Best Cat Applet

//  this applet displays an animation of a cat
//  double buffering is used to reduce flicker

import java.awt.Graphics;
import java.awt.Image;
import java.awt.Color;
import java.net.URL;

public class BestCat extends java.applet.Applet
                         implements Runnable {

    Image[] cats;
    Image currentImg;
    int xpos;
    int ypos;
    Thread runner;
    int grid;
    int imWidth;
    int imHeight;
    Image drawImg;
    Graphics offScreen;

    public void start() {
        if (runner == null) {
            runner = new Thread(this);
            runner.start();
        }
    }

    public void stop() {
        if (runner != null) {
            runner.stop();
            runner = null;
        }
    }

//  load the cat images and set the image position and grid size

    public void init()
    {
        URL baseLoc = getDocumentBase();
        String catnames[] = {"stop.gif", "yawn.gif","scratch1.gif","scratch2.gif",
                             "sleep1.gif","sleep2.gif","awake.gif"};
        cats = new Image[7];
        for (int i = 0 ; i < catnames.length ; i++)
            cats[i] = getImage(baseLoc,catnames[i]);
        xpos = 100;
        ypos = 100;
        grid = 10;
    }

//  draw the grid and then the current cat image

    public void paint(Graphics g)
    {
        int width = size().width/grid;
        int height = size().height/grid;
        boolean black = true;
        for (int y = 0 ; y <= grid ; y++)
            for (int x = 0 ; x <= grid ; x++)
            {
                if (black)
                {
                    g.setColor(Color.black);
                    black = false;
                }
                else
                {
                    g.setColor(Color.white);
                    black = true;
                }
                g.fillRect(x*width,y*height,width,height);
            }
        g.drawImage(currentImg,xpos,ypos,this);
    }

//  draw into image buffer drawImg and then copy to display
//  clip drawing area for efficiency

    public void update(Graphics g)
    {
        if (drawImg == null)
        {
            drawImg = createImage(size().width,size().height);
            offScreen = drawImg.getGraphics();
        }
        imWidth = currentImg.getWidth(this);
        imHeight = currentImg.getHeight(this);
        g.clipRect(xpos,ypos,imWidth,imHeight);
        paint(offScreen);
        g.drawImage(drawImg,0,0,this);
    }

//  cycle through the images so the cat scratches, sleeps, and wakes up

    public void run()
    {
        while (true)
        {
            currentImg = cats[0];
            repaint();
            pause(1000);
            currentImg = cats[1];
            repaint();
            pause(1000);
            scratch(4);
            sleep(5);
            currentImg = cats[6];
            repaint();
            pause(500);
        }
    }

    private void pause(int time)
    {
        try
        {
            Thread.sleep(time);
        }
        catch(InterruptedException e) {}
    }

//  sequence of images for scratching

    private void scratch(int times)
    {
        for (int i = 1 ; i <= times ; i++)
        {
            currentImg = cats[2];
            repaint();
            pause(150);
            currentImg = cats[3];
            repaint();
            pause(150);
        }
    }

//  sequence of images for sleeping

    private void sleep(int times)
    {
        for (int i = 1 ; i <= times ; i++)
        {
            currentImg = cats[4];
            repaint();
            pause(250);
            currentImg = cats[5];
            repaint();
            pause(250);
        }
    }

}