import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import javax.swing.*;
/**
 * Description:
 * <br/>Copyright (C), 2005-2008, Yeeku.H.Lee
 * <br/>This program is protected by copyright laws.
 * <br/>Program Name:
 * <br/>Date:
 * @author  Yeeku.H.Lee kongyeeku@163.com
 * @version  1.0
 */
public class HandDraw
{
	//畫圖區(qū)的寬度 
	private final int AREA_WIDTH = 500;
	//畫圖區(qū)的高度
	private final int AREA_HEIGHT = 400;
	//下面的preX、preY保存了上一次鼠標(biāo)拖動事件的鼠標(biāo)座標(biāo)
	private int preX = -1;
	private int preY = -1;
	//定義一個右鍵菜單用于設(shè)置畫筆顏色
	JPopupMenu pop = new JPopupMenu();
	JMenuItem chooseColor = new JMenuItem("選擇顏色");
	//定義一個BufferedImage對象
	BufferedImage image = new BufferedImage(AREA_WIDTH , AREA_HEIGHT , 
		BufferedImage.TYPE_INT_RGB);
	//獲取image對象的Graphics
	Graphics g = image.getGraphics();
	private JFrame f = new JFrame("簡單手繪程序");
	private DrawCanvas drawArea = new DrawCanvas();
	//用于保存需要繪制什么圖形的字符串屬性
	private String shape = "";
	//用于保存畫筆顏色
	private Color foreColor = new Color(255, 0 ,0);
	public void init()
	{
		chooseColor.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent ae)
			{
				//下面代碼直接彈出一個模式的顏色選擇器對話框，并返回用戶選擇的顏色
				//foreColor = JColorChooser.showDialog(f , "選擇畫筆顏色" , foreColor);
				//下面代碼則可以彈出一個非模式的顏色選擇對話框，
				//并可以分別為“確定”按鈕、“取消”按鈕指定事件監(jiān)聽器
				final JColorChooser colorPane = new JColorChooser(foreColor);
				JDialog jd = JColorChooser.createDialog(f ,"選擇畫筆顏色",false, 
					colorPane, new ActionListener()
					{
						public void actionPerformed(ActionEvent ae)
						{
							foreColor = colorPane.getColor();
						}
					}, null);
				jd.setVisible(true);
			}
		});
		//將菜單項組合成右鍵菜單
		pop.add(chooseColor);
		//將右鍵菜單添加到drawArea對象中
		drawArea.setComponentPopupMenu(pop);
		//將image對象的背景色填充成白色
		g.fillRect(0 , 0 ,AREA_WIDTH , AREA_HEIGHT);
		drawArea.setPreferredSize(new Dimension(AREA_WIDTH , AREA_HEIGHT));
		//監(jiān)聽鼠標(biāo)移動動作
		drawArea.addMouseMotionListener(new MouseMotionAdapter()
		{
			//實現(xiàn)按下鼠標(biāo)鍵并拖動的事件處理器
			public void mouseDragged(MouseEvent e)
			{
				//如果preX和preY大于0
				if (preX > 0 && preY > 0)
				{
					//設(shè)置當(dāng)前顏色
					g.setColor(foreColor);
					//繪制從上一次鼠標(biāo)拖動事件點到本次鼠標(biāo)拖動事件點的線段
					g.drawLine(preX , preY , e.getX() , e.getY());
				}
				//將當(dāng)前鼠標(biāo)事件點的X、Y座標(biāo)保存起來
				preX = e.getX();
				preY = e.getY();
				//重繪drawArea對象
				drawArea.repaint();
			}
		});
		//監(jiān)聽鼠標(biāo)事件
		drawArea.addMouseListener(new MouseAdapter()
		{
			//實現(xiàn)鼠標(biāo)松開的事件處理器
			public void mouseReleased(MouseEvent e)
			{
				//松開鼠標(biāo)鍵時，把上一次鼠標(biāo)拖動事件的X、Y座標(biāo)設(shè)為-1。
				preX = -1;
				preY = -1;
			}
		});
		f.add(drawArea);
		f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		f.pack();
		f.setVisible(true);
	}
	public static void main(String[] args) 
	{
		new HandDraw().init();
	}
	//讓畫圖區(qū)域繼承JPanel類
	class DrawCanvas extends JPanel
	{
		//重寫JPanel的paint方法，實現(xiàn)繪畫
		public void paint(Graphics g)
		{
			//將image繪制到該組件上
			g.drawImage(image , 0 , 0 , null);
		}
	}
}