Most backends relies on gettimeofday(2) for output repaint timestamps
but this is not a requirement. Before this patch repaints coming from
idle_repaint() always used gettimeofday(2) for timestamps. For backends
not using that time source this could cause large jumps between
timestamps.
To fix this, timestamps needs to always come from the backend. This
means that the backend needs to always be responsible of starting the
repaint loop in case that the repaint cannot start immediately.
The drm backend implementation is from the patch by Ander Conselvan de
Oliveira found here:
http://lists.freedesktop.org/archives/wayland-devel/2013-February/007393.html
Signed-off-by: Jonas Ådahl <jadahl@gmail.com>
Backends may move surfaces to different planes, in which case damage is
generated in the primary plane. This damage is usually passed to the
renderer, but in some cases the backend may decide to not render
anything (that's the case when drm compositor scans out a client
buffer). In that case the damage on the primary plane would be
discarded, leading to artifacts later.
This patch makes the backend's responsibility to clear the damage on
the primary plane, so that unrendered damage is kept for as long as
necessary.
Add a headless backend and a noop renderer, mainly for testing
purposes. Although no rendering is performed with this backend,
this allow some of the code paths inside Weston and shm clients
to be tested without any windowing system or any need for drm
access.
Jonas Ådahl
Kristian Høgsberg
Vasily Khoruzhick
Ander Conselvan de Oliveira