JAL-1118 - hack to try and get rid of flicker. consider moving greyed out image rende...

diff --git a/src/jalview/gui/AnnotationPanel.java b/src/jalview/gui/AnnotationPanel.java
index 85a31f7..03fbf28 100755 (executable)
--- a/src/jalview/gui/AnnotationPanel.java
+++ b/src/jalview/gui/AnnotationPanel.java
@@ -809,7 +809,7 @@ public class AnnotationPanel extends JPanel implements AwtRenderPanelI,
     repaint();
 
   }
-
+  private volatile boolean lastImageGood=false;
   /**
    * DOCUMENT ME!
    *
@@ -822,18 +822,21 @@ public class AnnotationPanel extends JPanel implements AwtRenderPanelI,
    */
   public void drawComponent(Graphics g, int startRes, int endRes)
   {
+    BufferedImage oldFaded=fadedImage;
     if (av.isCalcInProgress())
     {
       if (image == null)
       {
+        lastImageGood=false;
         return;
       }
       // We'll keep a record of the old image,
       // and draw a faded image until the calculation
       // has completed
-      if (fadedImage == null || fadedImage.getWidth() != imgWidth
-              || fadedImage.getHeight() != image.getHeight())
+      if (lastImageGood && (fadedImage == null || fadedImage.getWidth() != imgWidth
+              || fadedImage.getHeight() != image.getHeight()))
       {
+//        System.err.println("redraw faded image ("+(fadedImage==null ? "null image" : "") + " lastGood="+lastImageGood+")");
         fadedImage = new BufferedImage(imgWidth, image.getHeight(),
                 BufferedImage.TYPE_INT_RGB);
 
@@ -847,10 +850,16 @@ public class AnnotationPanel extends JPanel implements AwtRenderPanelI,
         fadedG.drawImage(image, 0, 0, this);
 
       }
+      // make sure we don't overwrite the last good faded image until all calculations have finished
+      lastImageGood=false;
 
     }
     else
     {
+      if (fadedImage!=null)
+      {
+        oldFaded=fadedImage;
+      }
       fadedImage = null;
     }
 
@@ -876,7 +885,11 @@ public class AnnotationPanel extends JPanel implements AwtRenderPanelI,
 
       return;
     }
-    renderer.drawComponent(this, av, g, activeRow, startRes, endRes);
+    lastImageGood = renderer.drawComponent(this, av, g, activeRow, startRes, endRes);
+    if (!lastImageGood && fadedImage==null)
+    {
+      fadedImage=oldFaded;
+    }
   }
 
   @Override