Add protocol for sub-surfaces, wl_subcompositor as the global interface,
and wl_subsurface as the per-surface interface extension.
This patch is meant to be reverted, once sub-surfaces are moved into
Wayland core.
Changes in v2:
- Rewrite wl_subcompositor.get_subsurface description, and move mapping
and commit details into wl_subsurface description. Check the wording
in wl_subsurface.set_position description.
- Add wl_subsurface.set_commit_mode request, and document it, with the
commit_mode enum. Add bad_value error code for wl_subsurface.
- Moved the protocol into Weston repository so we can land it upstream
sooner for public exposure. It is to be moved into Wayland core later.
- Add destroy requests to both wl_subcompositor and wl_subsurface, and
document them. Experience has showed, that interfaces should always
have a destructor unless there is a good and future-proof reason to not
have it.
Changes in v3:
- Specify, that wl_subsurface will become inert, if the corresponding
wl_surface is destroyed, instead of requiring a certain destruction
order.
- Replaced wl_subsurface.set_commit_mode with wl_subsurface.set_sync and
wl_subsurface.set_desync. Parent-cached commit mode is now called
synchronized, and independent mode is desynchronized. Removed
commit_mode enum, and bad_value error.
- Added support for nested sub-surfaces.
Signed-off-by: Pekka Paalanen <ppaalanen@gmail.com>