X-Git-Url: http://source.jalview.org/gitweb/?a=blobdiff_plain;f=src%2Fjalview%2Fgui%2FSeqCanvas.java;h=123e649838d401e19ed9d4667303e7fa44712f79;hb=da8e34c5aeee5e83aa844d374eb21e4c2e3cebef;hp=795faffd3f0705eec5c09b2395c4bf2bf31e2804;hpb=3cdfc5e46776dbb8127f0a5b64df3545b988e3d9;p=jalview.git

diff --git a/src/jalview/gui/SeqCanvas.java b/src/jalview/gui/SeqCanvas.java
index 795faff..123e649 100755
--- a/src/jalview/gui/SeqCanvas.java
+++ b/src/jalview/gui/SeqCanvas.java
@@ -38,14 +38,14 @@ import java.awt.Color;
 import java.awt.FontMetrics;
 import java.awt.Graphics;
 import java.awt.Graphics2D;
+import java.awt.Rectangle;
 import java.awt.RenderingHints;
-import java.awt.Shape;
 import java.awt.image.BufferedImage;
 import java.beans.PropertyChangeEvent;
 import java.util.Iterator;
 import java.util.List;
 
-import javax.swing.JComponent;
+import javax.swing.JPanel;
 
 /**
  * The Swing component on which the alignment sequences, and annotations (if
@@ -53,7 +53,8 @@ import javax.swing.JComponent;
  * Wrapped mode, but not the scale above in Unwrapped mode.
  * 
  */
-public class SeqCanvas extends JComponent implements ViewportListenerI
+@SuppressWarnings("serial")
+public class SeqCanvas extends JPanel implements ViewportListenerI
 {
   /*
    * pixels gap between sequences and annotations when in wrapped mode
@@ -74,7 +75,7 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
 
   private final SequenceRenderer seqRdr;
 
-  private boolean fastPaint = false;
+  boolean fastPaint = false;
 
   private boolean fastpainting = false;
 
@@ -93,7 +94,8 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
 
   private int wrappedVisibleWidths; // number of wrapped widths displayed
 
-  private Graphics2D gg;
+  // Don't do this! Graphics handles are supposed to be transient
+  //private Graphics2D gg;
 
   /**
    * Creates a new SeqCanvas object.
@@ -114,7 +116,7 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
 
   public SequenceRenderer getSequenceRenderer()
   {
-    return seqRdr;
+    return seqRdr; 
   }
 
   public FeatureRenderer getFeatureRenderer()
@@ -200,7 +202,7 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
     int yPos = ypos + charHeight;
     int startX = startx;
     int endX = endx;
-
+    
     if (av.hasHiddenColumns())
     {
       HiddenColumns hiddenColumns = av.getAlignment().getHiddenColumns();
@@ -236,6 +238,7 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
         }
       }
 
+      
       /*
        * white fill the space for the scale
        */
@@ -260,6 +263,7 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
         g.drawString(valueAsString, xOffset, y);
       }
     }
+
   }
 
   /**
@@ -273,6 +277,7 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
    * <li>scrolling by trackpad, middle mouse button, or other device</li>
    * <li>by moving the box in the Overview window</li>
    * <li>programmatically to make a highlighted position visible</li>
+   * <li>pasting a block of sequences</li>
    * </ul>
    * 
    * @param horizontal
@@ -282,18 +287,21 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
    */
   public void fastPaint(int horizontal, int vertical)
   {
-    if (fastpainting || gg == null || img == null)
+
+    // effectively:
+    // if (horizontal != 0 && vertical != 0)
+    // throw new InvalidArgumentException();
+    if (fastpainting || img == null)
     {
       return;
     }
     fastpainting = true;
     fastPaint = true;
-
     try
     {
       int charHeight = av.getCharHeight();
       int charWidth = av.getCharWidth();
-    
+
       ViewportRanges ranges = av.getRanges();
       int startRes = ranges.getStartRes();
       int endRes = ranges.getEndRes();
@@ -301,10 +309,6 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
       int endSeq = ranges.getEndSeq();
       int transX = 0;
       int transY = 0;
-      
-      gg.copyArea(horizontal * charWidth, vertical * charHeight,
-              img.getWidth(), img.getHeight(), -horizontal * charWidth,
-              -vertical * charHeight);
 
       if (horizontal > 0) // scrollbar pulled right, image to the left
       {
@@ -339,13 +343,24 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
         }
       }
 
+
+      // System.err.println(">>> FastPaint to " + transX + " " + transY + " "
+      // + horizontal + " " + vertical + " " + startRes + " " + endRes
+      // + " " + startSeq + " " + endSeq);
+
+      Graphics gg = img.getGraphics();
+      gg.copyArea(horizontal * charWidth, vertical * charHeight,
+              img.getWidth(), img.getHeight(), -horizontal * charWidth,
+              -vertical * charHeight);
       gg.translate(transX, transY);
       drawPanel(gg, startRes, endRes, startSeq, endSeq, 0);
       gg.translate(-transX, -transY);
+      gg.dispose();
 
       // Call repaint on alignment panel so that repaints from other alignment
       // panel components can be aggregated. Otherwise performance of the
       // overview window and others may be adversely affected.
+      // System.out.println("SeqCanvas fastPaint() repaint() request...");
       av.getAlignPanel().repaint();
     } finally
     {
@@ -356,73 +371,109 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
   @Override
   public void paintComponent(Graphics g)
   {
-    super.paintComponent(g);    
-    
+
+    if (av.getAlignPanel().getHoldRepaint())
+    {
+      return;
+    }
     int charHeight = av.getCharHeight();
     int charWidth = av.getCharWidth();
-    
+
+    int availWidth = getWidth();
+    int availHeight = getHeight();
+
+    availWidth -= (availWidth % charWidth);
+    availHeight -= (availHeight % charHeight);
+
+    // BH 2019 can't possibly fastPaint if either width or height is 0
+
+    if (availWidth == 0 || availHeight == 0)
+    {
+      return;
+    }
+
     ViewportRanges ranges = av.getRanges();
-    
-    int width = getWidth();
-    int height = getHeight();
-    
-    width -= (width % charWidth);
-    height -= (height % charHeight);
-    
-    if ((img != null) && (fastPaint
-            || (getVisibleRect().width != g.getClipBounds().width)
-            || (getVisibleRect().height != g.getClipBounds().height)))
+    int startRes = ranges.getStartRes();
+    int startSeq = ranges.getStartSeq();
+    int endRes = ranges.getEndRes();
+    int endSeq = ranges.getEndSeq();
+
+    // [JAL-3226] problem that JavaScript (or Java) may consolidate multiple
+    // repaint() requests in unpredictable ways. In this case, the issue was
+    // that in response to a CTRL-C/CTRL-V paste request, in Java a fast
+    // repaint request preceded two full requests, thus resulting
+    // in a full request for paint. In constrast, in JavaScript, the three
+    // requests were bundled together into one, so the fastPaint flag was
+    // still present for the second and third request.
+    //
+    // This resulted in incomplete painting.
+    //
+    // The solution was to set seqCanvas.fastPaint and idCanvas.fastPaint false
+    // in PaintRefresher when the target to be painted is one of those two
+    // components.
+    //
+    // BH 2019.04.22
+    //
+    // An initial idea; can be removed once we determine this issue is closed:
+    // if (av.isFastPaintDisabled())
+    // {
+    // fastPaint = false;
+    // }
+
+    Rectangle vis, clip;
+    if (img != null
+            && (fastPaint
+                    || (vis = getVisibleRect()).width != (clip = g
+                            .getClipBounds()).width
+                    || vis.height != clip.height))
     {
       g.drawImage(img, 0, 0, this);
-
-      drawSelectionGroup((Graphics2D) g, ranges.getStartRes(),
-              ranges.getEndRes(), ranges.getStartSeq(), ranges.getEndSeq());
-
+      drawSelectionGroup((Graphics2D) g, startRes, endRes, startSeq,
+              endSeq);
       fastPaint = false;
     }
-    else if (width > 0 && height > 0)
+    else
     {
-      /*
-       * img is a cached version of the last view we drew, if any
-       * if we have no img or the size has changed, make a new one
-       */
-      if (img == null || width != img.getWidth()
-              || height != img.getHeight())
+      // img is a cached version of the last view we drew.
+      // If we have no img or the size has changed, make a new one.
+      //
+      if (img == null || availWidth != img.getWidth()
+              || availHeight != img.getHeight())
       {
-        img = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
-        gg = (Graphics2D) img.getGraphics();
-        gg.setFont(av.getFont());
+        img = new BufferedImage(availWidth, availHeight,
+                BufferedImage.TYPE_INT_RGB);
       }
-    
+
+      Graphics2D gg = (Graphics2D) img.getGraphics();
+      gg.setFont(av.getFont());
+
       if (av.antiAlias)
       {
         gg.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                 RenderingHints.VALUE_ANTIALIAS_ON);
       }
-    
+
       gg.setColor(Color.white);
-      gg.fillRect(0, 0, img.getWidth(), img.getHeight());
-    
+      gg.fillRect(0, 0, availWidth, availHeight);
+
       if (av.getWrapAlignment())
       {
-        drawWrappedPanel(gg, getWidth(), getHeight(), ranges.getStartRes());
+        drawWrappedPanel(gg, availWidth, availHeight, ranges.getStartRes());
       }
       else
       {
-        drawPanel(gg, ranges.getStartRes(), ranges.getEndRes(),
-                ranges.getStartSeq(), ranges.getEndSeq(), 0);
+        drawPanel(gg, startRes, endRes, startSeq, endSeq, 0);
       }
 
-      drawSelectionGroup(gg, ranges.getStartRes(),
-              ranges.getEndRes(), ranges.getStartSeq(), ranges.getEndSeq());
+      drawSelectionGroup(gg, startRes, endRes, startSeq, endSeq);
 
       g.drawImage(img, 0, 0, this);
+      gg.dispose();
     }
 
     if (av.cursorMode)
     {
-      drawCursor(g, ranges.getStartRes(), ranges.getEndRes(),
-              ranges.getStartSeq(), ranges.getEndSeq());
+      drawCursor(g, startRes, endRes, startSeq, endSeq);
     }
   }
   
@@ -475,35 +526,31 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
   }
 
   /**
-   * Returns the visible width of the canvas in residues, after allowing for
-   * East or West scales (if shown)
+   * Using the current font, determine fields labelWidthEast and labelWidthWest,
+   * and return the number of residues that can fill the remaining width.
    * 
-   * @param canvasWidth
+   * @param width
    *          the width in pixels (possibly including scales)
    * 
-   * @return
+   * @return the visible width in residues, after allowing for East or West
+   *         scales (if shown)
+   * 
    */
-  public int getWrappedCanvasWidth(int canvasWidth)
+  public int getWrappedCanvasWidth(int width)
   {
     int charWidth = av.getCharWidth();
 
     FontMetrics fm = getFontMetrics(av.getFont());
 
-    int labelWidth = 0;
-    
-    if (av.getScaleRightWrapped() || av.getScaleLeftWrapped())
-    {
-      labelWidth = getLabelWidth(fm);
-    }
+    int labelWidth = (av.getScaleRightWrapped() || av.getScaleLeftWrapped()
+            ? getLabelWidth(fm)
+            : 0);
 
     labelWidthEast = av.getScaleRightWrapped() ? labelWidth : 0;
 
     labelWidthWest = av.getScaleLeftWrapped() ? labelWidth : 0;
 
-    System.out.println(Thread.currentThread().getName()
-            + " " + System.currentTimeMillis() + " labelWidthWest: "
-            + labelWidthWest);
-    return (canvasWidth - labelWidthEast - labelWidthWest) / charWidth;
+    return (width - labelWidthEast - labelWidthWest) / charWidth;
   }
 
   /**
@@ -529,6 +576,7 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
       maxWidth = Math.max(maxWidth, alignment.getSequenceAt(i).getEnd());
     }
 
+    // quick int log10
     int length = 0;
     for (int i = maxWidth; i > 0; i /= 10)
     {
@@ -543,18 +591,18 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
    * window
    * 
    * @param g
-   * @param canvasWidth
+   * @param availWidth
    *          available width in pixels
-   * @param canvasHeight
+   * @param availHeight
    *          available height in pixels
    * @param startColumn
    *          the first column (0...) of the alignment to draw
    */
-  public void drawWrappedPanel(Graphics g, int canvasWidth,
-          int canvasHeight, final int startColumn)
+  public void drawWrappedPanel(Graphics g, int availWidth, int availHeight,
+          final int startColumn)
   {
-    int wrappedWidthInResidues = calculateWrappedGeometry(canvasWidth,
-            canvasHeight);
+    int wrappedWidthInResidues = calculateWrappedGeometry(availWidth,
+            availHeight);
 
     av.setWrappedWidth(wrappedWidthInResidues);
 
@@ -564,7 +612,7 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
     // we need to call this again to make sure the startColumn +
     // wrappedWidthInResidues values are used to calculate wrappedVisibleWidths
     // correctly.
-    calculateWrappedGeometry(canvasWidth, canvasHeight);
+    calculateWrappedGeometry(availWidth, availHeight);
 
     /*
      * draw one width at a time (excluding any scales shown),
@@ -579,7 +627,7 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
     {
       int endColumn = Math
               .min(maxWidth, start + wrappedWidthInResidues - 1);
-      drawWrappedWidth(g, ypos, start, endColumn, canvasHeight);
+      drawWrappedWidth(g, ypos, start, endColumn, availHeight);
       ypos += wrappedRepeatHeightPx;
       start += wrappedWidthInResidues;
       currentWidth++;
@@ -598,11 +646,11 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
    * <li>whether scales are shown left, right or above the alignment</li>
    * </ul>
    * 
-   * @param canvasWidth
-   * @param canvasHeight
+   * @param availWidth
+   * @param availHeight
    * @return the number of residue columns in each width
    */
-  protected int calculateWrappedGeometry(int canvasWidth, int canvasHeight)
+  protected int calculateWrappedGeometry(int availWidth, int availHeight)
   {
     int charHeight = av.getCharHeight();
 
@@ -636,8 +684,8 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
      * ensuring a part height includes at least one sequence
      */
     ViewportRanges ranges = av.getRanges();
-    wrappedVisibleWidths = canvasHeight / wrappedRepeatHeightPx;
-    int remainder = canvasHeight % wrappedRepeatHeightPx;
+    wrappedVisibleWidths = availHeight / wrappedRepeatHeightPx;
+    int remainder = availHeight % wrappedRepeatHeightPx;
     if (remainder >= (wrappedSpaceAboveAlignment + charHeight))
     {
       wrappedVisibleWidths++;
@@ -646,7 +694,7 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
     /*
      * compute width in residues; this also sets East and West label widths
      */
-    int wrappedWidthInResidues = getWrappedCanvasWidth(canvasWidth);
+    int wrappedWidthInResidues = getWrappedCanvasWidth(availWidth);
 
     /*
      *  limit visibleWidths to not exceed width of alignment
@@ -691,21 +739,8 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
     int xOffset = labelWidthWest
             + ((startColumn - ranges.getStartRes()) % viewportWidth)
             * charWidth;
-    g.translate(xOffset, 0);
-
-    // When printing we have an extra clipped region,
-    // the Printable page which we need to account for here
-    Shape clip = g.getClip();
 
-    if (clip == null)
-    {
-      g.setClip(0, 0, viewportWidth * charWidth, canvasHeight);
-    }
-    else
-    {
-      g.setClip(0, (int) clip.getBounds().getY(),
-              viewportWidth * charWidth, (int) clip.getBounds().getHeight());
-    }
+    g.translate(xOffset, 0);
 
     /*
      * white fill the region to be drawn (so incremental fast paint doesn't
@@ -733,7 +768,6 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
               startColumn, endx + 1);
       g.translate(0, -yShift);
     }
-    g.setClip(clip);
     g.translate(-xOffset, 0);
   }
 
@@ -749,6 +783,7 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
     int charWidth = av.getCharWidth();
 
     g.setFont(av.getFont());
+
     g.setColor(Color.black);
 
     int ypos = wrappedSpaceAboveAlignment;
@@ -770,6 +805,7 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
       if (av.getScaleRightWrapped())
       {
         int x = labelWidthWest + viewportWidth * charWidth;
+        
         g.translate(x, 0);
         drawVerticalScale(g, startCol, endColumn, ypos, false);
         g.translate(-x, 0);
@@ -1102,23 +1138,17 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
       do
       {
         g.setColor(group.getOutlineColour());
-
         drawPartialGroupOutline(g, group, startRes, endRes, startSeq,
                 endSeq, offset);
 
         groupIndex++;
-
         if (groupIndex >= av.getAlignment().getGroups().size())
         {
           break;
         }
-
         group = av.getAlignment().getGroups().get(groupIndex);
-
       } while (groupIndex < av.getAlignment().getGroups().size());
-
     }
-
   }
 
   /**
@@ -1464,20 +1494,42 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
    * Highlights search results in the visible region by rendering as white text
    * on a black background. Any previous highlighting is removed. Answers true
    * if any highlight was left on the visible alignment (so status bar should be
+   * set to match), else false. This method does _not_ set the 'fastPaint' flag,
+   * so allows the next repaint to update the whole display.
+   * 
+   * @param results
+   * @return
+   */
+  public boolean highlightSearchResults(SearchResultsI results)
+  {
+    return highlightSearchResults(results, false);
+
+  }
+  
+  /**
+   * Highlights search results in the visible region by rendering as white text
+   * on a black background. Any previous highlighting is removed. Answers true
+   * if any highlight was left on the visible alignment (so status bar should be
    * set to match), else false.
    * <p>
-   * Currently fastPaint is not implemented for wrapped alignments. If a wrapped
-   * alignment had to be scrolled to show the highlighted region, then it should
-   * be fully redrawn, otherwise a fast paint can be performed. This argument
-   * could be removed if fast paint of scrolled wrapped alignment is coded in
-   * future (JAL-2609).
+   * Optionally, set the 'fastPaint' flag for a faster redraw if only the
+   * highlighted regions are modified. This speeds up highlighting across linked
+   * alignments.
+   * <p>
+   * Currently fastPaint is not implemented for scrolled wrapped alignments. If
+   * a wrapped alignment had to be scrolled to show the highlighted region, then
+   * it should be fully redrawn, otherwise a fast paint can be performed. This
+   * argument could be removed if fast paint of scrolled wrapped alignment is
+   * coded in future (JAL-2609).
    * 
    * @param results
-   * @param noFastPaint
+   * @param doFastPaint
+   *          if true, sets a flag so the next repaint only redraws the modified
+   *          image
    * @return
    */
   public boolean highlightSearchResults(SearchResultsI results,
-          boolean noFastPaint)
+          boolean doFastPaint)
   {
     if (fastpainting)
     {
@@ -1486,7 +1538,7 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
     boolean wrapped = av.getWrapAlignment();
     try
     {
-      fastPaint = !noFastPaint;
+      fastPaint = doFastPaint;
       fastpainting = fastPaint;
 
       /*
@@ -1543,7 +1595,7 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
    */
   protected boolean drawMappedPositions(SearchResultsI results)
   {
-    if ((results == null) || (gg == null)) // JAL-2784 check gg is not null
+    if ((results == null) || (img == null)) // JAL-2784 check gg is not null
     {
       return false;
     }
@@ -1615,9 +1667,11 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
       }
       int transX = (firstCol - ranges.getStartRes()) * av.getCharWidth();
       int transY = (firstSeq - ranges.getStartSeq()) * av.getCharHeight();
+      Graphics gg = img.getGraphics();
       gg.translate(transX, transY);
       drawPanel(gg, firstCol, lastCol, firstSeq, lastSeq, 0);
       gg.translate(-transX, -transY);
+      gg.dispose();
     }
 
     return matchFound;
@@ -1628,90 +1682,163 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
   {
     String eventName = evt.getPropertyName();
 
-    if (eventName.equals(SequenceGroup.SEQ_GROUP_CHANGED))
+    // BH 2019.07.27 removes dead code introduced in aad3650 and simplifies
+    // logic, emphasizing no check for ENDRES or ENDSEQ
+
+    // Both scrolling and resizing change viewport ranges: scrolling changes
+    // both start and end points, but resize only changes end values.
+    // Here we only want to fastpaint on a scroll, with resize using a normal
+    // paint, so scroll events are identified as changes to the horizontal or
+    // vertical start value.
+
+    // Make sure we're not trying to draw a panel
+    // larger than the visible window
+    int scrollX = 0;
+    int scrollY = 0;
+    switch (eventName)
     {
+    case SequenceGroup.SEQ_GROUP_CHANGED:
       fastPaint = true;
       repaint();
       return;
-    }
-    else if (eventName.equals(ViewportRanges.MOVE_VIEWPORT))
-    {
+    case ViewportRanges.MOVE_VIEWPORT:
       fastPaint = false;
       repaint();
       return;
-    }
-
-    int scrollX = 0;
-    if (eventName.equals(ViewportRanges.STARTRES)
-            || eventName.equals(ViewportRanges.STARTRESANDSEQ))
-    {
-      // Make sure we're not trying to draw a panel
-      // larger than the visible window
-      if (eventName.equals(ViewportRanges.STARTRES))
-      {
-        scrollX = (int) evt.getNewValue() - (int) evt.getOldValue();
-      }
-      else
+    case ViewportRanges.STARTSEQ:
+      // meaning STARTOREND
+      // typically scroll, but possibly just the end changed
+      fastPaint(0, (int) evt.getNewValue() - (int) evt.getOldValue());
+      return;
+    case ViewportRanges.ENDRES:
+    case ViewportRanges.ENDSEQ:
+      // meaning second event along with "START" -- ENDONLY,NOTSTART
+      // TODO: ignore??
+      return;
+    case ViewportRanges.STARTRES:
+      // meaning STARTOREND
+      scrollX = (int) evt.getNewValue() - (int) evt.getOldValue();
+      break;
+    case ViewportRanges.STARTRESANDSEQ:
+      scrollX = ((int[]) evt.getNewValue())[0]
+              - ((int[]) evt.getOldValue())[0];
+      scrollY = ((int[]) evt.getNewValue())[1]
+              - ((int[]) evt.getOldValue())[1];
+
+      // System.out.println("SC dx dy " + scrollX + " " + scrollY);
+
+      if (scrollX != 0 && scrollY != 0)
       {
-        scrollX = ((int[]) evt.getNewValue())[0]
-                - ((int[]) evt.getOldValue())[0];
-      }
-      ViewportRanges vpRanges = av.getRanges();
+        // all sorts of problems in JavaScript if this is commented out.
+        repaint();
+        return;
 
-      int range = vpRanges.getEndRes() - vpRanges.getStartRes() + 1;
-      if (scrollX > range)
-      {
-        scrollX = range;
-      }
-      else if (scrollX < -range)
-      {
-        scrollX = -range;
       }
+      break;
     }
-      // Both scrolling and resizing change viewport ranges: scrolling changes
-      // both start and end points, but resize only changes end values.
-      // Here we only want to fastpaint on a scroll, with resize using a normal
-      // paint, so scroll events are identified as changes to the horizontal or
-      // vertical start value.
-      if (eventName.equals(ViewportRanges.STARTRES))
-      {
-    	  if (av.getWrapAlignment())
-          {
-            fastPaintWrapped(scrollX);
-          }
-          else
-          {
-            fastPaint(scrollX, 0);
-          }
-      }
-      else if (eventName.equals(ViewportRanges.STARTSEQ))
-      {
-        // scroll
-        fastPaint(0, (int) evt.getNewValue() - (int) evt.getOldValue());
-      }
-      else if (eventName.equals(ViewportRanges.STARTRESANDSEQ))
-      {
-        if (av.getWrapAlignment())
-        {
-          fastPaintWrapped(scrollX);
-        }
-        else
-        {
-          fastPaint(scrollX, 0);
-        }
-    }
-    else if (eventName.equals(ViewportRanges.STARTSEQ))
+
+    ViewportRanges vpRanges = av.getRanges();
+    int range = vpRanges.getEndRes() - vpRanges.getStartRes() + 1;
+    scrollX = Math.max(Math.min(scrollX, range), -range);
+    // only STARTRES or STARTRESANDSEQ:
+    if (av.getWrapAlignment())
     {
-      // scroll
-      fastPaint(0, (int) evt.getNewValue() - (int) evt.getOldValue());
+      fastPaintWrapped(scrollX);
     }
-    else if (eventName.equals(ViewportRanges.STARTRESANDSEQ))
+    else
     {
-      if (av.getWrapAlignment())
-      {
-        fastPaintWrapped(scrollX);
-      }
-    }
+      fastPaint(scrollX, scrollY);
+    }
+
+    // BH 2019.07.27 was:
+    // if (eventName.equals(SequenceGroup.SEQ_GROUP_CHANGED))
+    // {
+    // fastPaint = true;
+    // repaint();
+    // return;
+    // }
+    // else if (eventName.equals(ViewportRanges.MOVE_VIEWPORT))
+    // {
+    // fastPaint = false;
+    // // System.err.println("!!!! fastPaint false from MOVE_VIEWPORT");
+    // repaint();
+    // return;
+    // }
+    //
+    // if (eventName.equals(ViewportRanges.STARTRES)
+    // || eventName.equals(ViewportRanges.STARTRESANDSEQ))
+    // {
+    // // Make sure we're not trying to draw a panel
+    // // larger than the visible window
+    // if (eventName.equals(ViewportRanges.STARTRES))
+    // {
+    // scrollX = (int) evt.getNewValue() - (int) evt.getOldValue();
+    // }
+    // else
+    // {
+    // scrollX = ((int[]) evt.getNewValue())[0]
+    // - ((int[]) evt.getOldValue())[0];
+    // }
+    // ViewportRanges vpRanges = av.getRanges();
+    //
+    // int range = vpRanges.getEndRes() - vpRanges.getStartRes() + 1;
+    // if (scrollX > range)
+    // {
+    // scrollX = range;
+    // }
+    // else if (scrollX < -range)
+    // {
+    // scrollX = -range;
+    // }
+    // }
+    // Both scrolling and resizing change viewport ranges: scrolling changes
+    // both start and end points, but resize only changes end values.
+    // Here we only want to fastpaint on a scroll, with resize using a normal
+    // paint, so scroll events are identified as changes to the horizontal or
+    // vertical start value.
+    // BH 2019.07.27 was:
+    // if (eventName.equals(ViewportRanges.STARTRES))
+    // {
+    // if (av.getWrapAlignment())
+    // {
+    // fastPaintWrapped(scrollX);
+    // }
+    // else
+    // {
+    // fastPaint(scrollX, 0);
+    // }
+    // }
+    // else if (eventName.equals(ViewportRanges.STARTSEQ))
+    // {
+    // // scroll
+    // fastPaint(0, (int) evt.getNewValue() - (int) evt.getOldValue());
+    // }
+    // else if (eventName.equals(ViewportRanges.STARTRESANDSEQ))
+    // {
+    // if (av.getWrapAlignment())
+    // {
+    // fastPaintWrapped(scrollX);
+    // }
+    // else
+    // {
+    // fastPaint(scrollX, 0);
+    // }
+    // }
+    //
+    // BH oops!
+    //
+    // else if (eventName.equals(ViewportRanges.STARTSEQ))
+    // {
+    // // scroll
+    // fastPaint(0, (int) evt.getNewValue() - (int) evt.getOldValue());
+    // }
+    // else if (eventName.equals(ViewportRanges.STARTRESANDSEQ))
+    // {
+    // if (av.getWrapAlignment())
+    // {
+    // fastPaintWrapped(scrollX);
+    // }
+    // }
   }
 
   /**
@@ -1738,7 +1865,7 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
       return;
     }
 
-    if (fastpainting || gg == null)
+    if (fastpainting || img == null)
     {
       return;
     }
@@ -1748,6 +1875,9 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
 
     try
     {
+      
+      Graphics gg = img.getGraphics();
+      
       calculateWrappedGeometry(getWidth(), getHeight());
 
       /*
@@ -1776,6 +1906,8 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
        */
       drawWrappedDecorators(gg, ranges.getStartRes());
 
+      gg.dispose();
+      
       repaint();
     } finally
     {
@@ -1799,6 +1931,8 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
       return;
     }
 
+    Graphics gg = img.getGraphics();
+    
     ViewportRanges ranges = av.getRanges();
     int viewportWidth = ranges.getViewportWidth();
     int charWidth = av.getCharWidth();
@@ -1825,6 +1959,8 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
       /*
        * white fill first to erase annotations
        */
+      
+      
       gg.translate(xOffset, 0);
       gg.setColor(Color.white);
       gg.fillRect(labelWidthWest, ypos,
@@ -1832,6 +1968,7 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
       gg.translate(-xOffset, 0);
 
       drawWrappedWidth(gg, ypos, startRes, endRes, canvasHeight);
+      
     }
 
     /*
@@ -1875,7 +2012,8 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
       gg.setColor(Color.white);
       gg.fillRect(0, canvasHeight - heightBelow, getWidth(), heightBelow);
     }
-  }
+    gg.dispose();
+ }
 
   /**
    * Shifts the visible alignment by the specified number of columns - left if
@@ -1891,6 +2029,9 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
     {
       return;
     }
+
+    Graphics gg = img.getGraphics();
+
     int charWidth = av.getCharWidth();
 
     int canvasHeight = getHeight();
@@ -1964,11 +2105,11 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
                   * charWidth, heightToCopy, widthToCopy,
                   -wrappedRepeatHeightPx);
         }
-
         y += wrappedRepeatHeightPx;
         xpos += viewportWidth;
       }
     }
+    gg.dispose();
   }
 
   
@@ -1984,7 +2125,7 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
    */
   protected boolean drawMappedPositionsWrapped(SearchResultsI results)
   {
-    if ((results == null) || (gg == null)) // JAL-2784 check gg is not null
+    if ((results == null) || (img == null)) // JAL-2784 check gg is not null
     {
       return false;
     }
@@ -2019,6 +2160,9 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
 
     int gapHeight = charHeight * (av.getScaleAboveWrapped() ? 2 : 1);
 
+    
+    Graphics gg = img.getGraphics();
+
     for (int seqNo = ranges.getStartSeq(); seqNo <= ranges
             .getEndSeq(); seqNo++)
     {
@@ -2089,6 +2233,8 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
       }
     }
   
+    gg.dispose();
+
     return matchFound;
   }
 
@@ -2101,4 +2247,5 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
   {
     return labelWidthWest;
   }
+
 }