AWT and Swing windows get opacity options other than 1.0 and 0.0

Befitting the title, Josh Marinacci had a very hacky approach to providing transparent/shaped windows in our book Swing Hacks. Basically, what he did was to use the AWT Robot class to snap a picture of the screen right before showing the window, calculate the portion of the screen overlaid by the soon-to-appear window, and then use those pixels as the background of the window, for the parts that were to appear transparent. This served to make parts of the window transparent, which can also be used to provide shaped windows (in which case the transparent pixels are just around the corners and edges of the window, which itself is still rectangular).

As you might imagine, this was more a cute trick than a practical approach. We did say it was a "hacks" book after all.

But now, we're getting the real deal, as reported in a blog by Kirill Grouchnikov, Translucent and shaped windows in core Java. His blog shows off some screenshots of the various effects supported by build 12 of JDK 6.0u10, and links to his personal blog to describe the code required to achieve these effects.

So, you might be asking, is this just eye-candy, something that lets developers get cute with their GUIs? Well, the test of that will be in how it's put to use, but it's worth noting that these techniques will allow AWT and Swing apps to provide the "HUD Window" that has become all the rage in Mac OS X apps. Like this:

Blogger Austin Heller describes them as "those semi-transparent black windows you see occasionally in applications," and goes on to say:

Over the past couple of years, they've been showing up as pleasant-looking replacements for palettes, and, when implemented properly, can be useful when you have a lot of data to manage -- after all, it's a lot easier to see through a semi-transparent window than a totally opaque one.

They must be pretty intuitive, because while I keep bringing up the opaque DVD controls on the Mac with the ESC key, my five year old son has figured out that just swooping the mouse over the movie brings up a translucent, self-dismissing HUD with basic playback controls (like the QuickTime Player image above), and mousing to the top of the screen brings up a HUD of illustrated chapter stops, something completely unavailable to my old-fashioned, opaque GUI widget. I'm so 2002.

Translucent and shaped windows used to be the vain playground of WinAmp skins, but it turns out they can be quite useful. And now they're available to AWT and Swing. This should be fun...