call to JOptionPanel should allow for
+an asynchronous response, meaning that there is no actionable code following the
+call to the dialog opening.
+
+In addition, for compatibility with the Java version, implementation should
+wrap the call to getConfirmDialog or getOptionDialog in a method call to
+handle the Java:
+
+onDialogReturn(JOptionPane.showConfirmDialog(parentFrame,
+messageOrMessagePanel, "title", JOptionPane.OK_CANCEL_OPTION));
+
+Then parentFrame.propertyChange(event) should also call onDialogReturn.
+
+This will then work in both Java and JavaScript.
+
+Note that there is an int and an Object version of onDialogReturn().
+
+
+In JavaScript:
+
+The initial return from JOptionPane.showConfirmDialog and showMessageDialog
+will be (SwingJS) JDialog.ASYNCHRONOUS_INTEGER (NaN), testable as an impossible
+Java int value using ret != -(-ret) if the parent implements PropertyChangeListener, or -1
+(CLOSE_OPTION) if not.
+
+For showOptionDialog (which returns Object) or showInputDialog (which returns
+String), the initial return will be (SwingJS) JDialog.ASYNCHRONOUS_OBJECT, testable as
+((Object) ret) instanceof javax.swing.plaf.UIResource if the parent implements
+PropertyChangeListeneer, or null if not.
+
+The second return will be the desired return.
+
+In Java:
+
+The initial return will be the one and only modal final return.
+
+
+
+For full compatibility, The calling method must not continue beyond this
+call.
+
+All of the standard Java events associated with Components are also
+available.
+
+Certain fall back mechanisms are possible, where onReturn does not exist, but
+only for the following cases:
+
+
+For showMessageDialog, for WARNING_MESSAGE and ERROR_MESSAGE, a simple
+JavaScript alert() is used, returning 0 (OK_OPTION) or -1 (CLOSED_OPTION).
+
+For showInputDialog, if the message is a string, a simple JavaScript prompt()
+with input box is used, returning the entered string or null.
+
+For showConfirmDialog, a simple JavaScript confirm() is used, in which case:
+
+for YES_NO_OPTION: YES_OPTION or NO_OPTION
+
+for YES_NO_CANCEL_OPTION: YES_OPTION or CANCEL_OPTION
+
+for OK_CANCEL_OPTION or any other: OK_OPTION or CANCEL_OPTION
+
+Note that you should implement a response for CLOSED_OPTION for
+showConfirmDialog. For other dialogs, a null return indicates the dialog was
+closed, just as for Java.
+
+Developers are encouraged to create a separate class that handles general calls.
+An example class can be found in the SwingJS distribution as src/javajs/async/AsyncDialog.java.
+Very simple modifications to the Java allows asynchronous operation using AsyncDialog. Here
+is a simple "do you want to close this frame" example, where you can see that what we have
+done is to set the reply into an ActionListener that is defined in the constructor of
+the AsyncDisplay object:
+
+// Original:
+//
+// private void promptQuit() {
+// int sel = JOptionPane.showConfirmDialog(null, PROMPT_EXIT, NAME, JOptionPane.YES_NO_OPTION);
+// switch (sel) {
+// case JOptionPane.YES_OPTION:
+// resultsTab.clean();
+// seqs.dispose();
+// if (fromMain) {
+// System.exit(0);
+// }
+// break;
+// }
+// }
+
+ private void promptQuitAsync() {
+ new AsyncDialog(new ActionListener() {
+
+ @Override
+ public void actionPerformed(ActionEvent e) {
+ int sel = ((AsyncDialog)e.getSource()).getOption();
+ switch (sel) {
+ case JOptionPane.YES_OPTION:
+ resultsTab.clean();
+ seqs.dispose();
+ if (fromMain) {
+ System.exit(0);
+ }
+ break;
+ }
+ }}).showConfirmDialog(null, PROMPT_EXIT, NAME, JOptionPane.YES_NO_OPTION);
+ }
+
+Very simple!
+
+
+native methods
+--------------
+
+The J2S compiler ignores all static native method declarations.
+Anything of this nature needs to be implemented in JavaScript if it is needed,
+using j2sNative blocks:
+
+/**
+ * @j2sNative
+ *
+ * var putYourJavaScriptCodeHere
+ *
+ */
+
+ Note that if you follow that directly with a {...} block, then
+ the javadoc code will run in JavaScript, and the {...} code will run in Java.
+
+
+key Focus
+---------
+
+As of June, 2019, the keyboard focus manager is fully implemented.
+The one catch is that JTextPane and JTextArea, which already consume
+VK_TAB in Java, cannot use CTRL-TAB to continue a tabbing cycle around
+the components in a window. Instead, CTRL-TAB is absorbed by the browser.
+
+
+LookAndFeel and UI Classes
+--------------------------
+
+SwingJS implements the native browser look and feel as swingjs.plaf.HTML5LookAndFeel.
+There are small differences between all look and feels -- MacOS, Windows, SwingJS.
+
+Expert developers know how to coerce changes in the UI by subclassing the UI for a
+component. This probably will not work in SwingJS.
+
+Note that LookAndFeel in Java usually determines canvas size in a Frame because
+different operating systems (Mac OS vs Windows vs HTML5) will have
+different edge sizes on their frames. If you want to ensure a component size,
+use getContentPane().setPreferredSize().
+
+
+System.exit(0) does not stop all processes
+------------------------------------------
+
+Although System.ext(int) has been implemented in JavaScript, it just closes the
+frames, stops all pending javax.swing.Timer objects in the queue, and runs any
+threads added using Runtime.getRuntime().addShutdownHook(Thread).
+It may not stop all "threads." So don't rely on that.
+Applications are responsible for shutting down prior to executing System.exit(0).
+
+
+myClass.getField not implemented
+--------------------------------
+
+java.lang.reflect.Field is implemented minimally. It is not
+certain that Field.getDeclaringClass() will work. If you just want a
+value of a field, you can do this:
+
+/**
+ *@j2sNative
+ *
+ * return myClass[name]
+ */
+
+But that is not a java.lang.reflection.Field object.
+
+
+"window" and other reserved JavaScript names
+--------------------------------------------
+
+No reserved top-level JavaScript name is allowed for a package name. So, for example,
+one must rename packages such as "window" or "document" to names such as "win" or "doc".
+
+reserved field and method names
+-------------------------------
+
+In order to minimize the chance of added SwingJS field and method names colliding with ones
+developers might use in subclassing Java classes, we have added U+79D8 (first character of Mandarin
+"secret") to the characters already disrecommended by Java documentation ("$" and "_"). The only problem
+would be if you use that character followed by certain English words in certain classes. For example
+\u79D8canvas for JComponents (in java.awt.JSComponent) and \u79D8byte (in java.io.File).
+
+qualified field and method names
+--------------------------------
+
+Method names in SwingJS are fully qualified, meaning two methods with the same Java name but different
+parameters, such as write(int) and write(double), must not have the same name in JavaScript. (In this
+case, we will have write$I and write$D.) However, in certain cases it may be desirable to leave the
+method names unqualified. In particular, when an interface actually represents a JavaScript object,
+the transpiler can leave a method name unqualified. The default situation for this is a class name
+includes ".api.js" (case-sensitive). This means that any method in any class in a package js within
+a package api, or any private interface js that has an outer interface api, will have all-unqualified
+methods. An example of this is swingjs.plaf.JSComboPopupList, which needs to communicate with a jQuery
+object directly using the following interface:
+
+ private interface api {
+
+ interface js extends JQueryObject {
+
+ abstract js j2sCB(Object options);
+
+ abstract Object[] j2sCB(String method);
+
+ abstract Object[] j2sCB(String method, Object o);
+
+ abstract Object[] j2sCB(String method, int i);
+
+ abstract int j2sCB(String OPTION, String name);
+
+ }
+ }
+
+Notice that all these variants of j2sCB() will call the same method in JavaScript by design.
+
+
+missing Math methods
+--------------------
+
+java.lang.Math is worked out, but some methods are missing, either because they
+involve long integer value that are inaccessible in JavaScript, or because I just
+didn't implement them. This is a result of continued Java development.
+It is easy enough to add these methods if you have the source. They go into j2sClazz.js,
+which is combined with other initial libraries into swingjs2.js by build_site.xml
+
+
+Component.getGraphics(), Graphics.dispose()
+-------------------------------------------
+
+Use of component.getGraphics() is discouraged in Java and in SwingJS.
+Specifically in SwingJS, any call to component.getGraphics() or
+BufferedImage.createGraphics() or Graphics.create(...) should be matched with graphics.dispose(),
+particularly when it is called outside the context of a paint(Graphics)
+call from the system.
+
+If you see your graphics scrolling down the page with each repaint,
+look for where you have used Component.getGraphics() and not Graphics.dispose().
+For example, this will definitely NOT work in SwingJS:
+
+ this.paint(getGraphics())
+
+and really should not work in Java, either, as it is technically a resource memory leak.
+
+Instead, if you really do not want to use repaint(), use this:
+
+ Graphics g = getGraphics();
+ paint(g);
+ g.dispose();
+
+
+
+Graphics.setClip()
+------------------
+
+The HTML5 canvas.clip() method is permanent. You can only reset the clip using
+save/restore. This is different from Java, where you can temporarily change it using
+
+ Shape oldClip = Graphics.getClip();
+ Graphics.setClip(newClip);
+ ...
+ Graphics.setClip(oldClip);
+
+If you need to do something like this, you must schedule the paints
+to not have overlapping clip needs.
+
+
+MAJOR ISSUES--for Bob and Udo within SwingJS
+============================================
+
+fonts
+-----
+
+Fonts and FontMetrics will all be handled in JavaScript. Font matching will
+not be exact, and composite (drawn) fonts will not be supported.
+
+SwingJS handles calls such as font.getFontMetrics(g).stringWidth("xxx") by
+creating a <div> containing that text, placing it in an obscure location on
+the page, and reading div.getBoundingClientRect(). This is a VERY precise
+value, but can be a pixel or two off from what Java reports for the same font.
+
+
+OS-dependent classes
+--------------------
+
+Static classes such as:
+
+ java.awt.Toolkit
+ java.awt.GraphicsEnvironment
+
+
+which are created using Class.forName are implemented using classes in the swingjs package.
+
+AWTAccessor is not implemented.
+
+
+AWT component peers and component "ui" user interfaces
+------------------------------------------------------
+
+ComponentPeer is a class that represents a native AWT component.
+Components with such peers are called "heavy-weight" components.
+They are expected to do the dirty work of graphics drawing.
+
+Java Swing implements peers only for JApplet, JDialog, JFrame, and JWindow.
+References to such objects have been removed, but clearly there must be
+some connection to similar DOM objects, even for "light-weight" components.
+
+
+
+MAJOR ISSUES--to be resolved by implementers
+============================================
+
+fonts
+-----
+
+Glyph/composite/outline fonts are not supported.
+
+
+
+threads
+-------
+
+Thread locking and synchronization are not relevant to JavaScript.
+Thus, anything requiring "notify.." or "waitFor.." could be a serious issue.
+
+All threading must be "faked" in JavaScript. Specifically not available is:
+
+ Thread.sleep()
+
+javax.swing.AbstractButton#doClick(pressTime) will not work, as it requires Thread.sleep();
+
+However, java.lang.Thread itself is implemented and used extensively.
+
+Methods thread.start() and thread.run() both work fine.
+
+For simple applications that use Thread.sleep() just to have a delay, as in a frame rate, for
+example, one can use javax.swing.Timer instead. That is fully implemented.
+
+Likewise, java.util.Timer can be replaced with no loss of performance with javax.Swing.Timer.
+Note that java.util.TimerTask is implemented, but it can also be replaced by an implementation of Runnable.
+
+task = new TimerTask(){....};
+t = new java.util.Timer();
+t.schedule(task, 0, 1);
+
+becomes
+
+task = new TimerTask(){....}; // or task = new Runnable() {...}
+t = new javax.swing.Timer(1, new ActionListener() {
+ @Override
+ public void actionPerformed(ActionEvent e) {
+ task.run();
+ }
+};
+t.setInitialDelay(0); // not particularly necessary
+t.start();
+
+In addition, SwingJS provides swingjs.JSThread, which can be subclassed
+if desired. This class allows simple
+
+ while(!interrupted()){
+ wait()
+ ...
+ }
+
+action through an asynchronous function run1(mode). For example:
+
+ protected void run1(int mode) {
+ try {
+ while (true)
+ switch (mode) {
+ case INIT:
+ // once-through stuff here
+ mode = LOOP;
+ break;
+ case LOOP:
+ if (!doDispatch || isInterrupted()) {
+ mode = DONE;
+ } else {
+ Runnable r = new Runnable() {
+ public void run() {
+ // put the loop code here
+ }
+ };
+ dispatchAndReturn(r);
+ if (isJS)
+ return;
+ }
+ break;
+ // add more cases as needed
+ case DONE:
+ // finish up here
+ if (isInterrupted())
+ return;
+ // or here
+ break;
+ }
+ } finally {
+ // stuff here to be executed after each loop in JS or at the end in Java
+ }
+ }
+
+image loading
+-------------
+- All image loading in SwingJS is synchronous. A MediaTracker call will immediately return "complete".
+ However, it still may take one system clock tick to fully load images. Thus, it is recommended that
+ images be preloaded in the static block of the applet if it is necessary that they be available in init().
+ This is only an issue if you are trying to access the pixel buffer of the image in JavaScript.
+
+- Applet.getImage(path, name) will return null if the image does not exist.
+
+- BufferedImage: only "support" imageType RGB and ARGB
+
+ -BH: This is a temporary edit, just to get us started. Certainly GRAY will be needed
+
+
+BigInteger and BigDecimal
+-------------------------
+
+java.math.BigInteger is fully supported; java.math.BigDecimal is roughed
+in and not fully tested (07/2019).
+
+Both classes present significant issues for JavaScript, as they are based in
+Java's 64-bit long for all their operations. Here is the JavaDoc note I added
+to BigInteger:
+
+ * SwingJS note: Because of the limitations of JavaScript with regard
+ * to long-integer bit storage as a double, this implementation drops
+ * the integer storage bit length to 24, giving 48 for long and leaving
+ * the last 16 bits clear for the exponent of the double number. This should
+ * not affect performance significantly. It does increase the storage
+ * size by about 33%. By bringing an "int" to 3 bytes, we can easily construct
+ * and use byte[] data intended for the original BitSet.
+
+"Easily" may be a bit strong there. This was a serious challenge.
+
+BigDecimal seems to run normally, but in order to do that, my hack involves
+reducing the size of an integer that is allowed to be stored as such and not
+in byte[] as a BigInteger. I'm sure there is a performance hit, but it does work.
+
+no format internationalization
+------------------------------
+
+For now, just en for number and date formatters
+
+no winding rules
+----------------
+
+ When filling a graphic, only nonzero winding rule is implemented in HTML5 Canvas2D.
+
+
+
+text-related field implementation
+---------------------------------
+
+Text fields are:
+
+JTextField (JavaScript <input type="text">)
+JTextArea (JavaScript <textarea>)
+JTextPane (JavaScript <div>)
+JEditorPane (JavaScript <div>)
+
+For the initial implementation, we don't implement infinite undo/redo, and the abstract
+document model is much less elaborate. Only PlainDocument (in the form of JSPlainDocument)
+is implemented. The Document returned by JTextField.getDocument() is a javax.swing.text.Document.
+
+All scrolling is handled by HTML5. javax.swing.AutoScroller is not implemented.
+public static methods .stop, .isRunning, .processMouseDragged require true Java threading
+and so are not implmented. javax.swing.text.View and its subclasses are not implemented.
+
+The JS document model does not allow two text fields to address the same underlying document.
+
+JavaScript is slightly different from Java in that the field value is changed asynchronously after
+the keypressed event, so Java actions that are keyed to KEY_PRESSED may not pick up the new
+key value even after SwingUtilities.invokeLater() is called. Thus, key pressed actions may need
+to be recorded after a key released event instead.
+
+Formatter/Regex limitations
+---------------------------
+
+Some browsers cannot process Regex "look-behind" process such as (?<=\W)
+java.util.regex.Matcher and Pattern use JavaScript's RegExp object rather than
+the native Java object. These are not identical. Only flags /igm are supported.
+Matcher.start(groupID) is not supported.
+
+java.util.Formatter will function correctly for all standard %... patterns.
+
+integer 1/0 == Infinity
+-----------------------
+
+1/0 in Java throws "java.lang.ArithmeticException: / by zero", but in JavaScript is just Infinity.
+
+
+
+Summary
+-------
+
+These are all the known limitations of SwingJS. We have not found any of these limitations
+to be show-stoppers. The primary issue for newcomers to SwingJS is having the source code.
+You must check that source code for all your library jar files is available or, if you
+choose, you will need to decompile those classes. We have used decompilation on some projects,
+and it works just fine. So, technically, all we really need are JAR/class files. But the
+source is by far superior. It's generally prettier, and it has the license information that
+may or may not be present with the JAR or class files. Use class files at your own risk.
+
+Bob Hanson
+2019.08.16
+
+
+Additional Issues
+-----------------
+
+Annotation is working for classes, methods, and fields (12/22/19). Method reflection, however,
+is limited. Interfaces do not expose their methods, as the transpiler does not actually transpile
+the interfaces themselves. And method reflection only includes annotated methods.
+
+java.util.concurrent is not fully elaborated. This package is rewritten to not actually use the
+memory handling capabilities of concurrency, which JavaScript does not have access to.
+
+System.getProperties() just returns a minimal set of properties.
+
+
--- /dev/null
+20201219150605
git://source.jalview.org / jalview.git / commitdiff