289 - Volatile Image Renderer

//
//  VolatileImageRenderer.java
//  SwingEasel
//
//  Created by Philip Rhodes on 8/20/05.
//  Copyright 2005 Philip J Rhodes. All rights reserved.
//

import java.awt.*;
import java.awt.image.*;

/** This abstract class provides a VolatileImage for double buffering. Although
 *  Swing provides double buffering by default, using a VolatileImage allows
 *  the Java Virtual Machine (JVM) to take advantage of hardware acceleration.
 *  Even if a particular JVM doesn't do this, or if there is no 3D graphics card
 *  installed, there may still be an advantage to using an image, because each
 *  drawing operation may be slightly faster.
 */
public abstract class VolatileImageRenderer extends ImageRenderer{

   /** Create a VolatileImageRenderer to render the shapes in the World w.*/
   VolatileImageRenderer(World w, int width, int height, boolean showFPS){

      super(w, width, height, showFPS);
   }

   /** Creates the Volatile image and associated Graphics object. The image
    *  takes its dimensions from the size of the JPanel. (Remember that this
    *  class is a child of JPanel.  IMPORTANT NOTE: The JPanel must be visible
    *  when this method is called. So, call setVisible(true) BEFORE calling
    *  init(). Even if you do this, there may be a race condition if your JVM
    *  uses a separate thread to schedule repaints. Because of this, the init()
    *  method will loop until it succeeds in creating a volatile image.
    */
   public void init(){

      do {

         this.backingImage = createVolatileImage(this.imageWidth, this.imageHeight);

      } while(this.backingImage == null);

      this.imageGraphics = this.backingImage.getGraphics();
   }


   public void render(){

      if(this.imageGraphics == null){

         this.init();
      }

   }


}