import javabook.*;
import java.awt.*;

/**
 * DrawingLab3
 * Inspired by a lab from Jeff Ondich
 * @author Dave Musicant
 * @version 2.0 12/20/01
 *
 * 0. Compile it, run it, and figure out how it works.
 *
 * 1. Complain about the flickering.
 *
 * 2. To slow the motion down or speed it up, change the argument
 *    to Thread.sleep() (measured in milliseconds).
 *
 * 3. Try to get the box to bounce from side to side instead of up
 *    and down.
 *
 * 4. Modify your program so that your box doesn't go behind the borders
 *    or the titlebar.
 *
 * 5. Can you get the colors to change gradually from red to blue
 *    instead of abruptly? Remember, you can define colors with
 *    the right arguments to "new Color()".
 */

class DrawingLab3 extends MainWindow
{
    // Data values
    final private int windowWidth = 600;
    final private int windowHeight = 600;

    private int positionX;
    private int positionY;
    private int squareSize;
    private Color squareColor;
    private Color currentColor;
    private Color backgroundColor;
    private boolean goingUp;

    public DrawingLab3()
    {
	setVisible(true);
	toFront();

	setSize(windowWidth,windowHeight);
	backgroundColor = Color.white;
	setBackground(backgroundColor);

	squareSize = 50;
	positionX = windowWidth / 2;
	positionY = windowHeight / 2;
	goingUp = true;
	squareColor = Color.blue;
    }

    public void paint(Graphics graphics)
    {
	graphics.setColor(currentColor);
	graphics.drawRect(positionX,positionY,squareSize,squareSize);
    }

    public void animate()
    {
	// Do the animation. This is an intentionally infinite loop.

	while(true)
	{
	    // Draw the square
	    currentColor = squareColor;
	    repaint();

	    // Wait a while. If Thread.sleep throws an EXCEPTION,
	    // catch the exception and ignore it.
	    try 
	    {
		Thread.sleep(10);
	    }
	    catch (InterruptedException e)
	    {
	    }

	    // Erase the square
	    currentColor = backgroundColor;
	    repaint();

	    // Move the square
	    newCenter();

	}
    }
     
    private void newCenter()
    {
	if (goingUp)
	    positionY = positionY - 1;
	else
	    positionY = positionY + 1;

	if (positionY >= windowHeight - squareSize)
	{
	    goingUp = true;
	    squareColor = Color.blue;
	}
	else if (positionY <= 0)
	{
	    goingUp = false;
	    squareColor = Color.red;
	}
    }

    public static void main(String[] args)
    {
	DrawingLab3 dw = new DrawingLab3();
	dw.animate();
    }

}