JAL-2609 erase space below, and other fixes

diff --git a/src/jalview/gui/SeqCanvas.java b/src/jalview/gui/SeqCanvas.java
index 785b71d..12b426d 100755 (executable)
--- a/src/jalview/gui/SeqCanvas.java
+++ b/src/jalview/gui/SeqCanvas.java
@@ -270,57 +270,63 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
     }
     fastpainting = true;
     fastPaint = true;
-    updateViewport();
 
-    ViewportRanges ranges = av.getRanges();
-    int startRes = ranges.getStartRes();
-    int endRes = ranges.getEndRes();
-    int startSeq = ranges.getStartSeq();
-    int endSeq = ranges.getEndSeq();
-    int transX = 0;
-    int transY = 0;
+    try
+    {
+      updateViewport();
 
-    gg.copyArea(horizontal * charWidth, vertical * charHeight, imgWidth,
-            imgHeight, -horizontal * charWidth, -vertical * charHeight);
+      ViewportRanges ranges = av.getRanges();
+      int startRes = ranges.getStartRes();
+      int endRes = ranges.getEndRes();
+      int startSeq = ranges.getStartSeq();
+      int endSeq = ranges.getEndSeq();
+      int transX = 0;
+      int transY = 0;
 
-    if (horizontal > 0) // scrollbar pulled right, image to the left
-    {
-      transX = (endRes - startRes - horizontal) * charWidth;
-      startRes = endRes - horizontal;
-    }
-    else if (horizontal < 0)
-    {
-      endRes = startRes - horizontal;
-    }
-    else if (vertical > 0) // scroll down
-    {
-      startSeq = endSeq - vertical;
+      gg.copyArea(horizontal * charWidth, vertical * charHeight, imgWidth,
+              imgHeight, -horizontal * charWidth, -vertical * charHeight);
 
-      if (startSeq < ranges.getStartSeq())
-      { // ie scrolling too fast, more than a page at a time
-        startSeq = ranges.getStartSeq();
+      if (horizontal > 0) // scrollbar pulled right, image to the left
+      {
+        transX = (endRes - startRes - horizontal) * charWidth;
+        startRes = endRes - horizontal;
       }
-      else
+      else if (horizontal < 0)
       {
-        transY = imgHeight - ((vertical + 1) * charHeight);
+        endRes = startRes - horizontal;
       }
-    }
-    else if (vertical < 0)
-    {
-      endSeq = startSeq - vertical;
+      else if (vertical > 0) // scroll down
+      {
+        startSeq = endSeq - vertical;
 
-      if (endSeq > ranges.getEndSeq())
+        if (startSeq < ranges.getStartSeq())
+        { // ie scrolling too fast, more than a page at a time
+          startSeq = ranges.getStartSeq();
+        }
+        else
+        {
+          transY = imgHeight - ((vertical + 1) * charHeight);
+        }
+      }
+      else if (vertical < 0)
       {
-        endSeq = ranges.getEndSeq();
+        endSeq = startSeq - vertical;
+
+        if (endSeq > ranges.getEndSeq())
+        {
+          endSeq = ranges.getEndSeq();
+        }
       }
-    }
 
-    gg.translate(transX, transY);
-    drawPanel(gg, startRes, endRes, startSeq, endSeq, 0);
-    gg.translate(-transX, -transY);
+      gg.translate(transX, transY);
+      drawPanel(gg, startRes, endRes, startSeq, endSeq, 0);
+      gg.translate(-transX, -transY);
 
-    repaint();
-    fastpainting = false;
+      repaint();
+    } finally
+    {
+      fastpainting = false;
+    }
   }
 
   @Override
@@ -1185,56 +1191,45 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
   {
     String eventName = evt.getPropertyName();
 
-    // if (av.getWrapAlignment())
-    // {
-    // if (eventName.equals(ViewportRanges.STARTRES))
-    // {
-    // repaint();
-    // }
-    // }
-    // else
-    {
-      int scrollX = 0;
-      if (eventName.equals(ViewportRanges.STARTRES))
+    int scrollX = 0;
+    if (eventName.equals(ViewportRanges.STARTRES))
+    {
+      // Make sure we're not trying to draw a panel
+      // larger than the visible window
+      ViewportRanges vpRanges = av.getRanges();
+      scrollX = (int) evt.getNewValue() - (int) evt.getOldValue();
+      int range = vpRanges.getEndRes() - vpRanges.getStartRes();
+      if (scrollX > range)
       {
-        // Make sure we're not trying to draw a panel
-        // larger than the visible window
-        ViewportRanges vpRanges = av.getRanges();
-        scrollX = (int) evt.getNewValue() - (int) evt.getOldValue();
-        int range = vpRanges.getEndRes() - vpRanges.getStartRes();
-        if (scrollX > range)
-        {
-          scrollX = range;
-        }
-        else if (scrollX < -range)
-        {
-          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.
-      if (eventName.equals(ViewportRanges.STARTRES))
+    // 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))
+    {
+      // scroll - startres and endres both change
+      if (av.getWrapAlignment())
       {
-        // scroll - startres and endres both change
-        if (av.getWrapAlignment())
-        {
-          fastPaintWrapped(scrollX);
-          // fastPaintWrapped(scrollX > 0 ? 1 : -1); // to debug: 1 at a time
-        }
-        else
-        {
-          fastPaint(scrollX, 0);
-        }
+        fastPaintWrapped(scrollX);
       }
-      else if (eventName.equals(ViewportRanges.STARTSEQ))
+      else
       {
-        fastPaint(0, (int) evt.getNewValue() - (int) evt.getOldValue());
+        fastPaint(scrollX, 0);
       }
     }
+    else if (eventName.equals(ViewportRanges.STARTSEQ))
+    {
+      fastPaint(0, (int) evt.getNewValue() - (int) evt.getOldValue());
+    }
   }
 
   /**
@@ -1252,36 +1247,48 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
     {
       /*
        * shift of more than one view width is 
-       * too complicated to handle in this method
+       * overcomplicated to handle in this method
        */
       fastPaint = false;
       repaint();
       return;
     }
 
-    fastPaint = true;
+    if (fastpainting || gg == null)
+    {
+      return;
+    }
 
-    /*
-     * relocate the regions of the alignment that are still visible
-     */
-    shiftWrappedAlignment(-scrollX);
+    fastPaint = true;
+    fastpainting = true;
 
-    /*
-     * add new columns (scale above, sequence, annotation)
-     * - at top left if scrollX < 0 
-     * - at right of last two widths if scrollX > 0
-     * also West scale top left or East scale bottom right if shown
-     */
-    if (scrollX < 0)
+    try
     {
-      fastPaintWrappedAddLeft(-scrollX);
-    }
-    else
+      /*
+       * relocate the regions of the alignment that are still visible
+       */
+      shiftWrappedAlignment(-scrollX);
+
+      /*
+       * add new columns (scale above, sequence, annotation)
+       * - at top left if scrollX < 0 
+       * - at right of last two widths if scrollX > 0
+       * also West scale top left or East scale bottom right if shown
+       */
+      if (scrollX < 0)
+      {
+        fastPaintWrappedAddLeft(-scrollX);
+      }
+      else
+      {
+        fastPaintWrappedAddRight(scrollX);
+      }
+
+      repaint();
+    } finally
     {
-      fastPaintWrappedAddRight(scrollX);
+      fastpainting = false;
     }
-
-    repaint();
   }
 
   /**
@@ -1317,18 +1324,21 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
     }
 
     /*
-     * limit visible widths to max widths of alignment
+     * limit visible widths to max widths of alignment, from the
+     * current start residue (we may be scrolled down)
      */
     ViewportRanges ranges = av.getRanges();
-    int visibleAlignmentWidth = ranges.getVisibleAlignmentWidth();
+    int availableAlignmentWidth = ranges.getVisibleAlignmentWidth()
+            - ranges.getStartRes();
     int viewportWidth = ranges.getViewportWidth();
-    int maxWidths = visibleAlignmentWidth / viewportWidth;
-    if (visibleAlignmentWidth % viewportWidth > 0)
+    int maxWidths = availableAlignmentWidth / viewportWidth;
+    if (availableAlignmentWidth % viewportWidth > 0)
     {
       maxWidths++;
     }
     visibleWidths = Math.min(visibleWidths, maxWidths);
-    int widthInColumns = (getWidth() - labelWidthEast - labelWidthWest)
+    int canvasWidth = getWidth();
+    int widthInColumns = (canvasWidth - labelWidthEast - labelWidthWest)
             / charWidth;
 
     /**
@@ -1392,7 +1402,7 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
      * scrolling right beyond end of alignment
      */
     gg.setColor(Color.white);
-    int width = getWidth() - labelWidthWest - xOffset;
+    int width = canvasWidth - labelWidthWest - xOffset;
     gg.fillRect(labelWidthWest, ypos - hgap, width, repeatHeight);
 
     gg.setFont(av.getFont());
@@ -1410,6 +1420,17 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
     {
       drawVerticalScale(gg, leftEndColumn, endRes, ypos, false);
     }
+
+    /*
+     * and finally, white fill any space below the visible alignment
+     * (in case it has wrapped to just the top part of the panel)
+     */
+    int heightBelow = canvasHeight - visibleWidths * repeatHeight;
+    if (heightBelow > 0)
+    {
+      gg.setColor(Color.white);
+      gg.fillRect(0, canvasHeight - heightBelow, canvasWidth, heightBelow);
+    }
   }
 
   /**
@@ -1484,6 +1505,8 @@ public class SeqCanvas extends JComponent implements ViewportListenerI
     {
       visibleWidths++;
     }
+    // todo limit visibleWidths to not exceed width of alignment
+    // (don't process white space below)
 
     if (positions > 0)
     {