Determine endianess of wl_shm pixel format codes
@pq
Submitted by Pekka Paalanen Assigned to Pekka Paalanen @pq
Description
The main issue was described here:
https://lists.freedesktop.org/archives/wayland-devel/2017-March/033492.html
Cairo supports a single ARGB format, and the definition of that format is native-endian (machine endian). I presume initially the two formats that wl_shm
server implementations are required to support match the ARGB and RGB Cairo formats. Later DRM pixel formats were added to the format list of wl_shm
. Now the question is, do wl_shm
pixel formats follow Cairo (native-endian) or DRM (little-endian)?
If that was not awkward enough, the question has been raised whether the DRM pixel formats are actually used as little-endian or native-endian:
https://lists.freedesktop.org/archives/dri-devel/2017-April/138633.html
Test results from the DRM format thread:
https://lists.freedesktop.org/archives/dri-devel/2017-April/139311.html
https://lists.freedesktop.org/archives/dri-devel/2017-April/139381.html
https://lists.freedesktop.org/archives/dri-devel/2017-April/139403.html (screenshots of GNOME)
https://lists.freedesktop.org/archives/dri-devel/2017-April/139469.html