Double Buffer

				
//**************************************
// Name: Double Buffer
// Description:Demonstates the use of off screen graphics for smoother animation.
// By: Dave Smith
//
//This code is copyrighted and has// limited warranties.Please see http://www.Planet-Source-Code.com/vb/scripts/ShowCode.asp?txtCodeId=1862&lngWId=2//for details.//**************************************

import java.applet.Applet;
import java.awt.*;
import java.lang.*;
public class DoubleBuffer extends Applet implements Runnable{
	private Image offScreenImage;
	int holdX[];
	int holdY[];
	int holdRad[];
	Thread thisThread = new Thread(this);
	int intThrow = 0;
	int intSpeed = 1;
	public void init() {
		setBackground(Color.black);
		offScreenImage = createImage(getSize().width, getSize().height);
		holdX = new int[200];
		holdY = new int[200];
		holdRad = new int[200];
		for (int count=0;count<200;count++) {
			holdX[count] = (int)(getSize().width*Math.random());
			holdY[count] = (int)(getSize().height*Math.random());
			holdRad[count] = (int)(4*Math.random());
		}
		repaint();
		thisThread.start();
	}
	public void update(Graphics g) {
		Graphics offScreenGraphics = offScreenImage.getGraphics();	
		offScreenGraphics.setColor(Color.black);
		offScreenGraphics.fillRect(0,0,getSize().width, getSize().height);
		offScreenGraphics.setColor(Color.white);
		for (int count=0;count<200;count++) {
			offScreenGraphics.fillRect(holdX[count], holdY[count], holdRad[count], holdRad[count]);
			holdX[count] += holdRad[count]+intSpeed;
			if (holdRad[count] <= 1) {
				offScreenGraphics.setColor(Color.white);
			} else {
				offScreenGraphics.setColor(Color.white);
			}
			if (holdX[count]>=getSize().width) {
				holdX[count] = 1;
			}
			if (holdX[count] < 0) {
				holdX[count] = getSize().width;
			}
		}
		paint(offScreenGraphics);
		g.drawImage(offScreenImage,0,0,this);
	}
	public void run() {		
		do {
			repaint();
			try {
				Thread.currentThread().sleep(15);
			} catch (Exception sleepProblem) {			// Slow the bugger down a bit.
				System.out.println(sleepProblem);
			}	
		} while (intThrow==0);
	}
	public boolean keyDown(Event event, int keyCode) {
		if (event.shiftDown()) {
			intSpeed+=1;
		}
		if (event.controlDown()) {
			intSpeed-=1;
		}
		return true;
	}
}