Question

I am using the following code to set a tray icon in Windows and Linux. It works wonderful in Windows and works okay in Linux. In Linux (Ubuntu) I have my panel set to be (somewhat) transparent and when I add a GIF (with a transparent background) the background of the icon shows up all grey and ugly (see image, green diamond ‘!’)….Any ideas on how to make the GIF image I am adding ‘keep’ its transparent background?

alt text http://unarm.org/stackoverflow/panel_task.jpg

and the image I am using, if you’d like to test:

alt text http://unarm.org/stackoverflow/green_info.gif

import java.awt.*; import java.awt.event.*;  public class TrayFun {     static class ShowMessageListener implements ActionListener {     TrayIcon trayIcon;     String title;     String message;     TrayIcon.MessageType messageType;     ShowMessageListener(         TrayIcon trayIcon,         String title,         String message,         TrayIcon.MessageType messageType) {       this.trayIcon = trayIcon;       this.title = title;       this.message = message;       this.messageType = messageType;     }     public void actionPerformed(ActionEvent e) {       trayIcon.displayMessage(title, message, messageType);     }   }    public static void main(String args[]) {     Runnable runner = new Runnable() {       public void run() {         if (SystemTray.isSupported()) {           final SystemTray tray = SystemTray.getSystemTray();           Image image = Toolkit.getDefaultToolkit().getImage('green_info.png');           PopupMenu popup = new PopupMenu();           final TrayIcon trayIcon = new TrayIcon(image, 'The Tip Text', popup);           trayIcon.setImageAutoSize(true);            MenuItem item = new MenuItem('Close');       item.addActionListener(new ActionListener() {             public void actionPerformed(ActionEvent e) {           tray.remove(trayIcon);             }       });           popup.add(item);           try {             tray.add(trayIcon);           } catch (AWTException e) {             System.err.println('Can't add to tray');           }         } else {           System.err.println('Tray unavailable');         }       }     };     EventQueue.invokeLater(runner);   } } 

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Answer 1

Chances are this problem cannot be resolved. It depends on wether Java is doing a good job in creating the tray subwindow in Linux or not. If Jave does it wrong, transparency is already lost when the image is drawn.

1. What is the real background value of the icon you are using? Is it the gray tone shown above? Set it to purple to see if the transparency of the image is used (Java defaults to gray background) or not.

2. Make sure you tried both transparency options of PNG: transparent color index as well as alpha channel. Alpha channel is very common in Linux, not so in the Windows world.

3. The resolution of your icon is too small. Do it in 64×64 or better 128×128. AFAIK there is no standard resolution for tray icons, and even if so, it is certainly not 16×16.

4. Another format you could try is SVG. Only try that after making sure that the transparency of the image is the problem (see 1).

See here for background information on this issue: http://www.rasterman.com/index.php?page=News (scroll down to 2 February 2006)