/**
  * Copyright (c): Uwe Schmidt, FH Wedel
  *
  * You may study, modify and distribute this source code
  * FOR NON-COMMERCIAL PURPOSES ONLY.
  * This copyright message has to remain unchanged.
  *
  * Note that this document is provided 'as is',
  * WITHOUT WARRANTY of any kind either expressed or implied.
  */

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

//--------------------

public
class ImageAnimation
  extends Applet
  implements Runnable
{

  //--------------------

  Image [] images;
  int currImage = 0;
  int direction = +1;
  int delay = 500;

  //--------------------

  public
  void init() {

    // applet Parameter einlesen

    int noOfImages = Integer.parseInt(getParameter("noOfImages"));
    URL documentBase = getDocumentBase();
    String imageName = getParameter("image");

    try {
      delay = Integer.parseInt(getParameter("delay"));
    }
    catch (Exception e) { }


    // Bilder laden
    showStatus(noOfImages + " to load");

    images = new Image[noOfImages];
    for (int i = 0;
	 i < noOfImages;
	 ++i) {
      String n = imageName + i + ".gif";

      showStatus("loading image " + imageName);
      images[i] = getImage(documentBase,n);
    }
  }

  //--------------------

  public
  void destroy() {

    // Bilder wegwerfen
    for (int i = 0;
	 i < images.length;
	 ++i) {
      images[i].flush();
    }
  }

  //--------------------

  public
  void paint(Graphics g) {
    showStatus("drawing image " + currImage);
    g.drawImage(images[currImage],0,0,this);
  }

  public
  void update(Graphics g) {
    paint(g);
  }

  //--------------------
  // der animator thread

  Thread animatorThread;

  public
  void start() {

    // animator thread erzeugen
    // und starten
    if ( animatorThread == null ) {
      animatorThread = new Thread(this);
    }
    animatorThread.start();
  }

  //--------------------

  public
  void stop() {
    // animator thread vernichten
    animatorThread = null;
  }

  //--------------------
  // das run interface

  public
  void run() {

    while (Thread.currentThread() == animatorThread) {
      currImage += direction;
      if (currImage == images.length || currImage == -1) {
	direction = -direction;
	currImage += 2 * direction;
      }

      repaint();
      sleepAWhile();
    }
  }

  //--------------------
  // eine zeitlang nichts tun

  protected
  void sleepAWhile() {
    try {
      animatorThread.sleep(delay);
    }
    catch (InterruptedException e) {
    }
  }
}

//--------------------