package swingExamples;

import javax.swing.*;

import java.awt.*;

// a simple animation that moves a circle across the screen
// adapted from Head First Java, page 384

public class SimpleAnimation {

	private int x, y;	// circle's coordinates
	private JFrame frame;
	private PaintPanel paintPanel;
	
	private class PaintPanel extends JPanel
	{
		// called by the system when necessary to repaint( )
		public void paintComponent(Graphics g )
		{
			super.paintComponent(g);
			
			// clear the screen
			g.setColor(Color.white);
			g.fillRect(0, 0, this.getWidth(), this.getHeight());
			
			// draw the circle in its new position
			g.setColor(Color.blue);
			g.fillOval(x, y, 40, 40);
		}
	}
	
	public SimpleAnimation( )
	{
		frame = new JFrame("A Simple Animation");
		frame.setSize( 300, 300);
		frame.setLocation( 200, 200);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

		paintPanel = new PaintPanel();
		frame.add(BorderLayout.CENTER, paintPanel);
	}
	
	public void launch( )
	{
		frame.setVisible(true);
		for (int i = 0; i < 1; i++)
		{
			// change the circle's coordinates
			++x; ++y;
			// force the panel to repaint itself
			paintPanel.repaint();
			try {  // wait 50ms 
				Thread.sleep( 50 );
			}catch (Exception ex) {}			
		}
	}
	public static void main(String[] args) {
		SimpleAnimation animation = new SimpleAnimation();
		animation.launch();
	}

	
}