use volatile image to optimize

diylc/diylc-swing/src/org/diylc/swing/plugins/cloud/view/browser/CloudGlassPane.java

@@ -3,7 +3,10 @@ package org.diylc.swing.plugins.cloud.view.browser;
 import java.awt.Color;
 import java.awt.Cursor;
 import java.awt.FontMetrics;
+import java.awt.Graphics;
 import java.awt.Graphics2D;
+import java.awt.GraphicsConfiguration;
+import java.awt.GridBagLayout;
 import java.awt.Image;
 import java.awt.Rectangle;
 import java.awt.RenderingHints;
@@ -13,6 +16,7 @@ import java.awt.event.KeyEvent;
 import java.awt.event.KeyListener;
 import java.awt.event.MouseEvent;
 import java.awt.event.MouseListener;
+import java.awt.image.VolatileImage;
 
 import javax.swing.JPanel;
 import javax.swing.Timer;
@@ -32,15 +36,21 @@ public class CloudGlassPane extends JPanel implements MouseListener, KeyListener
 
   private long startTime;
   private final int msPerPx = 6;
+  private final Color bgColor = new Color(192, 222, 237);
 
   private Timer animationTimer;
 
+  private VolatileImage volatileImg;
+
   public CloudGlassPane() {
     addKeyListener(this);
     addMouseListener(this);
     setCursor(new Cursor(Cursor.WAIT_CURSOR));
     setOpaque(false);
-    setBackground(new Color(192, 222, 237));
+    setBackground(bgColor);
+
+    setLayout(new GridBagLayout());
+
 
     animationTimer = new Timer(20, new ActionListener() {
 
@@ -61,14 +71,35 @@ public class CloudGlassPane extends JPanel implements MouseListener, KeyListener
     super.setVisible(aFlag);
   };
 
+  private void createBackBuffer() {
+    GraphicsConfiguration gc = getGraphicsConfiguration();
+    volatileImg = gc.createCompatibleVolatileImage(getWidth(), getHeight());
+  }
+
   @Override
   public void paint(java.awt.Graphics g) {
-    Graphics2D g2d = (Graphics2D) g;
-    // g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.8f));
 
+    createBackBuffer();
+
+    do {
+
+      // Validate the volatile image for the graphics configuration of this
+      // component. If the volatile image doesn't apply for this graphics configuration
+      // (in other words, the hardware acceleration doesn't apply for the new device)
+      // then we need to re-create it.
+      GraphicsConfiguration gc = this.getGraphicsConfiguration();
+      int valCode = volatileImg.validate(gc);
+
+      // This means the device doesn't match up to this hardware accelerated image.
+      if (valCode == VolatileImage.IMAGE_INCOMPATIBLE) {
+        createBackBuffer(); // recreate the hardware accelerated image.
+      }
+
+      Graphics offscreenGraphics = volatileImg.getGraphics();
+      Graphics2D g2d = (Graphics2D) offscreenGraphics;
       Image cloud = IconLoader.CloudBg.getImage();
 
-    g2d.setColor(new Color(192, 222, 237));
+      g2d.setColor(bgColor);
       g2d.fillRect(0, cloud.getHeight(null), getWidth(), getHeight());
 
       g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
@@ -87,8 +118,13 @@ public class CloudGlassPane extends JPanel implements MouseListener, KeyListener
       Rectangle rect = new Rectangle(getSize());
       int x = (rect.width - metrics.stringWidth(text)) / 2;
       int y = ((rect.height - metrics.getHeight()) / 2) + metrics.getAscent();
-    g.drawString(text, x, y);
+      g2d.drawString(text, x, y);
-  };
+
+      // paint back buffer to main graphics
+      g.drawImage(volatileImg, 0, 0, this);
+      // Test if content is lost
+    } while (volatileImg.contentsLost());
+  }
 
   @Override
   public void mouseClicked(final MouseEvent pArg0) {}