/* * Copyright (c) 2000 David Flanagan.  All rights reserved. * This code is from the book Java Examples in a Nutshell, 2nd Edition. * It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied. * You may study, use, and modify it for any non-commercial purpose. * You may distribute it non-commercially as long as you retain this notice. * For a commercial use license, or to purchase the book (recommended), * visit http://www.davidflanagan.com/javaexamples2. */package com.davidflanagan.examples.gui;import javax.swing.*;       // For JPanel componentimport java.awt.*;          // For Graphics objectimport java.awt.event.*;    // For Event and Listener objects/** * A simple JPanel subclass that uses event listeners to allow the user * to scribble with the mouse.  Note that scribbles are not saved or redrawn. **/public class ScribblePane2 extends JPanel {    public ScribblePane2() {	// Give the component a preferred size	setPreferredSize(new Dimension(450,200));	// Register a mouse event handler defined as an inner class	// Note the call to requestFocus().  This is required in order for	// the component to receive key events.	addMouseListener(new MouseAdapter() {		public void mousePressed(MouseEvent e) { 		    moveto(e.getX(), e.getY());  // Move to click position		    requestFocus();              // Take keyboard focus		}	    });	// Register a mouse motion event handler defined as an inner class	// By subclassing MouseMotionAdapter rather than implementing	// MouseMotionListener, we only override the method we're interested	// in and inherit default (empty) implementations of the other methods.	addMouseMotionListener(new MouseMotionAdapter() {		public void mouseDragged(MouseEvent e) {		    lineto(e.getX(), e.getY());  // Draw to mouse position		}	    });	// Add a keyboard event handler to clear the screen on key 'C'	addKeyListener(new KeyAdapter() {		public void keyPressed(KeyEvent e) {		    if (e.getKeyCode() == KeyEvent.VK_C) clear();		}	    });    }        /** These are the coordinates of the the previous mouse position */    protected int last_x, last_y;    /** Remember the specified point */    public void moveto(int x, int y) {	last_x = x;	last_y = y;    }    /** Draw from the last point to this point, then remember new point */    public void lineto(int x, int y) {	Graphics g = getGraphics();          // Get the object to draw with	g.setColor(color);                   // Tell it what color to use	g.drawLine(last_x, last_y, x, y);    // Tell it what to draw	moveto(x, y);                        // Save the current point    }    /**     * Clear the drawing area, using the component background color.  This     * method works by requesting that the component be redrawn.  Since this     * component does not have a paintComponent() method, nothing will be     * drawn.  However, other parts of the component, such as borders or     * sub-components will be drawn correctly.     **/    public void clear() { repaint(); }    /** This field holds the current drawing color property */    Color color = Color.black;     /** This is the property "setter" method for the color property */    public void setColor(Color color) { this.color = color; }    /** This is the property "getter" method for the color property */    public Color getColor() { return color; }}