Create a rounded JFrame / ContentPane

Question

I'm creating a login window with rounded corners in java. Everything is OK, see pic, but i'm having challenges making the JFrame / ContentPane transparent. There are white areas at each corner (shown by the arrows) that i seem not to be able to remove since i can't set opague to false for the JFrame or ContentPane.

Any ideas of how i can remove these white areas

Answer 1

Since Java 1.3 there's a trick which allows to make partially transparent windows, or windows fading in (I usually use this for my splash screens), or special FX (such as shadows):

• Before opening the window, programmatically take a screenshot of the region where your window is going to be (using java.awt.Robot.createScreenCapture())
• Set the screenshot as the background of your root container (JPanel with custom paintComponent() routine)
• Now you can add all kinds of transparent components, or paint another semitransparent image on top of the background.

Example which creates a window with a semitransparent shadow using this technique: http://www.eclipsezone.com/eclipse/forums/t17720.html