/**
   程序功能：在框架上動態的畫出水波
*/
import javax.swing.*;
import java.awt.*;
import java.awt.geom.*;
import java.awt.event.*;
import javax.swing.Timer.*;
public class CircleTest
{
   public static void main(String[] args)
   {
      CircleFrame frame=new CircleFrame();
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.show();
   }
}

// 主框架類
class CircleFrame extends JFrame
{
   public CircleFrame()
   {
      setTitle("ButtonFrame");
      setSize(DEFAULT_WIDTH,DEFAULT_HEIGHT);
      Container content=getContentPane();
      CirclePanel panel=new CirclePanel();
      content.add(panel);
   }
   public static final int DEFAULT_WIDTH=400;
   public static final int DEFAULT_HEIGHT=400;
}

//主畫板類
class CirclePanel extends JPanel
{
	public CirclePanel()
	{
        JButton closeButton=new JButton("quite");
        add(closeButton);
        closeButton.addActionListener(new ActionListener()
        {
			public void actionPerformed(ActionEvent event)
			{
	            System.exit(0);
			}
		}
        );

    }
    public void paintComponent(Graphics g)
    {
	    //Timer計時器
	    ActionListener listener=new ActionPerformed();
	    Timer t=new Timer(1000,listener);
	    t.start();
	}

	//內部類實現Timer計時器接口，動態畫出水波
	private class ActionPerformed implements ActionListener
	{
		int topx=175;
		int topy=175;
		int r=50;
		public void actionPerformed(ActionEvent event)
		{
			Graphics g=getGraphics();                                       //用getGraphics()方法獲得g對象
			Graphics2D g2=(Graphics2D)g;

			//畫水波
			Ellipse2D circle=new Ellipse2D.Double(topx,topy,r,r);
			g2.draw(circle);
			topx=topx-10;
			topy=topy-10;
			r=r+20;
		}
	}

}