mousedraw.java

中国水利水电出版社java程序设计教程,附源码

//MouseDraw

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

public class MouseDraw
{
	public static void main(String[] args)
	{
		MouseFrame frame = new MouseFrame();
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.show();
	}
}

class MouseFrame extends JFrame
{
	public MouseFrame()
	{
		setTitle("利用鼠标画图");
		setSize(WIDTH, HEIGHT);
		
		// 将panel加入到frame
		MousePanel panel = new MousePanel();
		Container contentPane = getContentPane();
		contentPane.add(panel);
	}
	
	public static final int WIDTH = 300;
	public static final int HEIGHT = 200;  	
}

class MousePanel extends JPanel
{
	public MousePanel()
	{
		//初始化链表
		faces = new ArrayList();
		facetypes = new ArrayList();

		//初始化当前图像位置
		current = null;
		
		//加载图像
		String imageName = "smile.gif";
		smileimg = Toolkit.getDefaultToolkit().getImage(imageName);
		imageName = "cry.gif";
		cryimg = Toolkit.getDefaultToolkit().getImage(imageName);
		MediaTracker tracker = new MediaTracker(this);
		tracker.addImage(smileimg, 0);
		tracker.addImage(cryimg, 1);
		try
		{
			tracker.waitForID(0);
			tracker.waitForID(1);
		}
		catch (InterruptedException exception) {}

		//得到图像的高度和宽度
		imageWidth = smileimg.getWidth(this);
		imageHeight = smileimg.getWidth(this);

		//注册监听器
		addMouseListener(new MouseHandler());
		addMouseMotionListener(new MouseMotionHandler());
	}
	
	public void paintComponent(Graphics g)
	{
		super.paintComponent(g);

		//显示当前光标位置
		String text = "鼠标指针位置：" + mousex + "：" + mousey;
		g.drawString(text, 10, 10);

		//显示图像
		for (int i = 0; i < faces.size(); i++)
		{
			//得到图像位置
			int x = (int)((Rectangle)faces.get(i)).getX();
			int y = (int)((Rectangle)faces.get(i)).getY();

			//得到图像类型
			text = (String)(facetypes.get(i));

			if(text.equals("smile"))
				g.drawImage(smileimg, x, y, null);
			else
				g.drawImage(cryimg, x, y, null);
		}
	}
	
	//查找某个点是否在链表faces中的某个矩形内部
	public Rectangle search(Point pt)
	{
		for (int i = 0; i < faces.size(); i++)
		{
			Rectangle rect = (Rectangle)faces.get(i);
			if (rect.contains(pt)) 
				return rect;
		}
		
		return null;
	}
	
	//将以点pt为中心，以图像大小为高度和宽度的矩形加入链表faces中
	public void add(Point pt)
	{
		//取得点pt的坐标
		int x = (int)pt.getX();
		int y = (int)pt.getY();
		
		//生成矩形
		current = new Rectangle(
			x - imageWidth / 2,
			y - imageHeight / 2,
			imageWidth,
			imageHeight);

		//将生成的矩形加入链表faces中
		faces.add(current);
		//将图像类型加入链表facetypes中
		facetypes.add(facetype);

		repaint();
	}
	
	//修改图像的类型
	public void modify(Rectangle rect)
	{
		if (rect == null) return;

		int index = faces.indexOf(rect);
		String text = (String)(facetypes.get(index));

		if(text.equals("smile"))
			facetypes.set(index, "cry");
		else
			facetypes.set(index, "smile");
		
		repaint();
	}
	
	private ArrayList faces;
	private ArrayList facetypes;
	private Rectangle current;
	private Image smileimg;
	private Image cryimg;
	private int imageWidth;
	private int imageHeight;
	private String facetype;
	private int mousex,mousey;
	
	private class MouseHandler extends MouseAdapter
	{
		public void mousePressed(MouseEvent event)
		{
			//得到鼠标光标的当前位置
			mousex = event.getX();
			mousey = event.getY();

			//查找当前位置是否已有图像
			current = search(event.getPoint());
			if (current == null)
			{
				//添加一个“笑脸”图像
				facetype = "smile";
				add(event.getPoint());
			}
			else
				//对图像进行切换
				modify(current);
		}
	}
	
	private class MouseMotionHandler
		implements MouseMotionListener
	{
		public void mouseMoved(MouseEvent event)
		{
			//得到鼠标光标的当前位置
			mousex = event.getX();
			mousey = event.getY();

			repaint();
		}
		
		public void mouseDragged(MouseEvent event)
		{
			//得到鼠标光标的当前位置
			mousex = event.getX();
			mousey = event.getY();

			// 拖动图像
			current.setFrame(
				mousex - imageWidth / 2,
				mousey - imageHeight / 2,
				imageWidth,
				imageHeight);

			repaint();
		}
	}
}