//
//	general purpose reusable bouncing ball abstraction
//	Described in Chapter 4 of
//	Understanding Object-Oriented Programming with Java
//	by Timothy A Budd
//	Published by Addison-Wesley
//
//	see ftp://ftp.cs.orst.edu/pub/budd/java/ReadMe.html
//	for further information
//

import java.awt.*;

/**
 * general class for Balls
 *
 * @version 1.0
 * @author Timothy Budd
 *
 */

public class Ball {

  /** surrounding rectangle for the Ball */
  protected Rectangle location;

  /** the initial delta along the x axis */
  protected double dx;

  /** the initial delta along the y axis */
  protected double dy;

  /** the color of the ball */
  protected Color color;
	

  /**
   *  Constructor to init both position and size
   * 
   *  <br> color is hard-coded to Color.blue
   *
   *  @param x the initial x coordinate of the center 
   *  @param y the initial y coordinate of the center 
   *  @param r the radius of the cannonball
   */
    public Ball (int x, int y, int r)
    {
	location = new Rectangle(x-r, y-r, 2*r, 2*r);
	dx = 0;
	dy = 0;
	color = Color.blue;
    }
	
    // functions that set attributes
    public void setColor (Color newColor)
    { color = newColor;	}

    public void setMotion (double ndx, double ndy)
    { dx = ndx; dy = ndy; }
	
    // functions that access attributes of ball

  /** 
   * recompute the radius of the ball from the surrounding rectangle
   *
   * @return the radius 
   */
    public int radius ()
    { return location.width / 2; }
	
    public int x ()
    { return location.x + radius(); }
	
    public int y ()
    { return location.y + radius(); }
	
    public double xMotion ()
    { return dx; }

    public double yMotion ()
    { return dy; }

    public Rectangle region () { return location; }

    // functions that change attributes of ball
    public void moveTo (int x, int y)
    { location.setLocation(x, y); }

  /** 
   * move the ball by the current @see dx and @see dy values
   */
    public void move ()
    { location.translate ((int) dx, (int) dy); }
	
    public void paint (Graphics g)
    {
	g.setColor (color);
	g.fillOval (location.x, location.y, location.width, location.height);
    }
}