Java实现隐形画图板开发

      
  有一次在课上无意中看了东哥演示的隐形画图板，感觉比较有趣，于是头脑发热，回去就马上动手，话了 一晚上时间，编出一个比较丑陋的所谓的隐形画图板。其实说吧，这个画图板就是一个骗人的东西，它的原理就是先把当前屏幕图片截下来，然后再画到窗体上，把窗体大小设置成屏幕大小，去掉窗体上的关闭按钮，就得到了一个隐形画图板了。接下来逐步介绍怎么实现这个画图板的几个窗用的功能。

一、将窗体设置成屏幕大小，该过程使用了Java中的一个工具Toolkit 代码如下：

                  Toolkit toolkit = Toolkit.getDefaultToolkit();
		Dimension dm = toolkit.getScreenSize();
		this.setSize(dm);

二、去掉窗体的关闭按钮，用到了Java自带的一个窗体修饰方法setUndecorated(true)，参数true表示不可修饰，得到一个空白窗体，代码很简单，就一行：
                 

 this.setUndecorated(true);

三、获取当前屏幕背景图片，并保存到工程下，该过程用到了Java自带的Robot和ImageIO方法；具体代码实现如下：

Rectangle rect = new Rectangle(dm);
Robot robot = new Robot();

BufferedImageimage=robot.createScreenCapture（rect）;                                                     
try {
ImageIO.write(image, "jpg", new File("C:\\Users\\Administrator\\workspace\\隐形画图板\\img\\" + "a" + ".jpg"));
} catch (IOException ef) {
// TODO Auto-generated catch block
ef.printStackTrace();
	}
g.drawImage(image, 0 , 0, dm.width,  dm.height,Color.white, null);
} catch (AWTException ea) {
// TODO Auto-generated catch block
ea.printStackTrace();
}

//主窗体
package cjl.deaw1;

import java.awt.*;
import java.awt.image.BufferedImage;
import java.awt.image.RenderedImage;
import java.io.File;
import java.io.IOException;

import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;

/**
 * 画图板界面类
 * 
 * @author Administrator
 * 
 */
public class DrawUI extends JFrame {
	BufferedImage image;
	Image image1;
	public static void main(String args[]) {

		new DrawUI();

	}



	/**
	 * 初始化界面的方法
	 */
	public DrawUI() {
		Toolkit toolkit = Toolkit.getDefaultToolkit();
		Dimension dm = toolkit.getScreenSize();
		JPanel panel=new JPanel();
		panel.setBackground(Color.WHITE);
		panel.setPreferredSize(dm);
		this.setSize(dm);
		FlowLayout fl = new FlowLayout();
		this.setUndecorated(true);
		this.setLayout(fl);
		this.setAlwaysOnTop(true);
		this.setDefaultCloseOperation(3);
		this.add(panel );
		this.setVisible(true);
		// 从窗体上获取画布对象
		// 获取窗体在屏幕上所占据的区域，这块区域是允许改变颜色的
		Graphics g = this.getGraphics();
//		int [] x={100,150,300};
//		int [] y={100,200,300};
//		g.drawPolygon(x, y, 3);
		
//		Graphics2D g2d = (Graphics2D) this.getGraphics();
		// 创建鼠标监听器对象
		DrawListener dlis = new DrawListener(g,this);
		// 给窗体加上鼠标监听器
		this.addMouseListener(dlis);
		try {
			Rectangle rect = new Rectangle(dm);
			Robot robot = new Robot();
			BufferedImage image = robot.createScreenCapture(rect);
			  
				try {
					ImageIO.write(image, "jpg", new File("C:\\Users\\Administrator\\workspace\\隐形画图板\\img\\" + "a" + ".jpg"));
				} catch (IOException ef) {
					// TODO Auto-generated catch block
					ef.printStackTrace();
				}
				g.drawImage(image, 0 , 0, dm.width,  dm.height,Color.white, null);
		} catch (AWTException ea) {
			// TODO Auto-generated catch block
			ea.printStackTrace();
		}

	}

}

//监听器
package cjl.deaw1;

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;

import javax.swing.JOptionPane;

/**
 * 画板的监听器，实现鼠标监听器接口
 * 
 * @author Administrator
 * 
 */
public class DrawListener implements MouseListener {

	private int x1, y1, x2, y2;
	private Graphics gr;
	public float stroke;
	DrawUI drawUI;
	public DrawListener(Graphics gr, DrawUI drawUI) {
		this.gr = gr;
		this.drawUI=drawUI;

	}

	public void mousePressed(MouseEvent e) {
		// 获取鼠标按下时候光标的位置
		x1 = e.getX();
		y1 = e.getY();
		if (e.isMetaDown()) {
			JOptionPane.showMessageDialog(drawUI, "你你确定要退出吗？");
			System.exit(0);
		}
		if (e.isControlDown())
			System.out.println();
		
//		draw(x1, y1, 100, 1);
		
		

	}
	

	public void mouseReleased(MouseEvent e) {
		// 获取鼠标释放时候光标的位置
		x2 = e.getX();
		y2 = e.getY();
		for (int i = 0; i <= 50; i++) {
			gr.setColor(new Color(155 + 2 * i, 100 + 2 * i, 40 + 2 * i));
			gr.fillOval(Math.min(x1, x2) + i, Math.min(y1, y2), 100 - 2 * i,
					160 - 2 * i);

		}
	}

	public void mouseEntered(MouseEvent e) {
		// System.out.println("mouseEntered");
	}

	public void mouseExited(MouseEvent e) {
		// System.out.println("mouseExited");
	}

	public void mouseClicked(MouseEvent e) {
		

		// System.out.println("mouseClicked");
	}

	public void draw(double x0, double y0, int L, int n) {
		double x1 = 0, y1 = 0;
		if (n <= 0) {
			return;
		} else {
			for (int i = 0; i <= 800; i++) {
				try {
					Thread.sleep(5);
				} catch (InterruptedException e1) {
					// TODO Auto-generated catch block
					e1.printStackTrace();
				}
				if (i <= 200) {
					L = i;
					gr.setColor(new Color(255 - i, i, i));
					gr.fillOval((int) (x0 + L), (int) y0, 10, 10);

				}
				if (i >= 200 && i <= 400) {
					L = i - 200;
					gr.setColor(new Color(455 - i, i - 200, i - 150));
					gr.fillOval((int) (x0 + 200), (int) y0 + L, 10, 10);

				}
				if (i >= 400 && i <= 600) {
					L = 600 - i;
					gr.setColor(new Color(655 - i, i - 400, i - 350));
					gr.fillOval((int) x0 + L, (int) y0 + 200, 10, 10);

				}
				if (i >= 600 && i <= 800) {
					L = 800 - i;
					gr.setColor(new Color(855 - i, i - 600, i - 550));
					gr.fillOval((int) x0, (int) y0 + L, 10, 10);

				}
				x1 = Math.sin((x0 + i) / 4) * 100;
				y1 = Math.sin((y0 + i) / 4) * 100;
				// System.out.println("x1:" + x1 + "\n" + "y1;" + y1);
			}

		}
		draw(y1 + 140, y1 + 140, L, n - 1);
	}
}