Help setPreferredSize and resizing a frame

Question

Hey,
I have an internal JFrame that contains a JPanel which contains an image. The JPanel is the only compnent of the internal JFrame and must take up the whole of the space in the frame. The image must take up the whole of the Jpanel.
At the moment the image is drawn in the paint component part of the JPanel:
     // draw the racing track
     g.drawImage(track, 0, 0, imageWidth, imageHeight, this);
I set the preferred size of the JPanel so that the JFrame fits exactly around the image. This is to avoid clipping that would occur if i set the frame to the size of the image. This is implemented in the constructor of the JPanel :
// track is the image i am trying to draw
     imageWidth = track.getWidth(this);
     imageHeight = track.getHeight(this);
     setPreferredSize(new Dimension(imageWidth, imageHeight));
In the JInternalFrame I extend I call the pack() method; I believe this is what sets the frame to the right size so that no clipping occurs.
This works fine; the image currently appears with no clipping. However now I want to resize the internal frame. When this happens I want the image to be resized so that it can appear larger or smaller but it must maintain its original proportions.
I have the following event listener in place in the class that creates all of the internal frames :
tFrame.addComponentListener(new ComponentAdapter() {
public void componentResized(ComponentEvent evt) {
tFrameComponentResized(evt);
private void tFrameComponentResized(ComponentEvent evt) {
     trackWidth = tFrame.getWidth();
     trackHeight = tFrame.getHeight();
I am not sure how to continue from here. Any help would be greatly appreciated!!
Thanks Guys (and gals!)
Alex.

Answer 1

I have no idea if this is what you were looking for :import javax.swing.*;
import java.awt.*;
import java.awt.geom.AffineTransform;
import java.net.URL;
import java.net.MalformedURLException;
public class ResizableImage extends JPanel {
     private Image theImage;
     public ResizableImage(Image anImage) {
          if (anImage.getWidth(null) == 0) throw new IllegalArgumentException("Image's width is null");
          if (anImage.getHeight(null) == 0) throw new IllegalArgumentException("Image's height is nul");
          theImage = anImage;
     public Dimension getPreferredSize() {
          return new Dimension(theImage.getWidth(null), theImage.getHeight(null));
     protected void paintComponent(Graphics g) {
          super.paintComponents(g);
          Graphics2D g2D = (Graphics2D)g;
          Dimension available = getSize();
          if (available.width * available.height == 0) return;
          Dimension image = new Dimension(theImage.getWidth(null), theImage.getHeight(null));
          if (image.width * image.height == 0) return;
          if (image.equals(available)) {
               g2D.drawImage(theImage, 0, 0, null);
               return;
          double scale;
          if (available.height * image.width < available.width * image.height) {
               scale = (double)available.height / (double)image.height;
          } else {
               scale = (double)available.width / (double)image.width;
          g2D.drawImage(theImage, AffineTransform.getScaleInstance(scale, scale), null);
     public static void main(String[] args) {
          try {
               final JFrame frame = new JFrame("Resizable image");
               frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
               URL imageUrl = new URL("http://java.sun.com/docs/books/tutorial/uiswing/components/example-1dot4/images/Bird.gif");
               frame.setContentPane(new ResizableImage(new ImageIcon(imageUrl).getImage()));
               SwingUtilities.invokeLater(new Runnable() {
                    public void run() {
                         frame.pack();
                         frame.show();
          } catch (MalformedURLException e) {
               e.printStackTrace();
}