/**
 * This applet displays an animation.  It doesn't handle errors while
 * loading images. It doesn't wait for all images to be loaded before
 * starting the animation. This stuff will be addressed elsewhere.
 **/

import java.applet.*;
import java.awt.*;
import java.net.*;
import java.util.*;

public class Animator extends Applet implements Runnable {
  protected Image[] images;
  protected int current_image;
  protected int sleep;

  // REad the basename and num_images parameters
  // The read in the images, using the specified base name.
  // For example, if basename is images/anim, read images/anim0,
  // images/anim1, etc.  These are relative to the current document URL.
  public void init() {
    String basename = this.getParameter("basename");
    int num_images;
    try { num_images = Integer.parseInt(this.getParameter("num_images")); }
    catch (NumberFormatException e) { num_images = 0; }

    images = new Image[num_images];
    for (int i = 0; i<num_images; i++) {
      images[i] = this.getImage(this.getDocumentBase(),basename+i);
    }

    sleep = 200;
    try { sleep = Integer.parseInt(this.getParameter("delay")); }
    catch (NumberFormatException e) { sleep = 200; }

  }

  // This is the thread that runs the animation, and the methods
  // that start it and stop it.
  private Thread animator_thread = null;

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

  public void stop() {
    if ( (animator_thread != null) && animator_thread.isAlive() )
      animator_thread.stop();
    // We do this so the garbage collector can reclaim the Thread object.
    // Otherwise it might sit around in the Web browser for a long time.
    animator_thread = null;
  }

  // This is the body of the thread - the method that does the animation
  public void run() {
    while(true) {
      if (++current_image >= images.length) current_image = 0;
      this.getGraphics().drawImage(images[current_image],0,0,this);
      showStatus("frame: " + current_image);
      try {Thread.sleep(sleep);} catch (InterruptedException e);
    }
  }
}