JAL-2600 Add in IdCanvas and checks for 0 size images

[jalview.git] / src / jalview / gui / IdCanvas.java

diff --git a/src/jalview/gui/IdCanvas.java b/src/jalview/gui/IdCanvas.java
index 5ce36cb..cfbc403 100755 (executable)
--- a/src/jalview/gui/IdCanvas.java
+++ b/src/jalview/gui/IdCanvas.java
@@ -153,7 +153,7 @@ public class IdCanvas extends JPanel implements ViewportListenerI
    * @param vertical
    *          DOCUMENT ME!
    */
-  public void fastPaint(int vertical)
+  public void fastPaint(int vertical, boolean isresize)
   {
     if (gg == null)
     {
@@ -171,26 +171,37 @@ public class IdCanvas extends JPanel implements ViewportListenerI
     int es = ranges.getEndSeq();
     int transY = 0;
 
-    if (vertical > 0) // scroll down
+    if (isresize)
     {
-      ss = es - vertical;
-
-      if (ss < ranges.getStartSeq())
-      { // ie scrolling too fast, more than a page at a time
-        ss = ranges.getStartSeq();
-      }
-      else
+      if (vertical != 0)
       {
         transY = imgHeight - ((vertical + 1) * av.getCharHeight());
+        ss = es - vertical - ss;
       }
     }
-    else if (vertical < 0) // scroll up
+    else
     {
-      es = ss - vertical;
+      if (vertical > 0) // scroll down
+      {
+        ss = es - vertical;
 
-      if (es > ranges.getEndSeq())
+        if (ss < ranges.getStartSeq())
+        { // ie scrolling too fast, more than a page at a time
+          ss = ranges.getStartSeq();
+        }
+        else
+        {
+          transY = imgHeight - ((vertical + 1) * av.getCharHeight());
+        }
+      }
+      else if (vertical < 0) // scroll up
       {
-        es = ranges.getEndSeq();
+        es = ss - vertical;
+
+        if (es > ranges.getEndSeq())
+        {
+          es = ranges.getEndSeq();
+        }
       }
     }
 
@@ -524,10 +535,13 @@ public class IdCanvas extends JPanel implements ViewportListenerI
   public void propertyChange(PropertyChangeEvent evt)
   {
     // Respond to viewport range changes (e.g. alignment panel was scrolled)
-    if (evt.getPropertyName().equals("startseq")
-            || evt.getPropertyName().equals("endseq"))
+    if (evt.getPropertyName().equals("startseq"))
+    {
+      fastPaint((int) evt.getNewValue() - (int) evt.getOldValue(), false);
+    }
+    else if (evt.getPropertyName().equals("endseq"))
     {
-      fastPaint((int) evt.getNewValue() - (int) evt.getOldValue());
+      fastPaint((int) evt.getNewValue() - (int) evt.getOldValue(), true);
     }
   }
 }