Drawing images in JComponent

Question

Hi,
I have an application laid out as Figure 1 depicts.
JFrame
|
| JMenuBar
|-----------------------------------------
| ------------------JPanel - appPanel
| |--------------------------------|
| | ---|------------------ JPanel - displayPanel
| | | |
| |----------------|---------------|
| |-------------------------- JComponent - jcanvas
|
| |--------------------------------|
| | ----|----------------------- JPanel - controlPanel
| | |
| |--------------------------------|
|
|--------------------------------------------
Figure 1
The problem I am having is that:
theJPanel (appPanel) contains two JPanels (displayPanel and controlPanel) and I am adding a JComponent called JCanvas
to the displayPanel and I use it to draw images on it of type BufferedImage. Now, the image is displayed without any problem
but when I resize the application (JFrame) I lose my image. I know the JCanvas (JComponent) is being redrawn because I can
temporarily see the image but something is overwriting the image. I have set appPanel, displayPanel, controlPanel to opaque
but I still loose the image.
Of point maybe, if I access the JMenuBar the image will appear less what part of the menu bar obscures it.
The appPanel, controlPanel, and displayPanel are created in the IDE. Where as, the JCanvas is a seperate class extending JCompoment
and it has it own paintComponent method to do the image rendering and is added to the displayPanel when instantiated.
What I don't understand is why isn't the image staying visible after a frame resize?
Thanks,
Bob

Answer 1

Hopefully this will fit.
You will have to provide your own image file.
* SwingPaintDemo2.java
* Created on Sep 27, 2008, 10:57:22 AM
* Company: 
* Copyright: Sep 27, 2008
* Version:
import javax.swing.SwingUtilities;
import javax.swing.JFrame;
import javax.swing.BorderFactory;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.JComponent;
* @author
public class SwingPaintDemo2 {
    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
    private static void createAndShowGUI() {
        System.out.println("Created GUI on EDT? " +
            SwingUtilities.isEventDispatchThread());
        JFrame f = new JFrame("Swing Paint Demo");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(new MyPanel());
        f.pack();
        f.setVisible(true);
class MyPanel extends JComponent {
    BufferedImage bi;
    File file;
    Dimension d = new Dimension();
    boolean fullScreen = false;
    public MyPanel() {
        setBorder(BorderFactory.createLineBorder(Color.black));
        file = new File("g://java/images/dido_img.jpg");
        try {
            bi = ImageIO.read(file);
        } catch (IOException ex) {
            Logger.getLogger(MyPanel.class.getName()).
                log(Level.SEVERE, null, ex);
    @Override
    public Dimension getPreferredSize() {
        return new Dimension(350, 350);
    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D) this.getGraphics();
        d = this.getPreferredSize();
        if (d.width == 0 || d.height == 0) {/* error */
        if (!fullScreen) {
            int px = (d.width - bi.getWidth()) / 2;
            int py = (d.height - bi.getHeight()) / 2;
            g2.drawImage(bi, null, px, py);
        } else {
            g2.drawImage(bi, 0, 0, d.width, d.height,
                0, 0, bi.getWidth(), bi.getHeight(), null);
}