为什么bufferedImage setColor不起作用

Jerry_shower 2011-02-12 03:53:27

各位大侠：
我的测试思路是这样的，在JFrame里嵌套一个Jpanel,在Jpanel里展现一个白色的背景色。

m_canvas = new BufferedImage(400, 450, BufferedImage.TYPE_INT_BGR);
g2d =(Graphics2D)m_canvas.getGraphics();
g2d.setColor(Color.white);
g2d.fillRect(0, 0, this.getWidth(), this.getHeight());
m_canvas.flush();

调用Jpanel.paint()方法，用 g.drawImage(m_canvas, 0, 0, null);画出来，可是运行结果是黑色的，请高手指教错再哪里？





package JFrameTest;



import JFrameTest.ScrollablePicture;



import java.awt.Color;

import java.awt.Dimension;

import java.awt.Graphics;

import java.awt.Graphics2D;

import java.awt.Image;

import java.awt.Point;

import java.awt.Toolkit;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import java.awt.geom.AffineTransform;

import java.awt.image.BufferedImage;

import java.io.IOException;



import javax.swing.BoxLayout;

import javax.swing.ImageIcon;

import javax.swing.JButton;

import javax.swing.JFrame;

import javax.swing.JPanel;

import javax.swing.JScrollPane;



public class ImageDemo extends JFrame {



	private MainCavas panel;

	private boolean isDrawRect = false;



	public ImageDemo() {



		Dimension d = Toolkit.getDefaultToolkit().getScreenSize();

		setBounds((d.width - 800) / 2, (d.height - 600) / 2, 800, 600);

		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

		setLayout(null);



		panel = new MainCavas();



		JButton b1 = new JButton("1");

		b1.addActionListener(new ActionListener() {

			public void actionPerformed(ActionEvent e) {

				System.out.println("calling b1");

			}

		});

		b1.setBounds(2, 2, 150, 30);

		this.add(b1);



		JButton b2 = new JButton("2");

		b2.addActionListener(new ActionListener() {

			public void actionPerformed(ActionEvent e) {

				System.out.println("calling b2");

			}

		});

		b2.setBounds(200, 2, 150, 30);

		this.add(b2);



		panel.setBounds(2, 70, 400, 450);

		this.add(panel);

		setVisible(true);

	}



	public BufferedImage getCopy(BufferedImage in) {

		BufferedImage temp = new BufferedImage(in.getWidth(), in.getHeight(),

				BufferedImage.TYPE_INT_RGB);

		Graphics2D g2d = temp.createGraphics();

		g2d.drawImage(in, null, 0, 0);

		return temp;

	}





	public static void main(String[] args) throws IOException {

		new ImageDemo();

	}



	class MainCavas extends JPanel {

		public BufferedImage m_canvas;

		public ImageIcon m_mainIcon;

		public JScrollPane m_scrollPane = new JScrollPane();

		public AffineTransform t;

		public BufferedImage m_backGround;

		public Graphics2D g2d;

		public ScrollablePicture m_picture;

		

		public int clc=0;



		public MainCavas() {

			m_canvas = new BufferedImage(400, 450, BufferedImage.TYPE_INT_BGR);

			g2d =(Graphics2D)m_canvas.getGraphics();

			g2d.setColor(Color.white);

			g2d.fillRect(0, 0, this.getWidth(), this.getHeight());

			m_canvas.flush();

			

		}



		public void paint(Graphics g)

		{

//			g.drawImage(m_canvas, 0, 0, Color.red, null);

			g.drawImage(m_canvas, 0, 0, null);

		}

//		public void paintComponent(Graphics g) {

//			System.out.println("calling paintComponent...");

//			super.paintComponent(g);

//			

//				 

//		}

	}

}