Swing Hacks

Make Your Frame Dissolve #42

Chapter 6, Transparent and Animated Windows

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HACK

H A C K

#42

Make Your Frame Dissolve Hack #42

Create animated frame dissolves using two screenshots and some clever

graphics code.

Dissolve is a term from old motion pictures where the director would switch

scenes by fading, or dissolving, from one image to another. Eventually direc-

tors came up with more interesting dissolves like the vertical wipe, the vene-

tian effect (little thin strips that look like venetian blinds), and the classic

fade to black. With a little bit of screenshot hackery, you can create similar

effects in Swing, allowing your program to fade away or do some other inter-

esting animation when the user quits.

AWT doesn’t support real transparent or shaped windows (though you can

fake it with a screenshot pasted into a window that fills the screen

[Hack #41].

Most dissolves involve applying some graphic effect to both the starting and

ending images, which in this case means the application window itself and

the rest of the user’s desktop under the window. With this in mind, the

basic plan is four steps:

1. Capture an image of the window.

2. Capture an image of the entire screen without the window.

3. Cover up the entire screen with a new window.

4. Show the dissolve animation.

Figure 6-3. Running the MP3 player