JFrame semi-transparent / transparent for events but still visible

Is it possible to create in Java JFrame

or another component completely transparent to all mouse events?

In my application, I only have one window, which is an instance JFrame

. I have many others JComponent

in this window , some of them have more JComponent

, etc. But most importantly, the main window has only one PopUpFrame

, which inherits JFrame

. This one is PopUpFrame

invisible until I move the cursor to a specific one JComponent

with a thumbnail, when this one JComponent

catches an event mouseEntered(MouseEvent event)

, it will make this one PopUpFrame

visible and load the full image into it. I did that PopUpFrame

move with the cursor, but the problem is that the cursor goes out of the sketch PopUpFrame

. For example, ifPopUpFrame

with full image is the right side of the cursor and I move the mouse to the left and / or up, everything works fine. When I move the mouse to the right and / or down, the cursor continues PopUpFrame

, so it is PopUpFrame

"frozen". Of course I can add one additional event to this PopUpFrame

and it will move with the cursor even when the cursor is on it, but this is not a solution. PopUpFrame

should be visible ONLY when the cursor is on the thumbnail. If PopUpFrame

can capture events and thumbnail covers, I cannot catch mouseExited(MouseEvent event)

in the correct thumbnail value.

So, somehow make the JFrame completely transparent to mouse events, but still make it visible on the screen (probably something like that setMouseTransparent

in JavaFX). And if that is not possible, then how to create a full image (and only image) popup that is visible only when the cursor is on the thumbnail and is moved with the cursor.

Here is my code.

import java.awt.Color;
import java.awt.Point;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;
import javax.swing.ImageIcon;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

public class MainExample {

    private static MainWindow window;

    public static void main(String args[]) {
        window=new MainWindow();
    }
}

class MainWindow extends JFrame {

    private static PopUpFrame popup=new PopUpFrame();
    private static ThumbnailPanel mini=new ThumbnailPanel("panel");

    public MainWindow() {
        setVisible(true);
        setSize(600, 400);
        setLayout(null);

        add(mini);
        mini.setLocation(50, 75);
    }

    public static void previewPopUpShow(Point cursor) {
        popup.refresh(cursor.x, cursor.y);
    }

    public static void previewPopUpHide() {
        popup.setVisible(false);
    }

    public static void previewPopUpLoad(String url) {
        popup.setImage(url);
    }
}

class ThumbnailPanel extends JComponent {

    private JPanel thumbnail=new JPanel();

    public ThumbnailPanel(String name) {
        setVisible(true);
        setOpaque(false);
        setSize(80, 45);
        setBorder(null);
        setLayout(null);

        add(thumbnail);

        thumbnail.setBackground(Color.RED);
        thumbnail.setBorder(null);
        thumbnail.setBounds(0, 0, 70, 40);
        thumbnail.addMouseListener(new MouseAdapter() {
            public void mouseEntered(MouseEvent entered) {
                MainWindow.previewPopUpLoad("");
            }

            public void mouseExited(MouseEvent exited) {
                MainWindow.previewPopUpHide();
            }
        });
        thumbnail.addMouseMotionListener(new MouseMotionAdapter() {
            public void mouseMoved(MouseEvent moved) {
                MainWindow.previewPopUpShow(moved.getLocationOnScreen());
            }
        });
    }
}

class PopUpFrame extends JFrame {

    private ImageIcon full;
    private JLabel fullLabel;

    public PopUpFrame() {
        setSize(440, 260);
        setResizable(false);
        setUndecorated(true);
        setVisible(false);
        setFocusable(false);
        setAlwaysOnTop(true);

        addMouseMotionListener(new MouseMotionAdapter() {
            public void mouseMoved(MouseEvent moved) {
                MainWindow.previewPopUpShow(moved.getLocationOnScreen());
            }
        });
    }

    void refresh(int x, int y) {
        setLocation(x, y);
    }

    void setImage(String url) {
        full=new ImageIcon("full_image.png");
        fullLabel=new JLabel();
        fullLabel.setOpaque(true);
        fullLabel.setBackground(Color.WHITE);
        this.getContentPane().add(fullLabel);
        this.setVisible(true);
    }
}