Copying BufferedImage to clipboard fails

Question

The clipboard is giving me some trouble... If I copy an image selection with transparency data and then create a BufferedImage from the clipboard contents (paste), then everything works fine everywhere. However if I have a BufferedImage with transparency data that I want to SET to the clipboard (copy) then I observe two different behaviors between Ubuntu and Windows XP -- both incorrect.
On Ubuntu:
getTransferDataFlavors of my Transferable is called once. isDataFlavorSupported and getTransferData are never called. The clipboard is unaltered. No exception is thrown -- nothing. It just silently fails to do anything. Calling Toolkit.getDefaultToolkit().getSystemClipboard().getAvailableDataFlavors() shows me that DataFlavor.imageFlavor is indeed present.
On Windows:
My getTransferData is indeed called and the clipboard is modified. However, the image is set on a BLACK background -- the transparency data is lost.
Relevant code portions look like:
btnCopy.addActionListener(new ActionListener(){
               public void actionPerformed(ActionEvent e){
                    CopyableImage img = new CopyableImage(frame.getImage());
                    Toolkit.getDefaultToolkit().getSystemClipboard().setContents(img, null);
          });Where frame.getImage is a BufferedImage of type ARGB, with a transparent background
private static class CopyableImage implements Transferable {
        private BufferedImage image;
        public CopyableImage(BufferedImage image) {
            this.image = image;
        // Returns supported flavors
        public DataFlavor[] getTransferDataFlavors() {
            return new DataFlavor[]{DataFlavor.imageFlavor};
        // Returns true if flavor is supported
        public boolean isDataFlavorSupported(DataFlavor flavor) {
            return DataFlavor.imageFlavor.equals(DataFlavor.imageFlavor);
        // Returns image
        public BufferedImage getTransferData(DataFlavor flavor) throws UnsupportedFlavorException, IOException {
            if (!DataFlavor.imageFlavor.equals(flavor)) {
                throw new UnsupportedFlavorException(flavor);
            return image;
    }Any ideas...?
Additional Notes:
I'm am running Java 1.6
My paste destination is in GIMP, on a new image with transparent background.
Edited by: MichaelDGagnon on Dec 14, 2008 11:18 AM

Answer 1

A fully self contained example which continues to replicate the problems observed for me is as follows. Paste works (slowly) and copy fails
import java.io.IOException;
import java.net.*;
import java.awt.*;
import java.awt.image.*;
import java.awt.event.*;
import javax.swing.*;
import javax.imageio.*;
import java.awt.datatransfer.*;
public class CopyTest extends JPanel{
     public static void main(String args[]) throws Exception{
          final CopyTest copyTest = new CopyTest();
          JFrame f = new JFrame();
          f.addWindowListener(new WindowListener(){
               public void windowClosed(WindowEvent e){}
               public void windowClosing(WindowEvent e){ System.exit(0); }
               public void windowIconified(WindowEvent e){}
               public void windowDeiconified(WindowEvent e){}
               public void windowActivated(WindowEvent e){}
               public void windowDeactivated(WindowEvent e){}
               public void windowOpened(WindowEvent e){}
          f.setLayout(new BorderLayout());
          JButton btnCopy = new JButton("Copy");
          JButton btnPaste = new JButton("Paste");
          JPanel southPanel = new JPanel();
          southPanel.add(btnCopy);
          southPanel.add(btnPaste);
          f.add(copyTest, BorderLayout.CENTER);
          f.add(southPanel, BorderLayout.SOUTH);
          btnCopy.addActionListener(new ActionListener(){
               public void actionPerformed(ActionEvent e){ copyTest.copy(); }
          btnPaste.addActionListener(new ActionListener(){
               public void actionPerformed(ActionEvent e){ copyTest.paste(); }
          f.setSize(320, 240);
          f.setVisible(true);
     private static final int SQUARE_SIZE=6;
     private BufferedImage image;
     // Constructor
     public CopyTest() throws Exception{
          this.image = ImageIO.read(new URL("http://forums.sun.com/im/duke.gif"));
     // Copy
     public void copy(){
          Toolkit.getDefaultToolkit().getSystemClipboard().setContents(
                    new Transferable(){
                         public DataFlavor[] getTransferDataFlavors() { return new DataFlavor[]{DataFlavor.imageFlavor}; }
                         public boolean isDataFlavorSupported(DataFlavor flavor) { return DataFlavor.imageFlavor.equals(DataFlavor.imageFlavor); }
                         public Object getTransferData(DataFlavor flavor) throws UnsupportedFlavorException, IOException {
                           if(!DataFlavor.imageFlavor.equals(flavor)){ throw new UnsupportedFlavorException(flavor); }
                           return image;
                    , null);
     // Paste
     public void paste(){
          // Get the contents
          BufferedImage clipboard = null;
          Transferable t = Toolkit.getDefaultToolkit().getSystemClipboard().getContents(null);
          try {
            if (t != null && t.isDataFlavorSupported(DataFlavor.imageFlavor)) {
                 clipboard = (BufferedImage)t.getTransferData(DataFlavor.imageFlavor);
        } catch (Exception e) { e.printStackTrace(); }
        // Use the contents
        if(clipboard != null){
               image = clipboard;
               repaint();
     // Paint
     public void paint(Graphics g){
          // Paint squares in the background to accent transparency
          g.setColor(Color.LIGHT_GRAY);
          g.fillRect(0, 0, getWidth(), getHeight());
          g.setColor(Color.DARK_GRAY);
          for(int x=0; x<(getWidth()/SQUARE_SIZE)+1; x=x+1){
               for(int y=0; y<(getHeight()/SQUARE_SIZE)+1; y=y+1){
                    if(x%2 == y%2){ g.fillRect(x*SQUARE_SIZE, y*SQUARE_SIZE, SQUARE_SIZE, SQUARE_SIZE); }
          // Paint the image
          g.drawImage(image, 0, 0, this);
}