/*  Scribble on a Canvas.
 * 
 * Functionality: The user can click on the canvas. Lines are drawn to connect the
 * points where the user clicks .
 * 
 * Note: all drawing done in the paint() method.
 * 
 * @author Laura Toma
 * 
 */

import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*;

public class Scribbler1 extends JFrame implements MouseInputListener {

    //store the crt and previous points where the user clicked on the
    //screen
    private Point prevPoint, crtPoint;
    
   
    public Scribbler1() {
        super("Scribble");
        setSize(400, 400);
	
	//exit on close 
	setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

	//the points are initially null 
	prevPoint = null; 
	crtPoint = null; 

        setVisible(true);
        
	addMouseMotionListener(this);
	addMouseListener(this);
    }
    
    public void paint(Graphics g) {
	//draw a line between last two points, if they exist
	if (prevPoint != null  && crtPoint != null) { 
	    g.drawLine((int)prevPoint.getX(), (int)prevPoint.getY(), 
		       (int)crtPoint.getX(), (int)crtPoint.getY());
	}
    }

    public void mousePressed(MouseEvent e) {
	//update last points
	prevPoint = crtPoint; 
	crtPoint = new Point(e.getX(), e.getY());
	
	//trigger repainting 
	repaint();
    }
    

    public void mouseDragged(MouseEvent e) {
	//update last two points
	prevPoint = crtPoint;
	crtPoint = new Point(e.getX(), e.getY());

	//trigger repainting 
	repaint();
    }
    
    
    public void mouseReleased(MouseEvent e) {
	//update last two points
	prevPoint = crtPoint = null;
    }

    public void mouseClicked(MouseEvent e) {}
   
    public void mouseEntered(MouseEvent e) {}
   
    public void mouseExited(MouseEvent e) {}
   
    public void mouseMoved(MouseEvent e) {}
   
    public static void main (String args[]) {
	Scribbler1 s = new Scribbler1();
    }
    
};