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

[Deepak Bhole]

* Deepak Bhole <dbhole at redhat.com> [2010-11-03 10:52]:
> * Omair Majid <omajid at redhat.com> [2010-11-03 09:32]:
> > Hi Deepak,
> > 
> > On 11/02/2010 05:37 PM, Deepak Bhole wrote:
> > >* Deepak Bhole<dbhole at redhat.com>  [2010-11-02 17:31]:
> > >>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.
> > >>
> > 
> > Is there a specific test case that this fixes? The only flickering
> > applet that I know of is at
> > http://download.oracle.com/javase/1.4.2/docs/guide/misc/applet.html,
> > and I dont see any change in that applet with the patch applied.
> > 
> 
> Nope, no specific applet. I came across the problem when I was working
> on a splash screen for the plugin -- it flickers significantly without
> the patch.
> 
> Applets which do something similar would flicker as well (the splash
> screen is embedded into the same frame that the plugin would be).
> 

s/plugin would be/applet would be

> Deepak
> 
> > >>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
> > >
> > >
> > >Doh! There shouldn't be a println in there. New patch attached. I also
> > >fixed the variable names for the image and its graphics.
> > >
> > >
> > >>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);
> > 
> > The overridden method is update, but paint is called here instead.
> > Is there a reason for that? As far as I know, the semantics of
> > update() are slightly different from paint() - update() clears the
> > background and then calls paint(). Perhaps super.update() might be
> > more appropriate?
> > 
> > >>+
> > >>+    	 // Draw the painted image
> > >>+    	 g.drawImage(bufferedPanelImage, 0, 0, this);
> > >>+     }
> > >>   }
> > >
> > 
> > Thanks,
> > Omair