Ticket #685: josm-render-speedup.diff

home/dnaber/workspace/JOSM/src/org/openstreetmap/josm/gui/layer/OsmDataLayer.java

@@ -10 +10 @@
 import java.awt.Graphics;
 import java.awt.GridBagLayout;
 import java.awt.Point;
+import java.awt.Transparency;
 import java.awt.event.ActionEvent;
+import java.awt.image.BufferedImage;
 import java.io.File;
 import java.util.Collection;
 import java.util.HashSet;
@@ -170 +172 @@
                 }
                 else
                 {
-                        standardMapPainter.setGraphics(g);
+                        // MapPaintVisitor paints calls fillPolygon() with an alpha
+                        // channel -- this is slow, speed it up by rendering to a BufferedImage:
+                        BufferedImage bim = new BufferedImage(mv.getWidth(), mv.getHeight(), Transparency.OPAQUE);
+                        standardMapPainter.setGraphics(bim.createGraphics());
                         standardMapPainter.setNavigatableComponent(mv);
                         standardMapPainter.inactive = inactive;
                         standardMapPainter.visitAll(data);
+                        g.drawImage(bim, 0, 0, null);
                 }
                 Main.map.conflictDialog.paintConflicts(g, mv);
         }