package com.mkyong;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;


public class CircleClass extends JPanel {

    private static final long serialVersionUID = 3725359877575347978L;

    public static int x;

    public static int y;

    public static int w = 50;
    public static int h = 50;

    //public int delay = 10; //in miliseconds



    public void paintComponent(Graphics g) {

    super.paintComponent(g);
    //calculate the center of the circles
    x = getWidth()/2-w/2;
    y = getHeight()/2-h/2;


    g.setColor(Color.white);
    g.fillOval(x,y,w,h);

    //free the graphics context  again
    g.dispose();
    }




        public static void main (String [] arg){

        CircleClass circle  = new CircleClass();
        JFrame  frame = new JFrame();
        frame.getContentPane().setBackground(Color.black);
        frame.add(circle);
        circle.setOpaque(false);
        frame.setSize(400,400);
        frame.setVisible(true);



        while (true)
        {
        for (int i=0; i<150; i++){
            h++;
            w++;
            circle.repaint();
            try {
                Thread.sleep(15);
            }catch(Exception ex){}
            }

        for (int j=150; j>0; j--){
            h--;
            w--;
            circle.repaint();
            try {
                Thread.sleep(15);
            }catch(Exception ex){}
            }
        }






      }
}