/** 
 * Rebound.java 
 *
 * Demonstrates an animation and the use of the Timer class.
 * @author Lewis and Loftus.  Converted to JApplet by Scot Drysdale
 */

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class Rebound extends JApplet {
	private static final long serialVersionUID = 1L;
	private final int APPLET_WIDTH = 200;
	private final int APPLET_HEIGHT = 100;
	private final int IMAGE_SIZE = 35;
	private final int DELAY = 20;

	private Timer timer;             // Timer object to get regular callbacks
	private Image image;             // Image of thing to be drawn
	private int x, y, moveX, moveY;  // 

	/**
	 * Sets up the applet, including the timer for the animation.
	 */
	public void init() {
		addMouseListener(new ReboundMouseListener());

		Container cp = getContentPane();  // Content pane holds components
		cp.add(new Canvas());             // The canvas is the only component

		x = 0;
		y = 40;
		moveX = moveY = 3;

		image = getImage(getCodeBase(), "happyFace.gif");

		setBackground(Color.black);
		setSize(APPLET_WIDTH, APPLET_HEIGHT);

		timer = new Timer(DELAY, new ReboundActionListener());
		timer.start();

		setVisible(true);   // Makes the applet (and its components) visible
	}

	private class Canvas extends JPanel {
		private static final long serialVersionUID = 1L;

		/**
		 * Draws the image in the current location.
		 * @param page the graphics object to draw on.
		 */
		public void paintComponent(Graphics page) {
			super.paintComponent(page);
			page.drawImage(image, x, y, this);
		}
	}
	/**
	 * Represents the mouse listener for the applet.
	 */
	private class ReboundMouseListener implements MouseListener {
		/**
		 * Stops or starts the timer (and therefore the animation)
		 * when the mouse button is clicked.
		 * @param event the event that caused this callback
		 */
		public void mouseClicked(MouseEvent event) {
			if (timer.isRunning())
				timer.stop();
			else
				timer.start();
		}

		//--------------------------------------------------------------
		//  Provide empty definitions for unused event methods.
		//--------------------------------------------------------------
		public void mouseEntered(MouseEvent event) {}
		public void mouseExited(MouseEvent event) {}
		public void mousePressed(MouseEvent event) {}
		public void mouseReleased(MouseEvent event) {}
	}

	/**
	 * Represents the action listener for the timer.
	 */
	private class ReboundActionListener implements ActionListener {
		/**
		 * Updates the position of the image and possibly the direction
		 * of movement whenever the timer fires an action event.
		 * @param event the event that caused this callback
		 */
		public void actionPerformed(ActionEvent event) {
			x += moveX;
			y += moveY;

			if (x <= 0 || x >= APPLET_WIDTH - IMAGE_SIZE)
				moveX = moveX * -1;

			if (y <= 0 || y >= APPLET_HEIGHT - IMAGE_SIZE)
				moveY = moveY * -1;

			repaint();
		}
	}
}