serialimage2.java

裁减一个图象的部分

import java.awt.*;
import java.applet.*;

public class SerialImage2 extends Applet implements Runnable
{
	int SPF;//动画播放发帧数的倒数
	int sx,sy; //图象来源区域
	Image animation;
	MediaTracker mt ;
	Thread newThread;
	Image offScreen;//次画面
	Graphics drawOffScreen;//绘制次画面的Graphics
	
	public void init()
	{
		SPF = 100;
		mt = new MediaTracker(this);
		animation = getImage(getDocumentBase(), "images/cg0432.gif");
		mt.addImage(animation, 0);
		try
		{
			showStatus("图象加载中...");
			mt.waitForAll();	
		}	
		catch (InterruptedException e) {}
		
		offScreen = createImage(250, 250);//建立次画面
		drawOffScreen = offScreen.getGraphics();
	}	
	
	public void start()
	{
		//建立并启动新线程
		newThread = new Thread(this);
		newThread.start();	
	}
	public void stop()
	{
		newThread = null;
	}
	
	public void paint(Graphics g)
	{
		//下面清除次画面
		drawOffScreen.clearRect(0, 0, 250, 250);
		
		//在次画面绘制图象
		drawOffScreen.drawImage(animation, 0, 0, 250, 250, 
								sx, sy, sx + 250, sy + 250,this);	
		g.drawImage(offScreen, 0, 0, 250, 250, this);
	}
	public void update(Graphics g)
	{
		paint(g);	
	}
	public void run()
	{
		while (newThread != null)
		{
			repaint();
			try
			{
				Thread.sleep(SPF);
				//计算来源区域
				//下面是原始的，因为图片有更改，所以自己写一段
//				sx += 128;
//				if (sx == 640)
//				{
//					sy += 96;
//					sx = 0;
//					if (sy == 480)
//						sy = 0;	
//				}	
				sx += 250;
				if (sx == 1750)
					sx = 0;
			}	
			catch (InterruptedException e) {}
		}	
	}
}