applet1.java

矩阵乘法的计算程序

import java.awt.*;
import java.applet.*;
import java.awt.image.*;
/**
 * This class reads PARAM tags from its HTML host page and sets
 * the color and label properties of the applet. Program execution
 * begins with the init() method. 
 */
public class Applet1 extends Applet
{
	Image img;
	boolean loaded;
	public void init()
	{
		img=getImage(getDocumentBase(),"bg.jpg");
		loaded=false;
	
	}

	

	public void paint(Graphics g){
		System.out.println("in paint:image width"+img.getWidth(this));
		System.out.println("in paint:image height"+img.getHeight(this));
		///g.drawImage(img,20,20,this);
		Handler handler=new Handler();
		handler.applet=this;
		g.drawImage(img,0,0,handler);
	}
}

class Handler implements ImageObserver{
	Applet applet;
	public boolean imageUpdate(Image img,int info,int x,int y,int width,int height){
		boolean first=true;
		if ((info&WIDTH)==0)
			System.out.println("image width not available,current width "+width);
		else
			System.out.println("image width available,current width "+width);
		if ((info&ERROR)==0 && (info&ABORT)==0)
			System.out.println("no error now");
		else{
			System.out.println("error occur and abort");
			return false;
		}
		if ((info&ALLBITS)==0){
			System.out.println("image are loading");
			return true;
		}else{
			System.out.println("image has been loaded");
			applet.repaint();
			return false;
		}
			
	}
}