How to add non-Transparent components to Transparent JFrame in java 1.5?

Question

I have a subclass of JFrame(it contains JButton, Title and Jpanel) and i added a JPanel to it. Jpanel occupies center portion of borderlayout. I want to make JPanel to be transparent(it should see through the Frame window).

As i am doing it for Java 1.5, I used JFrame.setOpacity(0.0f) to set transparency of Jframe. By doing this all Components of JFrame(ie. button, Title ahd jPanel) are using same alpha level. But I want only JPanel to be Transparent.

I experimented with JLayeredPane by changing Z-order with the same result.

I am open to use external libraries like JNA(JNA windowsUtil is also doing the same as setOpacity() method) and using classes of java7 or java6 as external libraries to my application .

I even gone through some previously asked questions with no help:

Opaque components on transparent Java windows

Java: Transparent Windows with non-transparent components?

Re-paint on translucent frame/panel/component.

Answer 1

Use JNA's WindowUtils.setWindowTransparent() method to start with a completely transparent window. Any pixels painted into that window will have their alpha component preserved.

JFrame f = ...
WindowUtils.setWindowTransparent(f, true);
// ensure JPanel content pane doesn't paint its (solid) background
f.getContentPane().setOpaque(false);
// Any other added components will be painted normally
f.getContentPane().add(new JButton("I'm opaque"));

This should deliver the desired results.

If you want your container to be semi-transparent, or other opacity combinations, you'll need to clarify your desired results.

Answer 2

Here is a small example with two labels. One being fully opaque while the other is semi-transparent. This can work as well with JPanel, but for demonstration-purposes, it is more examplative with JLabel:

import java.awt.BorderLayout;
import java.awt.Color;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.SwingUtilities;

import com.sun.awt.AWTUtilities;

public class Test3 {

    protected static void initUI() {
        JFrame frame = new JFrame("test");
        frame.setUndecorated(true);
        AWTUtilities.setWindowOpaque(frame, false);
        JLabel label = new JLabel("Hello NOT transparent label");
        label.setOpaque(true);
        label.setBackground(new Color(255, 0, 0));
        JLabel transLabel = new JLabel("Hello transparent label");
        transLabel.setOpaque(true);
        transLabel.setBackground(new Color(255, 0, 0, 50));
        frame.setLocationByPlatform(true);
        frame.getContentPane().add(label);
        frame.getContentPane().add(transLabel, BorderLayout.SOUTH);
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                initUI();
            }
        });
    }
}