Transparent windows on Linux

JavaFX makes it easy to create non-rectangular windows -- just set a StageStyle.TRANSPARENT on your stage.style. We use rounded corners on our popup menus, and we also have a non-rectangular and alpha-blended splash screen. The other day I was checking how the cursors were looking on different platforms, and imagine my horror when I discovered how our new splash screen and rounded menus looked on Linux! Here they are -- as you can see you end up with white rectangles around the supposed-to-be-blended areas: That looks.... craptastic! Historically, the JDK didn't support alpha blended windows on Linux. However, that was added a while ago (I'm not sure exactly which version, but I think it was JDK 6 update 14). It turns out that the FX code which initializes the native frame for the stage does not do conditional checking for this; it simply turns off transparency on Linux. Fortunately, there's a System property you can set to force it to respect the transparency flag. You would obviously only do this if you know you are running on a JDK which supports transparency. And that's easy! In your startup code, do something like this: if (Utils.IS_LINUX and Utils.jdkAtLeast(1, 6, 0, 14)) { java.lang.System.setProperty("javafx.allowTransparentStage", "true"); } There are a couple of utility methods here that are simple - just looking at some system properties to determine whether we're on Linux and whether we're o...

Date: March, 25 2010
Url: http://blogs.sun.com/tor/entry/transparent_windows_on_linux

Others News