[SOLVED] GTK: Window transparency

[tuxor]

Look at the following screenshot:

Left: OSD from gnome-settings-daemon (http://git.gnome.org/browse/gnome-se...d-osd-window.c), coded in C with Cairo and GTK
Right: I coded this one in Python with PyCairo and PyGtk

The transparent black rounded rectangles have the same color. They appear to be the same when looked at on white background. But they differ significantly on the black background.

How did the gnome-programmers achieve, that their "leve of transparency" adapts to the background?

[Gareth Jones]

My guess would be, instead of e.g. 50% transparent black, maybe e.g. 75% transparent dark grey, so that on white the overall effect is the same level of darkening, but on black the tendency is to lighten.

Gareth

[tuxor]

Originally Posted by Gareth Jones

My guess would be, instead of e.g. 50% transparent black, maybe e.g. 75% transparent dark grey, so that on white the overall effect is the same level of darkening, but on black the tendency is to lighten.

Gareth

Thanks, I don't know, why I didn't think of this myself. Of course, the trick is: 75% alpha + 7% grey, instead of 70% alpha and 0% grey (i.e. black).