[icedtea-web] RFC: Patch to double-buffer applets

[Deepak Bhole]

Hi,

IcedTea plugin currently does not double-buffer the applet panel. As a
result, some applets may flicker depending on the machine.

Attached patch buffers the frame offscreen and then draws it, thereby
addressing the issue.

ChangeLog:
2010-11-02  Deepak Bhole <dbhole at redhat.com>

   * plugin/icedteanp/java/sun/applet/PluginAppletViewer.java (update):
   Override method and implement double-buffering.

Cheers,
Deepak
-------------- next part --------------
diff -r 6c2527d42900 ChangeLog
--- a/ChangeLog	Mon Nov 01 11:44:15 2010 -0400
+++ b/ChangeLog	Tue Nov 02 17:29:03 2010 -0700
@@ -1,3 +1,8 @@
+2010-11-02  Deepak Bhole <dbhole at redhat.com>
+
+	* plugin/icedteanp/java/sun/applet/PluginAppletViewer.java (update):
+	Override method and implement double-buffering.
+
 2010-11-01  Omair Majid  <omajid at redhat.com>
 
 	* Makefile.am (clean-IcedTeaPlugin): Only delete launcher directory if it
diff -r 6c2527d42900 NEWS
--- a/NEWS	Mon Nov 01 11:44:15 2010 -0400
+++ b/NEWS	Tue Nov 02 17:29:03 2010 -0700
@@ -12,3 +12,4 @@
 
 * Initial release of IcedTea-Web
 * PR542: Plugin fails with NPE on http://www.openprocessing.org/visuals/iframe.php?visualID=2615
+* Applets are now double-buffered to eliminate flicker in ones that do heavy drawing
diff -r 6c2527d42900 plugin/icedteanp/java/sun/applet/PluginAppletViewer.java
--- a/plugin/icedteanp/java/sun/applet/PluginAppletViewer.java	Mon Nov 01 11:44:15 2010 -0400
+++ b/plugin/icedteanp/java/sun/applet/PluginAppletViewer.java	Tue Nov 02 17:29:03 2010 -0700
@@ -359,6 +366,9 @@
 
      private static Long requestIdentityCounter = 0L;
      
+     private Image bufferedPanelImage;
+     private Graphics bufferedImageGraphics;
+     
      /**
       * Null constructor to allow instantiation via newInstance()
       */
@@ -2163,4 +2178,24 @@
         }
     }
      }
+
+     /**
+      * {@inheritDoc}
+      */
+     public void update(Graphics g) {
+
+    	 System.err.println("Buffering and drawing");
+    	 
+    	 // If the image or the graphics don't exist, create new ones
+    	 if (bufferedPanelImage == null || bufferedImageGraphics == null) {
+    		 bufferedPanelImage = createImage(getWidth(), getHeight());
+    		 bufferedImageGraphics = bufferedPanelImage.getGraphics ();
+    	 }
+
+    	 // Paint off-screen
+    	 paint(bufferedImageGraphics);
+
+    	 // Draw the painted image
+    	 g.drawImage(bufferedPanelImage, 0, 0, this);
+     }
  }