Load Fast images in Applet using MediaTracker

The demonstration applet loads three images, called anim1.gif, anim2.gif, anim3.gif, from the base directory of the page from which the applet is loaded. If you'd like to modify the applet, you could increase the number of images, change the name or location, or change the speed of animation.

package org.best.example;

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

//
//
// MediaTrackerDemo
//
//
public class MediaTrackerDemo extends Applet implements Runnable
{
    Image[]      imgArray = null;
    MediaTracker tracker  = null;
    int    current  = 0;
    Thread   animThread=null;

    // Check for a mouse click, to start the images downloading
    public boolean mouseDown(Event  evt, int  x, int  y)
    {
        if (tracker == null)
        {
            // Create a new media tracker, to track loading images
            tracker = new MediaTracker(this);

            // Create an array of three images
            imgArray = new Image[3];

            // Start downloading the images
            for (int index=0; index < 3; index++)
            {
                // Load the image
                imgArray[index] = getImage( getDocumentBase(),
                     "anim" + (index+1) + ".gif"); 

                // Register it with media tracker
                tracker.addImage(imgArray[index], index);
            }

            // Start animation thread
            animThread = new Thread(this);
            animThread.start();
        }

        return true;
    }

    public void update(Graphics g) {
        // Don't repaint gray background
        paint(g);
    }

    public void paint (Graphics g)
    {
        g.setColor(Color.white);
        g.fillRect(0,0, 200, 200);
        g.setColor(Color.black);

        // Check to see if images have started loading
        if (tracker == null)
        {
            g.drawString ("Click to start loading",20,20);
        }
        else
        // Check to see if images have loaded
        if (tracker.checkAll())
        {
            g.drawImage(imgArray[current++], 0, 0, this);

            if (current >= imgArray.length) current=0;
        }
        else
        // Still loading
        {
            g.drawString ("Images are loading...", 20,20);
        }
    }

    public void run()
    {
        try
        {
            tracker.waitForAll();

            for (;;)
            {
                // Repaint the images
                repaint();

                Thread.sleep(2000);
            }        
        }
        catch (InterruptedException ie) {};
    }
}