laserpic.java

激光绘图, 这个小例子简单易懂,是初学applet的好例子,欢迎下载

import java.applet.*;
import java.awt.*;
import java.awt.image.*;
import java.util.*;

public class LaserPic extends Applet
{
	private Image image;
	private int x = 25,y = 25;
	private Random random;
	private int width,height,w,h,image_size,pixels[];

	public void init()
	{
		random=new Random();
		String imageName=getParameter("Image");
		image=getImage(getDocumentBase(),imageName);
		MediaTracker imageTracker=new MediaTracker(this);
		imageTracker.addImage(image,0);
		try
		{
			imageTracker.waitForID(0);
		}
		catch (InterruptedException e)
		{
		
		}
	}

	public void start()
	{
		width=getSize().width;
		height=getSize().height;
		w=image.getWidth(this);
		h=image.getHeight(this);
		x = (width - w)/2;
		y = (height - h)/2; 
		image_size=w*h;
		pixels=new int[image_size];
		PixelGrabber pg=new PixelGrabber(image,0,0,w,h,pixels,0,w);
		try
		{
			pg.grabPixels();
		}
		catch (InterruptedException e)
		{
		
		}
	}
	
	public void paint(Graphics g)
	{
		g.setColor(Color.white);
		g.fillRect(0,0,getSize().width,getSize().height);
		drawImage(g,image,x,y);
	}

	private void drawImage(Graphics g,Image image,int x,int y)
	{
		while(true)
		{     
			g.setColor(Color.white);
			g.fillRect(0,0,getSize().width,getSize().height);
			try
			{
				int one_time=w;
				int S_x=0,S_y=0;
				S_x=(int)(random.nextFloat()*width);
				S_y=(int)(random.nextFloat()*height);
				Laser[] nextlot=new Laser[one_time];
				int k=0,l=0;
				int step=1,start=0;
				float f=random.nextFloat();
				step=(f<0.8)?34759:(f<0.9?1:image_size-1);
				start=(int)(random.nextFloat()*image_size);
				f=random.nextFloat();
				start=(f<0.5)?image_size:0;
				int sofar=0;
				for (k=start;l<image_size;l++,k+=step)
				{	
					Thread.sleep(2);
					if (k<0) k+=image_size;
					k%=image_size;
					int row=k/w;
					int col=k%w;
					Color colr=new Color(pixels[k]);
					int finishx=x+col;
					int y1=y+row;
					nextlot[sofar]=new Laser(colr,new Point(S_x,S_y),new Point(finishx,y1));
					sofar++;
					if (sofar==one_time)
					{
						Track(g,nextlot);
						sofar=0;
					}
				}
			}
			catch (Exception e)
			{
			
			}
			g.setPaintMode();
			g.drawImage(image,x,y,this);
			try
			{
				Thread.sleep(2000);
			}
			catch (InterruptedException e)
			{
			
			}
		}
	}

	private synchronized void Track(Graphics g,Laser[] nextlot)
	{
		Color back=Color.white;
		g.setXORMode(back);
		for (int pass=0;pass<2;pass++)
		{
			for (int pixnr=0;pixnr<nextlot.length;pixnr++)
			{
				Laser p=nextlot[pixnr];
				if (!close(p.c,back))
				{
					g.setColor(p.c);
					g.drawLine(p.start.x,p.start.y,p.finish.x,p.finish.y);
				}
				if (pass==1)
				{
					g.setColor(p.c);
					g.drawLine(p.finish.x,p.finish.y,p.finish.x,p.finish.y);
				}
			}
		}
		Thread.yield();
	}

	private boolean close(Color c1,Color c2)
	{
		return (Math.abs(c1.getRed()-c2.getRed()) + Math.abs(c1.getGreen()-c2.getGreen()) + 
                                                           Math.abs(c1.getBlue()-c2.getBlue()))<0xff;
	}
}

class Laser
{
	public Color c;
	public Point start,finish;
	
	public Laser(Color c,Point start,Point finish)
	{
		this.c=c;
		this.start=start;
		this.finish=finish;
	}
}