import java.awt.*;
import java.awt.event.*;

public class DoodlePad extends java.applet.Applet implements ActionListener { 
	DrawPad dp;
	public void init() {
		setLayout( new BorderLayout() );
		add( "Center", dp = new DrawPad() );
		Panel p = new Panel();
		Button clearButton = new Button("Clear");
		clearButton.addActionListener( this );
		p.add( clearButton );
		add( "South", p );
	}
	public void actionPerformed( ActionEvent e ) {
System.out.println("clear!");
		dp.clear();
	}
}

class DrawPad extends Canvas {
	Image drawImg;
	Graphics drawGr;
	int xpos, ypos, oxpos, oypos;

	DrawPad() {
		setBackground( Color.white );
		enableEvents( AWTEvent.MOUSE_EVENT_MASK 
			| AWTEvent.MOUSE_MOTION_EVENT_MASK );
	}

	public void processEvent( AWTEvent e ) {
		int x = ((MouseEvent)e).getX(), y = ((MouseEvent)e).getY();
		if ( e.getID() == MouseEvent.MOUSE_DRAGGED ) {
			xpos = x; ypos = y;
			if ( drawGr != null )
				drawGr.drawLine( oxpos, oypos, oxpos=xpos, oypos=ypos );
			repaint();
		} else 
		if ( e.getID() == MouseEvent.MOUSE_PRESSED ) {
			oxpos = x; oypos = y;
		}
		super.processEvent(e);
	}

	public void update( Graphics g ) {
		paint(g);
	}
	public void paint( Graphics g ) {
		if ( drawImg == null ) {
			drawImg = createImage( getSize().width, getSize().height );
			drawGr = drawImg.getGraphics();
		}
		g.drawImage(drawImg, 0, 0, null);
	}

	public void clear() {
		drawGr.clearRect(0, 0, getSize().width, getSize().height);
		repaint();
	}
}