JAL-3444 translucent overview

- was missing 2nd isJS block
- JS was setting pixel background to white instead of defaultColour
prior to transparent color painting

diff --git a/src/jalview/renderer/seqfeatures/FeatureColourFinder.java b/src/jalview/renderer/seqfeatures/FeatureColourFinder.java
index ee40d83..836bc4a 100644 (file)
--- a/src/jalview/renderer/seqfeatures/FeatureColourFinder.java
+++ b/src/jalview/renderer/seqfeatures/FeatureColourFinder.java
@@ -98,11 +98,17 @@ public class FeatureColourFinder
      */
     if (featureRenderer.getTransparency() != 1f)
     {
-      g = goff;
-      if (defaultColour != null)
+      Color c = (defaultColour == null ? Color.white : defaultColour);
+      if (Platform.isJS())
       {
-        offscreenImage.setRGB(0, 0, defaultColour.getRGB());
+        g = goff;
+        // Clear the HTML5 canvas color.
+        // otherwise we get a smearing.
+        // For whatever reason, this is necessary BH 2019.10.01.
+        g.setColor(c);
+        g.fillRect(0, 0, 1, 1);
       }
+      offscreenImage.setRGB(0, 0, c.getRGB());
     }
 
     Color c = featureRenderer.findFeatureColour(seq, column + 1, g);