src/share/classes/javax/swing/RepaintManager.java

*** 117,126 ****
--- 117,131 ----
      private static final Object repaintManagerKey = RepaintManager.class;
  
      // Whether or not a VolatileImage should be used for double-buffered painting
      static boolean volatileImageBufferEnabled = true;
      /**
+      * Type of VolatileImage which should be used for double-buffered
+      * painting.
+      */
+     private static final int doubleBufferType;
+     /**
       * Value of the system property awt.nativeDoubleBuffering.
       */
      private static boolean nativeDoubleBuffering;
  
      // The maximum number of times Swing will attempt to use the VolatileImage
*** 202,211 ****
--- 207,223 ----
                  getLocalGraphicsEnvironment();
          if (ge instanceof SunGraphicsEnvironment) {
              ((SunGraphicsEnvironment)ge).addDisplayChangedListener(
                      new DisplayChangedHandler());
          }
+         Toolkit tk = Toolkit.getDefaultToolkit();
+         if ((tk instanceof SunToolkit)
+                 && ((SunToolkit) tk).isSwingBackbufferTranslucencySupported()) {
+             doubleBufferType = Transparency.TRANSLUCENT;
+         } else {
+             doubleBufferType = Transparency.OPAQUE;
+         }
      }
  
      /**
       * Return the RepaintManager for the calling thread given a Component.
       *
*** 987,997 ****
          if (image == null || image.getWidth() < width ||
                               image.getHeight() < height) {
              if (image != null) {
                  image.flush();
              }
!             image = config.createCompatibleVolatileImage(width, height);
              volatileMap.put(config, image);
          }
          return image;
      }
  
--- 999,1010 ----
          if (image == null || image.getWidth() < width ||
                               image.getHeight() < height) {
              if (image != null) {
                  image.flush();
              }
!             image = config.createCompatibleVolatileImage(width, height,
!                                                          doubleBufferType);
              volatileMap.put(config, image);
          }
          return image;
      }
  
*** 1481,1493 ****
--- 1494,1521 ----
              try {
                  for(x = clipX, maxx = clipX+clipW; x < maxx ;  x += bw ) {
                      for(y=clipY, maxy = clipY + clipH; y < maxy ; y += bh) {
                          osg.translate(-x, -y);
                          osg.setClip(x,y,bw,bh);
+                         if (doubleBufferType != Transparency.OPAQUE
+                                 && osg instanceof Graphics2D) {
+                             Graphics2D g2d = (Graphics2D) osg.create();
+                             g2d.setBackground(c.getBackground());
+                             g2d.clearRect(x, y, bw, bh);
+                             g2d.dispose();
+                         }
                          c.paintToOffscreen(osg, x, y, bw, bh, maxx, maxy);
                          g.setClip(x, y, bw, bh);
+                         if (doubleBufferType != Transparency.OPAQUE
+                                 && osg instanceof Graphics2D) {
+                             Graphics2D g2d = (Graphics2D) g.create();
+                             g2d.setComposite(AlphaComposite.Src);
+                             g2d.drawImage(image, x, y, c);
+                             g2d.dispose();
+                         } else {
                              g.drawImage(image, x, y, c);
+                         }
                          osg.translate(x, y);
                      }
                  }
              } finally {
                  osg.dispose();