I want my JLayeredPane to catch all events

Question

I have a JFrame and I want to set it disabled on some loading processes. For that purpose I've created the DisablingLayeredPane class:

public class DisablingLayeredPane extends JPanel {

    @Override
    protected void paintComponent(Graphics g) {
        Graphics2D g2d = (Graphics2D) g.create();
        g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.2f));
        g2d.setColor(Color.BLACK); // With 0.2f alpha it looks like light gray
        g2d.fillRect(0, 0, getWidth(), getHeight());
        g2d.dispose();
    }
}

On the loading process start, I call

frame.getLayeredPane().add(darkeningPane, JLayeredPane.MODAL_LAYER);

But the problem is, this darkening pane does not catch any events, I still can press buttons on my frame. I've also tried AWTEventListener to consume all of events for this frame, but there is another issue: sometimes I need to show modal dialog for some confirmation, and events for modal dialog are consumed too (I can't press any button). Of course, I can use some tricks like using transparent window above my frame instead darkening pane, or use a lot of if-else statements at AWTEventListener, but I'm looking for a some beautiful solution, if any.

Thanks in advance.

UPD: I've also tried to add Mouse and Key Listeners to layered panel, but there is a new issue: if use JDialog instead JFrame, the KeyListener of layered panel would not catch ESC key pressing and dialog would dispose.

UPD2: I've tried frame.setGlassPane(darkeningPane) instead setting as layer, but there is no effect.

Answer 1

It is impossible to intercept events by adding a simple component as a layer in terms of JLayeredPane. It seems that a lot of developers are not aware of this. Events are usually dispatched directly to the deepest child component containing the coordinates of a mouse event or to the focused component in case of a key event ignoring the parents, not to speak layers that are not even parents of the target component.

Thankfully there was a component added in Java 7 which does the complicated trick for you, JLayer, not to confuse with JLayeredPane.

Here is an example of how to use it:

JFrame f=new JFrame("Disabling via JLayer");
final JLayer<JTree> layer = new JLayer<JTree>(new JTree(), new LayerUI<JTree>() {
  @Override
  public void eventDispatched(AWTEvent e, JLayer<? extends JTree> l) {
    if(e instanceof InputEvent) ((InputEvent)e).consume();
  }
  @Override
  public void paint(Graphics g, JComponent c) {
    super.paint(g, c);
    Graphics2D g2d = (Graphics2D) g.create();
    g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.2f));
    g2d.setColor(Color.BLACK);
    g2d.fillRect(0, 0, c.getWidth(), c.getHeight());
    g2d.dispose();
  }
});
f.setContentPane(layer);
layer.setLayerEventMask(~0);
f.pack();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);