《Java2图形设计卷II：Swing》配套光盘源码

				import javax.swing.*;
				import java.awt.*;
				import java.awt.event.*;
				import java.io.*;
				
				public class Test extends JFrame {
					AnimationPane p = new AnimationPane();
				
					public Test() {
						super("Swing Double Buffering");
						getContentPane().add(p, "Center");
				
						addMouseListener(new MouseAdapter() {
							public void mousePressed(MouseEvent e) {
								if(p.isRunning()) 	p.stop();
								else				p.start();
							}
						});
					}
					public static void main(String args[]) {
						final Frame f = new Test();
						f.setBounds(100,100,300,300);
						f.setVisible(true);
				
						f.addWindowListener(new WindowAdapter() {
							public void windowClosing(WindowEvent event) {
								f.dispose();
								System.exit(0);
							}
						});
					}
				}
				class AnimationPane extends JPanel implements ActionListener {
					Icon[]		icons		= new Icon[4];
					int			iconIndex	= 0;
					Point 		ulhc 		= new Point(0,0);
					Point		moveVector 	= new Point(1,1);
					Timer 		moveTimer 	= new Timer(5, this);
					Timer 		spinTimer 	= new Timer(125, this);
					Dimension 	imsz;
				
					public AnimationPane() {
						setDoubleBuffered(true);
						setOpaque(true);
				
						icons[0] = new ImageIcon("baseball.gif");
						icons[1] = new ImageIcon("baseball_90.gif");
						icons[2] = new ImageIcon("baseball_180.gif");
						icons[3] = new ImageIcon("baseball_270.gif");
				
						imsz = new Dimension(icons[0].getIconWidth(),
											icons[1].getIconHeight());
						start();
					}
					synchronized public void paint(Graphics g) {
						Dimension 		size = getSize();
						RepaintManager 	rm = RepaintManager.currentManager(this);
						Image 			off = rm.getOffscreenBuffer(this, 
																	size.width,
																	size.height);
						Graphics og = off.getGraphics();
						Rectangle cr = (Rectangle)g.getClip();
				
						if(cr.width != size.width || cr.height != size.height) {
							g.drawImage(off,0,0,this);
							return;
						}
						try {
							Rectangle oldr = 
										new Rectangle(ulhc.x,ulhc.y,
													imsz.width,imsz.height);
							og.setColor(getBackground());
							og.fillRect(ulhc.x, ulhc.y, imsz.width, imsz.height);
				
							checkForEdgeCollision(size);
							ulhc.x += moveVector.x;
							ulhc.y += moveVector.y;
				
							icons[iconIndex].paintIcon(this, og, ulhc.x, ulhc.y);
						
							Rectangle union, newr = new Rectangle(ulhc.x,ulhc.y,
														imsz.width,imsz.height);
				
							union = oldr.union(newr);
							og.setColor(getBackground());
				
							g.setClip(union.x,union.y,union.width,union.height);
							g.drawImage(off,0,0,this);
						}
						finally {
							og.dispose();
						}
					}
					public void actionPerformed(ActionEvent event) {
						Timer t = (Timer)event.getSource();
				
						if(t == spinTimer)
							iconIndex = iconIndex == icons.length-1 ? 
															0 : iconIndex+1;
						repaint();
					}
					public void stop() {
						moveTimer.stop();
						spinTimer.stop();
					}
					public void start() {
						moveTimer.start();
						spinTimer.start();
					}
					public boolean isRunning() {
						return moveTimer.isRunning() && spinTimer.isRunning();
					}
					public void update(Graphics g) {
						paint(g);
					}
					private void checkForEdgeCollision(Dimension size) {
						if(ulhc.x + imsz.width + moveVector.x > size.width ||
												 ulhc.x + moveVector.x < 0)
							moveVector.x -= moveVector.x*2;
						if(ulhc.y + imsz.height + moveVector.y > size.height ||
												  ulhc.y + moveVector.y < 0)
							moveVector.y -= moveVector.y*2;
					}
				}