Bewegte Animation

/*
 *
 * Copyright (c) 1996 - 1998
 * Frank Buss (fb@frank-buss.de), Stephan Schloepke (stephan@nordrhein.net)
 *
 * This applet was published in the book:
 *
 *     "Programmier Training Java, In 15 Stunden topfit"
 *     ISBN 3-8158-1303-4
 *     Authors: Frank Buss, Stephan Schloepke
 *     Data Becker Verlage (http://www.databecker.de)
 *
 * You can get this applet and more at http://www.frank-buss.de
 *
 */

//
// Animation - Beispiel Applet für Animationen mit Thread, 
//              Double-Buffering und Daumenkinoeffekt
//

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

public class Animation extends Applet implements Runnable {
        int X, Y;
        double SinX=0.0, SinY=0.0;
        double SinOffX=1 * Math.PI / 180, SinOffY=3 * Math.PI / 180;
        Thread Anim;
        private Image Buffer;
        private Graphics gBuffer;
        private Image Kugeln[];
        private int KugelNr=0;
        private int WarteZähler=0;

        public void start() {
                if (Anim == null) {
                        Anim = new Thread (this);
                        Anim.start();
                }
        }
        public void stop() {
                if (Anim != null) {
                        Anim.stop();
                        Anim = null;
                }
        }
       public void run() {
                while (true) {
                        try {
                                Anim.sleep (10);
                        } catch (Exception e) { }
                        repaint();
                }
        }
        public void update(Graphics g) {
                paint(g);
        }

        public Image ladeBild(String bild) {
                Image image=getImage(getDocumentBase(),bild);
                MediaTracker tracker=new MediaTracker(this);
                tracker.addImage(image,0);
                try {
                        tracker.waitForID(0);
                } catch (InterruptedException e) { }
                return image;
        }

        public void init() {
                setBackground(Color.white);
                Kugeln=new Image[8];
                for (int c=0;c<8;c++) Kugeln[c]=ladeBild("kugel"+c+".gif");
                Buffer=createImage(size().width,size().height);
                gBuffer=Buffer.getGraphics();
                gBuffer.setColor(getBackground());
                gBuffer.fillRect(0,0,size().width,size().height);
        }

        public void paint(Graphics g) {
                g.drawImage (Buffer,0,0, this);
                gBuffer.setColor(getBackground());
                gBuffer.fillRect(X,Y,Kugeln[KugelNr].getWidth(this),Kugeln[KugelNr].getHeight(this));
                X = 190 + (int) (170 * Math.sin (SinX));
                SinX += SinOffX;
                Y = 110 - (int) (Math.abs (110 * Math.sin (SinY)));
                SinY += SinOffY;
                WarteZähler--;
                if (WarteZähler<=0) {
                    KugelNr++;
                    if (KugelNr>=8) KugelNr=0;
                    WarteZähler=4;
                }
                gBuffer.drawImage(Kugeln[KugelNr],X, Y, this);
        }
}