Up to now, we always asked the X11 server for color allocation ("which
pixel value corresponds to (r,g,b)?", an AllocCollor request).
This commit adds direct support for TrueColor and DirectColor visuals.
In such a visual, the X11 server gives tells us where the red, green,
and blue color components are in a pixel value and we can then just
directly compute the pixel value.
Additionally, this commit adds code that assumes that in a depth=32
visual, the remaining values (after handling red, green, blue) is the
alpha channel for colors. Thus, this adds support for transparent client
borders.
This commit also touches code for the systray. However, the systray must
always use the X11 server's default visual and that one always(?) has
depth=24, i.e. does not support an alpha channel. Thus, the systray
background still cannot be transparent.
Also, in theory this commit should support visuals where some color
component does not have 8 bits, for example RGB565. However, this is
just theoretic and I have no idea how to actually test this (without
jumping through too many hoops).
Fixes: https://github.com/awesomeWM/awesome/issues/162
Signed-off-by: Uli Schlachter <psychon@znc.in>
1acae2aa6c