tree 22a3f0e0a20878bd9c7ee35b616655632824c646
parent ddaf95c5a1f0caa88a7c9348ef7af9fd07d1e8d6
author Daniel Stone <daniels@collabora.com> 1531219465 +0100
committer Daniel Stone <daniels@collabora.com> 1531308295 +0100

compositor-drm: Disallow overlapping overlay planes

The scanout plane strictly stacks under all overlay planes, and the
cursor plane above. However, the stacking of overlay planes with respect
to each other is undefined.

We can control the stacking order of overlay planes with the zpos
property, though this significantly complicates plane assignment. In the
meantime, simply disallow assigning a view to an overlay, when it
overlaps another view which is already on an overlay. This ensures
stacking order is irrelevant, since the planes never intersect each
other.

Signed-off-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>