/* * Copyright (c) 2000 David Flanagan.  All rights reserved. * This code is from the book Java Examples in a Nutshell, 2nd Edition. * It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied. * You may study, use, and modify it for any non-commercial purpose. * You may distribute it non-commercially as long as you retain this notice. * For a commercial use license, or to purchase the book (recommended), * visit http://www.davidflanagan.com/javaexamples2. */package com.davidflanagan.examples.applet;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 implements MouseListener {    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    protected ImagemapRectangle highlight; // Which rectangle is highlighted    /** 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 their URLs.        // 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.        this.addMouseListener(this);    }    /**     * 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, and highlight the     * current rectangle if any.     **/    public void paint(Graphics g) {	g.drawImage(image, 0, 0, this);	if (highlight != null) {	    g.setColor(Color.red);	    g.drawRect(highlight.x, highlight.y,		       highlight.width, highlight.height);	    g.drawRect(highlight.x+1, highlight.y+1,		       highlight.width-2, highlight.height-2);	}    }    /**     * 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);    }    /** Called when a mouse button is pressed. */    public void mousePressed(MouseEvent e) {	// On button down, check if we're inside one of the 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 a rectangle is found, and is not already highlighted	if (r != null && r != highlight) {	    highlight = r;                // Remember which rectangle it is	    showStatus("To: " + r.url);   // display its URL in status line	    sound.play();                 // play the sound	    repaint();                    // request a redraw to highlight it	}    }    /** Called when a mouse button is released. */    public void mouseReleased(MouseEvent e) {	// If the user releases the mouse button over a highlighted	// rectangle, tell the browser to display its URL.  Also,	// erase the highlight and clear status	if (highlight != null) {	    ImagemapRectangle r = findrect(e);	    if (r == highlight)  getAppletContext().showDocument(r.url);	    showStatus("");     // clear the message.	    highlight = null;   // forget the highlight	    repaint();          // request a redraw	}    }    /** Unused methods of the MouseListener interface */    public void mouseEntered(MouseEvent e) {}    public void mouseExited(MouseEvent e) {}    public void mouseClicked(MouseEvent e) {}    /** 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 toplevel 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;        }    }}