import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.MediaTracker;
import java.awt.Point;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.Timer;


/** A demonstration of simple animation in a JPanel.
  * Uses Java Timer objects to do a delayed repainting of a panel
  * to create an animation effect.  Requires file spot.gif in the
  * same folder.
  *
  * <p>
  * Note that there are two kinds of animation going on here:
  * 1) The "dancing" of Spot himself (which is not because of my
  *    code, but rather because the spot.gif file is an animated 
  *    GIF image that I downloaded off the web)
  * 2) Spot moving across the screen, which IS because of my code.
  *
  * @author Martin Stepp
  * @version Thursday, November 9, 2000
  */
public class AnimationDemo extends JFrame implements ActionListener {
	private JButton goButton = null;
	private AnimationPanel animatedPane = null;
	
	/** Runs the program. */
	public static void main(String[] args) {
		AnimationDemo demo = new AnimationDemo();
		demo.show();
	}
	
	
	/** Constructs a new animation frame, sets up events, and does layout. */
	public AnimationDemo() {
		super("CS335 Marty's Animation Demo");
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		
		animatedPane = new AnimationPanel("spot.gif");
		goButton = new JButton("Go");
		goButton.addActionListener(this);
		JLabel infoLabel = new JLabel("Set the two endpoints, then click the button!");
		
		// layout
		JPanel contentPane = new JPanel(new BorderLayout());
		contentPane.add(goButton, BorderLayout.NORTH);
		contentPane.add(animatedPane, BorderLayout.CENTER);
		contentPane.add(infoLabel, BorderLayout.SOUTH);
		setContentPane(contentPane);
		
		pack();  // resize frame so its size is "just right"
		show();
	}
	
	
	public void actionPerformed(ActionEvent event) {
		animatedPane.animate();

		if (goButton.getText().equals("Go"))
			goButton.setText("Reset");
		else
			goButton.setText("Go");
	}
}



/** A JPanel that draws an animated picture when so instructed. */
class AnimationPanel extends JPanel {
	private static final int NUM_MILLISECONDS = 10;
	
	private Point   myStartPoint, myEndPoint;
	private int     myPercentage;
	private boolean myToggle;
	private boolean myIsAnimated;
	private Image   myImage;
	private int     myImageWidth, myImageHeight;
	private Timer   myTimer;

	/** Constructs a new AnimationPanel for the image with the given file name.
	  *
	  * @param fileName the file name of the image to load.
	  */
	public AnimationPanel(String fileName) {
		Dimension size = new Dimension(myImageWidth + 400, myImageHeight + 200);
		setPreferredSize(size);
		setBackground(Color.white);
		
		myStartPoint = new Point(0, 0);
		myEndPoint   = new Point(size.width - 50, size.height - 50);
		myPercentage = 0;
		myToggle     = false;
		myIsAnimated = false;
		
		// set up the image to animate (in this case, the 7-Up Spot)
		myImage = Toolkit.getDefaultToolkit().getImage(fileName);
		MediaTracker mt = new MediaTracker(this);
		mt.addImage(myImage, 0);
		try {
			mt.waitForAll();
		} catch (InterruptedException ie) {
			System.out.println("Error while loading image: " + ie);
		}
		
		myImageWidth  = myImage.getWidth(this);
		myImageHeight = myImage.getHeight(this);
		
		// set up a Timer to repaint every 10 milliseconds.
		//
		// When passed an int number of milliseconds and an ActionListener,
		// the Timer fires ActionEvents at the given intervals
		// (in this case, every 10 ms) from the time .start() is
		// called until the time .stop() is called.
		//
		ActionListener updater = new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				myPercentage++;
				if (myPercentage >= 100)
					myTimer.stop();
				repaint();
			}
		};
		myTimer = new Timer(NUM_MILLISECONDS, updater);
		
		// set up a MouseListener to change the start and end points
		MouseListener clicker = new MouseAdapter() {
			/** Stops animation and resets either start or end point. */
			public void mousePressed(MouseEvent event) {
				if (myToggle)
					myStartPoint = event.getPoint();
				else
					myEndPoint = event.getPoint();

				myToggle = !myToggle;
				myIsAnimated = false;
				myTimer.stop();
				myPercentage = 0;
				repaint();
			}
		};
		addMouseListener(clicker);
	}


	/** Paints this AnimationPanel on the screen.
	  *
	  * @param g the graphical context of the panel.
	  */
	public void paintComponent(Graphics g) {
		super.paintComponent(g);
		
		// get difference between start and end points to see how
		// far I need to move Spot
		int xDiff = myEndPoint.x - myStartPoint.x;
		int yDiff = myEndPoint.y - myStartPoint.y;
		
		// draw Spot!
		g.drawImage(myImage,
			myStartPoint.x + xDiff * myPercentage / 100,
			myStartPoint.y + yDiff * myPercentage / 100,
			this
		);

		// draw Start and End Strings at start and end points (offset a bit)
		g.drawString("Start",
			myStartPoint.x + myImageWidth / 2,
			myStartPoint.y + myImageWidth / 2
		);
		g.drawString("End",
			myEndPoint.x + myImageWidth / 2,
			myEndPoint.y + myImageWidth / 2
		);
		
		if (myIsAnimated  &&  myPercentage < 100) {
			// draw "look at him go" in center of panel
			String message = "Look at him go!";
			Dimension size = getSize();
			Font font = getFont();
			FontMetrics fm = getFontMetrics(font);
			int x = (size.width - fm.stringWidth(message)) / 2;
			int y = (size.height - font.getSize()) / 2;;
			
			g.drawString(message, x, y);
		}
	}


	/** Instructs this AnimationPanel to restart its animation sequence. */
	public void animate() {
		myPercentage = 0;
		myIsAnimated = !myIsAnimated;
		
		if (myIsAnimated)
			myTimer.start();
		else
			myTimer.stop();
	}
}