import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import java.awt.Color;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;
import java.awt.Image;
import java.awt.Rectangle;
import java.awt.image.BufferedImage;
import java.awt.image.ImageObserver;
 
public class SimplePaintWithBuffer extends JPanel implements ImageObserver {
	private boolean painting = false;
	private int currentX, currentY;
	private BufferedImage image;
	private Graphics2D graphics;
	
 	public static final int WINDOW_WIDTH = 640;
	public static final int WINDOW_HEIGHT = 480;
	
	public static void main(final String[] args) {
       		JFrame frame = new JFrame("Smile!");
 	      	frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
       		frame.setSize(WINDOW_WIDTH, WINDOW_HEIGHT);
      	 	frame.setLocationRelativeTo(null);
       		
		SimplePaintWithBuffer paint = new SimplePaintWithBuffer();
		frame.setContentPane(paint);
		paint.init();
		
		// Important: put this after everything else.
		frame.setVisible(true);
	}
    
	public SimplePaintWithBuffer() {
	}

	public void init() {
		image = new BufferedImage(WINDOW_WIDTH, WINDOW_HEIGHT, BufferedImage.TYPE_INT_RGB);
		graphics = image.createGraphics();
		addMouseListener(new MouseAdapter() {
			public void mousePressed(MouseEvent e) {
				painting = true;
				currentX = e.getX();
				currentY = e.getY();
				writeImage();
				repaint();
			}

			public void mouseReleased(MouseEvent e) {
				painting = false;
			}
		});
			
		addMouseMotionListener(new MouseMotionAdapter() {
			public void mouseDragged(MouseEvent e) {
				currentX = e.getX();
				currentY = e.getY();
				writeImage();
				repaint();
			}
		});
	}	

	public void writeImage() {
		graphics.setColor(Color.green);
		graphics.fillOval(currentX - 4, currentY - 4, 8, 8);
			
		String coords = "X: " + currentX + " Y: " + currentY;
			
		FontMetrics metrics = graphics.getFontMetrics();
		Rectangle rect = metrics.getStringBounds(coords, graphics).getBounds();
			
		graphics.setColor(getBackground());
		graphics.fillRect(10, WINDOW_HEIGHT - 50 - rect.height, rect.width + 20, rect.height);
		graphics.setColor(Color.black);
		graphics.drawString(coords, 10, WINDOW_HEIGHT - 50);
	}

	public boolean imageUpdate(Image img, int infoflags, int x, int y, int width, int height) {
		return false;
	}

	public void paint(Graphics g) {
		Graphics2D g2d = (Graphics2D)g;

		g2d.drawImage(image, 0, 0, Color.white, this); 
	}
		
}