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javaswingiconsrenderingjtree

JTree set transparency of Icon

I want to give a visual indication that a node has been transferred to clipboard with a "Cut" action. One intuitive look used by at least one proprietary OS is to make this the same image, but slightly transparent.

I'd quite like to know whether it is in fact possible somehow to use the icons used by the Windoze OS (W7)... but I'd be more intrigued if it were possible to interfere in some way (in the renderer) with the Icon, by somehow messing with the Graphics object used by Icon.paintIcon() ... just for a given node, obviously. I'm not clear where an Icon goes hunting for the Graphics object it uses when it is painted ... any enlightenment would be most welcome.

later

Many thanks to MadProgrammer. Spotted this possibility as a way of extracting obfuscated visuals with a view to their manipulation: https://home.java.net/node/674913 ... it works. Putting code here in case of broken link...

public class IconTest {

    public static void main(String[] args) {
        Icon leafIcon = UIManager.getIcon("Tree.leafIcon"); 
        // ... ("Tree.closedIcon") ("Tree.openIcon")

        BufferedImage img1 = new BufferedImage(leafIcon.getIconWidth(),
                leafIcon.getIconHeight(), BufferedImage.TYPE_INT_RGB);

        Graphics g = img1.createGraphics();
        g.drawImage(((ImageIcon) leafIcon).getImage(), 0, 0, null);
        g.dispose();

        try {
            ImageIO.write(img1, "PNG", new File("leafIcon.png"));
        } catch (IOException e) {
            System.out.println("Error writing to file leafIcon" + ", e = " + e);
            System.exit(0);
        }

    }

}

Then use MadProgrammer's technique to alter the image in any way one likes: change transparency, colour, etc. Great stuff.

Solution

  • I'd quite like to know whether it is in fact possible somehow to use the icons used by the Windoze OS (W7)

    FileSystemView#getSystemIcon will give you the OS's icon representation of a given File, for example...

    Icon icon = FileSystemView.getFileSystemView().getSystemIcon(new File("ThatImportantDoc.docx"));

    I want to give a visual indication that a node has been transferred to clipboard with a "Cut" action. One intuitive look used by at least one proprietary OS is to make this the same image, but slightly transparent.

    You need to paint the previous Icon to BufferedImage, which has had a AlphaComposite applied to it, for example

    BufferedImage img = new BufferedImage(icon.getIconWidth(), icon.getIconHeight(), BufferedImage.TYPE_INT_ARGB);
Graphics2D g2d = img.createGraphics();
g2d.setComposite(AlphaComposite.SrcOver.derive(0.5f));
icon.paintIcon(null, g2d, 0, 0);
g2d.dispose();

    You then need to wrap the resulting BufferedImage in a ImageIcon, which allows you to pass the image as a Icon to the rest of the API.

    Faded Icon

    JPanel panel = new JPanel();
panel.add(new JLabel(icon));
panel.add(new JLabel(new ImageIcon(img)));
JOptionPane.showMessageDialog(null, panel, "Icon", JOptionPane.PLAIN_MESSAGE);

    To get this to finally work, you will need to provide a TreeCellRenderer capable of supporting your functionality. Have a look at How to Use Trees for more details