import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
/**
 * 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
{
	//畫圖區的寬度 
	private final int AREA_WIDTH = 500;
	//畫圖區的高度
	private final int AREA_HEIGHT = 400;
	//下面的preX、preY保存了上一次鼠標拖動事件的鼠標座標
	private int preX = -1;
	private int preY = -1;
	//定義一個右鍵菜單用于設置畫筆顏色
	PopupMenu pop = new PopupMenu();
	MenuItem redItem = new MenuItem("紅色");
	MenuItem greenItem = new MenuItem("綠色");
	MenuItem blueItem = new MenuItem("藍色");
	//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 Frame f = new Frame("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()
	{
		//定義右鍵菜單的事件監聽器。
		ActionListener menuListener = new ActionListener()
		{
			public void actionPerformed(ActionEvent e)
			{
				if (e.getActionCommand().equals("綠色"))
				{
					foreColor = new Color(0 , 255 , 0);
				}
				if (e.getActionCommand().equals("紅色"))
				{
					foreColor = new Color(255 , 0 , 0);
				}
				if (e.getActionCommand().equals("藍色"))
				{
					foreColor = new Color(0 , 0 , 255);
				}
			}
		};
		//為三個菜單添加事件監聽器
		redItem.addActionListener(menuListener);
		greenItem.addActionListener(menuListener);
		blueItem.addActionListener(menuListener);
		//將菜單項組合成右鍵菜單
		pop.add(redItem);
		pop.add(greenItem);
		pop.add(blueItem);
		//將右鍵菜單添加到drawArea對象中
		drawArea.add(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));
		//監聽鼠標移動動作
		drawArea.addMouseMotionListener(new MouseMotionAdapter()
		{
			//實現按下鼠標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)
				{
					//設置當前顏色
					g.setColor(foreColor);
					//繪制從上一次鼠標拖動事件點到本次鼠標拖動事件點的線段
					g.drawLine(preX , preY , e.getX() , e.getY());
				}
				//將當前鼠標事件點的X、Y座標保存起來
				preX = e.getX();
				preY = e.getY();
				//重繪drawArea對象
				drawArea.repaint();
			}
		});
		//監聽鼠標事件
		drawArea.addMouseListener(new MouseAdapter()
		{
			//實現鼠標松開的事件處理器
			public void mouseReleased(MouseEvent e)
			{
				//彈出右鍵菜單
				if (e.isPopupTrigger())
				{
					pop.show(drawArea , e.getX() , e.getY());
				}
				//松開鼠標鍵時，把上一次鼠標拖動事件的X、Y座標設為-1。
				preX = -1;
				preY = -1;
			}
		});
		f.add(drawArea);
		f.pack();
		f.setVisible(true);
	}
	public static void main(String[] args) 
	{
		new HandDraw().init();
	}
	class DrawCanvas extends Canvas
	{
		//重寫Canvas的paint方法，實現繪畫
		public void paint(Graphics g)
		{
			//將image繪制到該組件上
			g.drawImage(image , 0 , 0 , null);
		}
	}
}