import java.applet.*;

import java.awt.*;

import java.awt.event.*;

import java.net.*;

import java.util.*;

/**

 * A Java applet that simulates a client-side imagemap.

 * Plays a sound whenever the user clicks on one of the hyperlinks.

 */

public class Soundmap extends Applet {

  protected Image image;      // The image to display.

  protected Vector rects;     // A list of rectangles in it.

  protected AudioClip sound;  // A sound to play on user clicks in a rectangle.

  /** Initialize the applet. */

  public void init() {

    // Look up the name of the image, relative to a base URL, and load it.

    // Note the use of three Applet methods in this one line.

    image = this.getImage(this.getDocumentBase(), this.getParameter("image"));

    // Lookup and parse a list of rectangular areas and the URLs they map to.

    // The convenience routine getRectangleParameter() is defined below.

    rects = new Vector();

    ImagemapRectangle r;

    for(int i = 0; (r = getRectangleParameter("rect" + i)) != null; i++)

      rects.addElement(r);

    // Look up a sound to play when the user clicks one of those areas.

    sound = this.getAudioClip(this.getDocumentBase(),

                  this.getParameter("sound"));

    // Specify an "event listener" object to respond to mouse button

    // presses and releases.  Note that this is the Java 1.1 event model.

    // Note that it also uses a Java 1.1 inner class, defined below.

    this.addMouseListener(new Listener());

  }

  /** Called when the applet is being unloaded from the system.

   * We use it here to "flush" the image we no longer need. This may

   * result in memory and other resources being freed more quickly. */

  public void destroy() { image.flush(); }

  /** To display the applet, we simply draw the image. */

  public void paint(Graphics g) { g.drawImage(image, 0, 0, this); }

  /** We override this method so that it doesn't clear the background

   * before calling paint().  No clear is necessary, since paint() overwrites

   * everything with an image.  Causes less flickering this way. */

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

  /** Parse a comma-separated list of rectangle coordinates and a URL.

   * Used to read the imagemap rectangle definitions from applet parameters. */

  protected ImagemapRectangle getRectangleParameter(String name) {

    int x, y, w, h;

    URL url;

    String value = this.getParameter(name);

    if (value == null) return null;

    try {

      StringTokenizer st = new StringTokenizer(value, ",");

      x = Integer.parseInt(st.nextToken());

      y = Integer.parseInt(st.nextToken());

      w = Integer.parseInt(st.nextToken());

      h = Integer.parseInt(st.nextToken());

      url = new URL(this.getDocumentBase(), st.nextToken());

    }

    catch (NoSuchElementException e) { return null; }

    catch (NumberFormatException e) { return null; }

    catch (MalformedURLException e) { return null; }

    return new ImagemapRectangle(x, y, w, h, url);

  }

  /**

   * An instance of this inner class is used to respond to mouse events.

   */

  class Listener extends MouseAdapter {

    /** The rectangle that the mouse was pressed in. */

    private ImagemapRectangle lastrect;

    /** Called when a mouse button is pressed. */

    public void mousePressed(MouseEvent e) {

      // On button down, check if we're inside one of the specified rectangles.

      // If so, highlight the rectangle, display a message, and play a sound.

      // The utility routine findrect() is defined below.

      ImagemapRectangle r = findrect(e);

      if (r == null) return;

      Graphics g = Applet.this.getGraphics();

      g.setXORMode(Color.red);

      g.drawRect(r.x, r.y, r.width, r.height);  // highlight rectangle

      Applet.this.showStatus("To: " + r.url);   // display URL

      sound.play();                             // play the sound

      lastrect = r;   // Remember the rectangle so it can be un-highlighted.

    }

    /** Called when a mouse button is released. */

    public void mouseReleased(MouseEvent e) {

      // When the button is released, un-highlight the rectangle.  If the

      // mouse is still inside it, ask the browser to go to the URL.

      if (lastrect != null) {

    Graphics g = Applet.this.getGraphics();

    g.setXORMode(Color.red);

    g.drawRect(lastrect.x, lastrect.y, lastrect.width, lastrect.height);

    Applet.this.showStatus("");   // Clear the message.

    ImagemapRectangle r = findrect(e);

    if ((r != null) && (r == lastrect))  // If still in the same rectangle

      Applet.this.getAppletContext().showDocument(r.url); // Go to the URL

    lastrect = null;

      }

    }

    /** Find the rectangle we're inside. */

    protected ImagemapRectangle findrect(MouseEvent e) {

      int i, x = e.getX(), y = e.getY();

      for(i = 0; i < rects.size(); i++)  {

    ImagemapRectangle r = (ImagemapRectangle) rects.elementAt(i);

    if (r.contains(x, y)) return r;

      }

      return null;

    }

  }

  /**

   * A helper class.  Just like java.awt.Rectangle, but with a URL field.

   * Note the use of a nested top-level class for neatness.

   */

  static class ImagemapRectangle extends Rectangle {

    URL url;

    public ImagemapRectangle(int x, int y, int w, int h, URL url) {

      super(x, y, w, h);

      this.url = url;

    }

  }

}