Translucent JPopupMenu inside a Translucent Window - alternative?

问题

I'm not sure if this is possible, but is there a way to safely allow popups to be translucent even when the parent container is also translucent?

If not, what would be wise alternative to use or extend instead of JPopupMenu?

Note: Translucent refers to a component not 'having a background', similar to the effect of setOpaque(false);. Thanks.

From a forum answer by user camickr in 2009:

I don't know if transparency painting has changed in 1.6.0_10. Prior to that I believe transparency can only be achieved in lightweight components (ie. Swing does all the painting). JFrame, JWindow and JDialog are not lightweight because they use OS components.

In the case of a popup, it is lightweight when entirely contained within its parent frame. But a lightweight popup can not be painted outside the bounds of the frame so a JWindow (I believe) is used as the popup, which can't be transparent.

SSCCE: Showing translucent JWindow over the top of translucent JFrame

import com.sun.awt.AWTUtilities;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;

public class OpaqueWindowSSCCE {

    private int countdown = 5;

    public static void main(String[] args) {
        new OpaqueWindowSSCCE();
    }

    public OpaqueWindowSSCCE() {
        final JFrame frame = new JFrame("OpaqueWindowSSCCE");
        final JWindow window = new JWindow();

        new Timer(1000, new ActionListener(){

            @Override
            public void actionPerformed(ActionEvent e) {
                if(--countdown == 0){
                    frame.dispose();
                    window.dispose();
                    System.exit(0);
                } else {
                    frame.repaint();
                }
            }

        }).start();

        frame.setContentPane(new JPanel() {

            @Override
            public void paintComponent(Graphics paramGraphics) {
                super.paintComponent(paramGraphics);
                Graphics2D g = (Graphics2D) paramGraphics.create();
                g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
                g.setColor(new Color(50, 50, 50));
                g.fillRoundRect(0, 0, getWidth(), getHeight(), 10, 10);
                g.setColor(new Color(180, 180, 180));
                g.drawString("Closing in " + countdown + " seconds", 20, 25);
            }
        });

        window.setContentPane(new JPanel() {

            @Override
            public void paintComponent(Graphics paramGraphics) {
                super.paintComponent(paramGraphics);
                Graphics2D g = (Graphics2D) paramGraphics.create();
                g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
                g.setColor(new Color(180, 180, 180));
                g.fillRoundRect(0, 0, getWidth(), getHeight(), 10, 10);
            }
        });

        frame.setUndecorated(true);

        ((JComponent) frame.getContentPane()).setOpaque(false);
        ((JComponent) window.getContentPane()).setOpaque(false);

        AWTUtilities.setWindowOpaque(frame, false);
        AWTUtilities.setWindowOpaque(window, false);

        window.setAlwaysOnTop(true);

        frame.setBounds(200,200,500,500);
        window.setBounds(600,600,200,200);
        frame.setVisible(true);
        window.setVisible(true);
    }
}

回答1:

Try this code part, I had used JWindow though

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class WindowExample
{
    private JWindow window;
    private JLabel updateLabel;
    private int count = 5;
    private Timer timer;
    private int x;
    private int y;
    private ActionListener timerAction = new ActionListener()
    {
        public void actionPerformed(ActionEvent ae)
        {
            updateLabel.setText("Closing Window in " + count + " seconds...");
            count--;
            if (count == 0)
            {
                timer.stop();
                window.setVisible(false);
                window.dispose();
            }   
        }
    };

    private void createAndDisplayGUI()
    {
        final JFrame frame = new JFrame("Window Example");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        frame.setUndecorated(true);
        frame.setOpacity(0.5f);
        frame.addMouseListener(new MouseAdapter()
        {
            public void mouseClicked(MouseEvent me)
            {
                x = me.getX();
                y = me.getY();
                window = new JWindow();
                JPanel contentPane = new JPanel();
                JLabel positionLabel = new JLabel(
                    "X : " + me.getX() + " Y : " + me.getY());
                updateLabel = new JLabel("TImer");  
                contentPane.setLayout(new BorderLayout(5, 5));
                contentPane.add(updateLabel, BorderLayout.CENTER);
                contentPane.add(positionLabel, BorderLayout.PAGE_END);
                window.setContentPane(contentPane);
                window.setOpacity(0.5f);
                window.setSize(200, 100);
                window.setLocation(x + window.getWidth(), y + window.getHeight());
                window.setVisible(true);
                count = 5;
                timer = new Timer(1000, timerAction);
                timer.start();
            }
        });

        frame.setSize(500, 500);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    public static void main(String... args)
    {
        SwingUtilities.invokeLater(new Runnable()
        {
            public void run()
            {
                new WindowExample().createAndDisplayGUI();
            }
        });
    }
}

And here is the output :

WARNING I AM GETTING

C:\Mine\JAVA\J2SE>javac -d classes src\OpaqueWindowSSCCE.java
src\OpaqueWindowSSCCE.java:1: warning: AWTUtilities is internal proprietary API and may be removed i
n a future release
import com.sun.awt.AWTUtilities;
                  ^
src\OpaqueWindowSSCCE.java:68: warning: AWTUtilities is internal proprietary API and may be removed
in a future release
        AWTUtilities.setWindowOpaque(frame, false);
        ^
src\OpaqueWindowSSCCE.java:69: warning: AWTUtilities is internal proprietary API and may be removed
in a future release
        AWTUtilities.setWindowOpaque(window, false);
        ^
3 warnings

来源：https://stackoverflow.com/questions/10527815/translucent-jpopupmenu-inside-a-translucent-window-alternative