[cairo] [PATCH 0/2] Fixes for cairo-gl gradients

[Andrea Canciani]

Cairo-gl is still drawing "old" radial gradients (not the PDF-like
ones) and I'd like it to be fixed before 1.11.0. I implemented them
using the same definition as in pixman, but to avoid branches I had to
restructure the computations in three different shaders.

The new code (and radial-gradient-mask-source) made an existing bug,
which was causing a failure in the mask test, much more visible.
A fix for it is provided in the second patch.

The code has been tested both on Mesa swx and on real hardware and
should not touch any critical part of the gl backend (I'm not changing
lock-related things), but it is basically my first attempt at gl
coding, so it is quite possible that I have assumed something false or
done something wrong.

Testing/reviews/comments are appreciated

Andrea

PS: This evening I pushed 29439bd7724031504e965ffe5b366baaeeae07d8 to
pixman/master, which should fix radial gradients for image, xlib and
xcb.