Transparent JSplitPane repaint issue

Question

Hi,
I have a split pane added to the content pane of a JFrame and an image loaded in a layer below that of the content pane. All components including the content pane are set to transparent.
This frame loads up fine, but as soon as the splitter bar is moved, the split pane components mess up.
Looks like on repaint, the underlying image is not being repainted. I'm using JDK1.4.2_06. Does anyone know how I can get this to repaint right?
Thanks in advance,
Regards,
Pramod
A sample program that shows this problem:
import java.awt.Color;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JSplitPane;
import javax.swing.JTree;
public class TSplitter
     extends JFrame
     public TSplitter() {
          init();
     private void init() {
          // Left component is a tree within a scroll pane, all
          // transparent
          JTree tree = new JTree();
          tree.setOpaque(false);
          JScrollPane leftComponent = new JScrollPane();
          leftComponent.getViewport().add(tree);
          leftComponent.getViewport().setOpaque(false);
          leftComponent.setOpaque(false);
          // Right side component is just a line of text, with a
          // transparent background
          JLabel rightComponent = new JLabel();
          rightComponent.setText("Right side text");
          rightComponent.setOpaque(false);
          // Split pane constructed with a zero alpha value background,
          // to make this too transparent
          JSplitPane splitPane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT,
                    leftComponent, rightComponent);
          splitPane.setBackground(new Color(0, 0, 0, 0));
          // Split pane added to the content pane, and the content pane
          // too made transparent.
          getContentPane().add(splitPane);
          ((JPanel)getContentPane()).setOpaque(false);
          // Add a background image into the layered pane of the JFrame
          try {
               ImageIcon ii = new ImageIcon("C:\\watermark.jpg");
               JLabel imageLabel = new JLabel(ii);
               imageLabel.setSize(ii.getIconWidth(), ii.getIconHeight());
               // Load image in a layer below FRAME_CONTENT_LAYER
               this.getLayeredPane().add(imageLabel, new Integer(-30001));
          catch (Exception ex) {
               System.out.println("Failed to load watermark... : " + ex);
               ex.printStackTrace();
          // Position and show
          setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          setBounds(100, 100, 400, 400);
          show();
     public static void main(String[] args) {
          new TSplitter();
}

Answer 1

I've never had luck using alpha values, especially an alpha value of 0. Get rid of that and you will see an improvement.
However it still won't work. When all you components are transparent the background doesn't get repainted correctly. So instead of using a LayeredPane to paint your image, you can add the image directly to the content pane as follows:
final ImageIcon ii = new ImageIcon("mong.jpg");
JPanel panel = new JPanel(new BorderLayout())
     protected void paintComponent(Graphics g)
          super.paintComponent(g);
               g.drawImage(ii.getImage(), 0, 0, null);
setContentPane( panel );Note, it may be even easier to override the paintComponent() method of the splitPane to paint the image. That way you don't have to play with the contentPane, other than to change its background color.