// graphics/Sprite.java
import java.applet.*; 
import java.awt.*; 
import java.awt.event.*; 
import java.util.*; 
 
/** A Sprite is one Image that moves around the screen on its own */ 
class Sprite extends Component implements Runnable { 
    protected static int spriteNumber = 0; 
    protected Thread t; 
    protected int x, y; 
    protected Bounce parent; 
    protected Image img; 
    protected boolean done = false; 
 
    /** Construct a Sprite with a Bounce parent: construct 
     * and start a Thread to drive this Sprite. 
     */ 
    Sprite(Bounce parent, Image img) { 
        super(  ); 
        this.parent = parent; 
        this.img = img; 
        setSize(img.getWidth(this), img.getHeight(this)); 
        t = new Thread(this); 
        t.setName("Sprite #" + ++spriteNumber); 
        t.start(  ); 
    } 
 
    /** Stop this Sprite's thread. */ 
    void stop(  ) { 
        System.out.println("Stopping " + t.getName(  )); 
        done = true; 
    } 
 
    /** 
     * Run one Sprite around the screen. 
     * This version is very stupid, and just moves them around 
     * at some 45-degree angle. 
     */ 
    public void run(  ) { 
        int width = parent.getSize(  ).width; 
        int height = parent.getSize(  ).height; 
        // Random location 
        x = (int)(Math.random(  ) * width); 
        y = (int)(Math.random(  ) * height); 
        // Flip coin for x & y directions 
        int xincr = Math.random(  )>0.5?1:-1; 
        int yincr = Math.random(  )>0.5?1:-1; 
        while (!done) { 
            width = parent.getSize(  ).width; 
            height = parent.getSize(  ).height; 
            if ((x+=xincr) >= width) 
                x=0; 
            if ((y+=yincr) >= height) 
                y=0; 
            if (x<0) 
                x = width; 
            if (y<0) 
                y = height; 
            // System.out.println("Move " + t.getName(  ) + " from " + 
            //     getLocation(  ) + " to " + x + "," + y); 
            setLocation(x, y); 
            repaint(  ); 
            try { 
                Thread.sleep(250); 
            } catch (InterruptedException e) { 
                return; 
            } 
        } 
        } 
 
    /** paint -- just draw our image at its current location */ 
    public void paint(Graphics g) { 
        g.drawImage(img, 0, 0, this); 
    } 
} 
 
// graphics/Bounce.java
/** This is the main class; create and start Sprites. */ 
public class Bounce extends Applet implements ActionListener { 
    Panel p; 
    Image img; 
    Vector v; 
 
    public void init(  ) { 
        Button b = new Button("Start"); 
        b.addActionListener(this); 
        setLayout(new BorderLayout(  )); 
        add("North", b); 
        add("Center", p = new Panel(  )); 
        p.setLayout(null); 
        String imgName = getParameter("imagefile"); 
        if (imgName == null) imgName = "duke.gif"; 
        img = getImage(getCodeBase(  ), imgName); 
        MediaTracker mt = new MediaTracker(this); 
        mt.addImage(img, 0); 
        try { 
            mt.waitForID(0); 
        } catch(InterruptedException e) { 
            throw new IllegalArgumentException( 
                "InterruptedException while loading image " + imgName); 
        } 
        if (mt.isErrorID(0)) { 
            throw new IllegalArgumentException( 
                "Couldn't load image " + imgName); 
        } 
        v = new Vector(  ); 
    } 
 
    public void actionPerformed(ActionEvent e) { 
        System.out.println("Creat-ing another one!"); 
        Sprite s = new Sprite(this, img); 
        p.add(s); 
        v.addElement(s); 
    } 
 
    public void stop(  ) { 
        for (int i=0; i<v.size(  ); i++) { 
            ((Sprite)(v.get(i))).stop(  ); 
        } 
        v.clear(  ); 
    } 
}