// This example is adapted from the book _Java in a Nutshell_ by David Flanagan.

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

public class Scribble extends Applet implements MouseListener, 
                                            MouseMotionListener,
                                            ActionListener {
    int last_x = 0;
    int last_y = 0;
    Color current_color = Color.black;
    Button clear_button = new Button("Clear");
    
    // This function is called initially, when the program begins
    // executing.  It initializes the applet and adds components to it.
    public void init() {
        // Set the background color
        this.setBackground(Color.white);

        // Add a clear button and a mouse listener to the applet
        add(clear_button);
        addMouseListener(this);   
		addMouseMotionListener(this);
		clear_button.addActionListener(this);
    }
    
    // Called when the user presses the mouse button to start a 
    // scribble.  Sets the values of variables last_x and last_y 
    // to mark the point of the click.
    public void mousePressed(MouseEvent e) {
       last_x = e.getX();
       last_y = e.getY();
    }
  
	// These four are unused by this program, but must be included
	// with MouseListener
    public void mouseReleased(MouseEvent e) { }
    public void mouseClicked(MouseEvent e) { }
    public void mouseExited(MouseEvent e) { }
    public void mouseEntered(MouseEvent e) { }
  
    // Called when the user scribbles with the mouse button down
    // Draws a line between the points (last_x, last_y) and (x, y)
    public void mouseDragged(MouseEvent e)
    {
        int x = e.getX();
        int y = e.getY();
        Graphics g = this.getGraphics();
        g.drawLine(last_x, last_y, x, y);
        last_x = x;
        last_y = y;
    }

    // This one is unused, but must be included with MouseMotionListener
    public void mouseMoved(MouseEvent e) {}

    // Called when the user clicks the Clear button, and 
    // clears the graphics window.
    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == clear_button) {
            Graphics g = this.getGraphics();
            Rectangle r = this.bounds();
            g.setColor(this.getBackground());
            g.fillRect(r.x, r.y, r.width, r.height);
        }
    }

}