import java.awt.*;
import java.awt.geom.*;

/**
 * A Ball lives in a Box and can be moved and changed in various ways.
 */
public class Ball{

    private int centerX, centerY;
    private int radius = 20;
    private int stepX, stepY = 0;
    private Color color = Color.BLACK;
    private Box box;

/**
 * Create a black Ball with radius 20 and velocity zero 
 * and center at (x,y) in Box b.
 */
    public Ball(Box b,int x, int y){
        box = b;
        centerX = x;
        centerY = y;
        box.addBall(this);
        box.repaint();
    }
/** 
 * Move this Ball a one time unit step, i.e. change center position
 * with the current velocity.
 */
    public void step() {
        centerX = centerX + stepX;
        centerY = centerY + stepY;
        box.repaint();
    }


    public void setStepSizes(int dx, int dy){
        stepX = dx;
        stepY = dy;
    }

    public void setRadius(int r){
        radius=r;
        box.repaint();
    }

    public void setColor(Color col) {
        color = col;
        box.repaint();
    }

    public void paint(Graphics g){
        Graphics2D g2 = (Graphics2D)g;
        g2.setColor(color);
        g2.fill(new Ellipse2D.Double(centerX-radius,centerY-radius,2*radius,2*radius));
    }
}