JAL-2388 Add missed optimisation

[jalview.git] / src / jalview / renderer / OverviewRenderer.java

diff --git a/src/jalview/renderer/OverviewRenderer.java b/src/jalview/renderer/OverviewRenderer.java
index 69676c8..9291ca6 100644 (file)
--- a/src/jalview/renderer/OverviewRenderer.java
+++ b/src/jalview/renderer/OverviewRenderer.java
@@ -95,20 +95,27 @@ public class OverviewRenderer
                 Math.round((colIndex + 1) * pixelsPerCol) - 1,
                 miniMe.getWidth() - 1);
 
-        // determine the colour based on the sequence and column position
-        rgbcolor = getColumnColourFromSequence(seq,
-                hidden || cols.isHidden(alignmentCol), alignmentCol, finder);
-
-        // fill in the appropriate number of pixels
-        for (int row = pixelRow; row <= endRow; ++row)
+        // don't do expensive colour determination if we're not going to use it
+        // NB this is important to avoid performance issues in the overview
+        // panel
+        if (pixelCol <= endCol)
         {
-          for (int col = pixelCol; col <= endCol; ++col)
+          // determine the colour based on the sequence and column position
+          rgbcolor = getColumnColourFromSequence(seq,
+                  hidden || cols.isHidden(alignmentCol), alignmentCol,
+                  finder);
+
+          // fill in the appropriate number of pixels
+          for (int row = pixelRow; row <= endRow; ++row)
           {
-            miniMe.setRGB(col, row, rgbcolor);
+            for (int col = pixelCol; col <= endCol; ++col)
+            {
+              miniMe.setRGB(col, row, rgbcolor);
+            }
           }
-        }
 
-        pixelCol = endCol + 1;
+          pixelCol = endCol + 1;
+        }
         colIndex++;
       }
       pixelRow = endRow + 1;