java怎么让窗口覆盖窗口,如何在Java中创建覆盖窗口？

I'm trying to create a HUD style display for a foreign application.

To do this, I'd need to make a transparent overlay window, that would be placed on top

of the window of the foreign application. The overlay window should allow me to place

widgets and draw text on it. Events should get forwarded to the underlying window,

if they happen on the transparent area (and otherwise allow the widgets to work as

expected).

I'm doing this on OSX with Java. I'd hope to do this with pure Java with portability to

other platforms, but if not possible, I'd be fine with solutions that would just allow

me to do this on OSX through Cocoa (Rococoa) or Carbon.

解决方案

Actually, was able to figure this out myself. Seems to be easier than I expected:

public class Overlay {

public static void main(String[] args) {

JFrame frame = new JFrame("Transparent Window");

frame.setUndecorated(true);

frame.setBackground(new Color(0, 0, 0, 0));

frame.setAlwaysOnTop(true);

// Without this, the window is draggable from any non transparent

// point, including points inside textboxes.

frame.getRootPane().putClientProperty("apple.awt.draggableWindowBackground", false);

frame.getContentPane().setLayout(new java.awt.BorderLayout());

frame.getContentPane().add(new JTextField("text field north"), java.awt.BorderLayout.NORTH);

frame.getContentPane().add(new JTextField("text field south"), java.awt.BorderLayout.SOUTH);

frame.setVisible(true);

frame.pack();

}

}