X-Git-Url: http://source.jalview.org/gitweb/?a=blobdiff_plain;f=src%2Fjalview%2Frenderer%2Fseqfeatures%2FFeatureColourFinder.java;h=136404b86e61939dc1c9c6221cdff386cd6c23f8;hb=5e37267b48b75b90d264e7ab04ae1bc4a0155e3e;hp=8da880a60b01a9f07e433c402006e287daa248b2;hpb=113cc13d931734b2fc55e4b13474b6c863008e12;p=jalview.git

diff --git a/src/jalview/renderer/seqfeatures/FeatureColourFinder.java b/src/jalview/renderer/seqfeatures/FeatureColourFinder.java
index 8da880a..136404b 100644
--- a/src/jalview/renderer/seqfeatures/FeatureColourFinder.java
+++ b/src/jalview/renderer/seqfeatures/FeatureColourFinder.java
@@ -23,6 +23,7 @@ package jalview.renderer.seqfeatures;
 import jalview.api.FeatureRenderer;
 import jalview.api.FeaturesDisplayedI;
 import jalview.datamodel.SequenceI;
+import jalview.util.Platform;
 import jalview.viewmodel.seqfeatures.FeatureRendererModel;
 
 import java.awt.Color;
@@ -134,10 +135,16 @@ public class FeatureColourFinder
     if (featureRenderer.getTransparency() != 1f)
     {
       g = goff;
-      if (defaultColour != 0)
+      int c = (defaultColour == 0 ? -1 : defaultColour);
+      if (Platform.isJS())
       {
-        offscreenImage.setRGB(0, 0, defaultColour);
+        // Clear the HTML5 canvas color.
+        // otherwise we get a smearing.
+        // For whatever reason, this is necessary BH 2019.10.01.
+        g.setColor(new Color(c));
+        g.fillRect(0, 0, 1, 1);
       }
+      offscreenImage.setRGB(0, 0, c);
     }
 
     Color c = featureRenderer.findFeatureColour(seq, column + 1, g);
@@ -148,6 +155,12 @@ public class FeatureColourFinder
 
     if (g != null)
     {
+      if (Platform.isJS())
+      {
+        // for JavaScript the pixel itself
+        // is a resource that needs to be recreated in getRGB(0,0)
+        offscreenImage.flush();
+      }
       return offscreenImage.getRGB(0, 0);
     }
     return c.getRGB();