// ImageMap.java (V7.0)
//
// Written by Chris Carter, 2nd October 1998
// Changes an image when the mouse enters or exits its area. Uses a different, simpler method to
// change the image. Overrides the 'update' method to eliminate flicker. Also uses a media tracker
// to check when images are loaded, and will go to a URL when clicked!
// JDK 1.1.6

import java.awt.*;			// Graphics
import java.util.*;			// General stuff
import java.net.*;			// Networking
import java.awt.event.*;	// Event handlers
import java.lang.*;			// Parses Strings to other things

public class ImageMap extends java.applet.Applet implements MouseListener {

Image untouchedImage, touchedImage, drawnImage;	// Declare instances of Image
MediaTracker tracker;							// MediaTracker monitors the load-progress of the images

String imageBaseLocation, defaultImage, alternateImage, destinationURL, showURL, changeCursor, debug;

boolean ENABLE_DEBUG, ENABLE_SHOW_URL, ENABLE_CHANGE_CURSOR;

boolean ENTERED = false;	// ENTERED is false unless the mouse is over the applet area

URL loadThisURL;	// URL to load when the applet is clicked
URL defaultImageURL, alternateImageURL;

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

public void init() {

// Get the applet parameters that the user has defined

	imageBaseLocation = getParameter("imageBaseLocation");

	defaultImage = getParameter("defaultImage");
	alternateImage = getParameter("alternateImage");
	defaultImageURL = makeURL(defaultImage);
	alternateImageURL = makeURL(alternateImage);
	
	destinationURL = getParameter("destinationURL");
	loadThisURL = makeURL(destinationURL);
		
	showURL = getParameter("showURL");
	ENABLE_SHOW_URL = (Boolean.valueOf(showURL)).booleanValue();
	
	changeCursor = getParameter("changeCursor");
	ENABLE_CHANGE_CURSOR = (Boolean.valueOf(changeCursor)).booleanValue();

	debug = getParameter("debug");
	ENABLE_DEBUG = (Boolean.valueOf(debug)).booleanValue();
	
	tracker = new MediaTracker(this);							// Add a MediaTracker to this applet

    untouchedImage = getImage(defaultImageURL);		// Get the 'default' imagemap image
	touchedImage = getImage(alternateImageURL);		// Get the 'moused' imagemap image
	
	tracker.addImage(untouchedImage, 0);			// Add the default image to the tracker, highest priority
	tracker.addImage(touchedImage, 1);		// Add the 'moused' image to the tracker, lower priority
	
	try {
		tracker.waitForAll();				// Try downloading the images & wait until they are all in
		}
		catch (InterruptedException e) {}

//	while (!tracker.checkAll()) {
//		showStatus("Loading images...");
//		}
	
	drawnImage = untouchedImage;					// The first image to draw is the 'default' - untouchedImage
	
	this.addMouseListener(this);			// Add a MouseListener to this applet

// Allows the cursor to change to the 'hand' style when over the applet
	
	if (ENABLE_CHANGE_CURSOR) {
		this.setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));
		}

	if (ENABLE_DEBUG) {
		System.out.println("Init: ");
		System.out.println("getCodeBase: " + getCodeBase());
		}

}

public void mouseClicked(MouseEvent e) {
	getAppletContext().showDocument(this.loadThisURL);
}
	
public void mouseEntered(MouseEvent e) {
if (!ENTERED) {
	ENTERED = true;
	drawnImage = touchedImage;
	if (ENABLE_SHOW_URL) {
		showStatus(destinationURL);
		}
	repaint();
	}
	
if (ENABLE_DEBUG) {
	System.out.println("Entered applet area!");
	}
}

public void mouseExited(MouseEvent e) {
if (ENTERED) {
	ENTERED = false;
	drawnImage = untouchedImage;
	showStatus("");
	repaint();
	}
	
if (ENABLE_DEBUG) {
	System.out.println("Exited applet area!");
	}
}

public void mousePressed(MouseEvent e) {
}

public void mouseReleased(MouseEvent e) {
}

public void update(Graphics g) {
	if (tracker.checkAll() == false) {
		showStatus("Loading images...");
		}
	g.drawImage(drawnImage, 0, 0, this);
	}
	
public void paint(Graphics g) {
	update(g);
	}

// Called when the applet is destroyed. Ensures all AWT components are removed.

public void destroy() {
if (ENABLE_DEBUG) {
	System.out.println("Applet ImageMap destroyed.");
	}

	this.removeAll();
	}

// Implementing this method is recommended, it provides info about the applet.

public String getAppletInfo() {
	return "ImageMap applet by Chris Carter (chris.carter@iee.org)";
	}

public URL makeURL(String URL_string) {

// Turns a String description of a URL into a proper URL object

URL URLobject;
URLobject = null;

try {
	URLobject = new URL(URL_string);
	}
	catch (MalformedURLException e) {
		System.out.println("The URL " + URL_string + " is malformed!");
	}
	return URLobject;
	}
}