example14_15try.java

不错的教程 适合中高级人员的使用

//重新设计一个简单一点的

import java.awt.*;import java.awt.image.*;
import java.awt.event.*;import com.sun.image.codec.jpeg.*;
import java.util.*;import java.io.*;
class PaintCanvas extends Canvas 
{  int x=-1,y=-1;
   Vector v=new Vector();
   BufferedImage image;
   Graphics2D g2D;
   PaintCanvas()
   { 
	 setSize(300,300);setBackground(Color.cyan);
	 image=new BufferedImage(300,300,BufferedImage.TYPE_INT_RGB);
     g2D=image.createGraphics();
	 g2D.setColor(Color.white);g2D.fillRect(0,0,300,300);//把背景变成白色
	 g2D.setColor(Color.red);
	 g2D.drawLine(20,30,40,70);
	 g2D.drawOval(20,20,100,120);//说明程序没有问题，直接在图像上绘图是没问题的！
	 //不过图像底色确实是黑色的
	 g2D.setColor(Color.white);
	 g2D.fillOval(40,30,100,110);

   }
   public void paint(Graphics g)
   {
     g.drawImage(image,0,0,this);
   }
   public void update(Graphics g)
	{paint(g);}
}

class WindowCanvas extends Frame implements ActionListener
{
	PaintCanvas canvas=new PaintCanvas();
	Button button=new Button("save");
	WindowCanvas()
	{
		button.addActionListener(this);
		add(button,BorderLayout.NORTH);
		add(canvas,BorderLayout.CENTER);
		setBounds(100,100,400,400);
		setVisible(true);
		addWindowListener(new WindowAdapter()
		{
			public void windowClosing(WindowEvent e)
			{
				System.exit(0);
			}
		}
		);
	}
	public void actionPerformed(ActionEvent e)
	{
		try{JPEGImageEncoder encoder=JPEGCodec.createJPEGEncoder(new FileOutputStream("B.jpg"));
		     encoder.encode(canvas.image);
			}
		catch(Exception ee)	{}
	}
}
public class Example14_15TRY
{ public static void main(String args[])
  {new WindowCanvas();
   }
}