gsk: Document blend modes
authorMatthias Clasen <mclasen@redhat.com>
Mon, 18 May 2020 22:21:39 +0000 (18:21 -0400)
committerMatthias Clasen <mclasen@redhat.com>
Mon, 18 May 2020 22:21:39 +0000 (18:21 -0400)
commitec2aac5b61ec5b723cdde6d5976210539cf4e3ed
tree387d86463209f0cac6cfe7b59b21fd4bcfdbf6b9
parent15f7d2a27d6af5ef16781a472547acfb2f9484a2
gsk: Document blend modes

Add some information about blend modes, mostly taken
from the css compositing spec.

Fixes: #2739
gsk/gskenums.h