This uses MetaCompositorViewNative to find a candidate surface for
scanout and to keep track of it separately for each view, effectively
allowing each CRTC to use a different buffer for direct scanout.
There are three parts for potentially assigning a buffer for direct
scanout at the compositor level:
1. Finding a candidate surface actor on the view (if any)
2. Attempting to assign the candidate's buffer for direct scanout
3. Updating references relating to the scanout candidate as needed
The three parts were moved in their entirety from being handled by the
MetaCompositorNative to being handled by the MetaCompositorViewNative.
As part of this transition, the logic was also slightly refactored so
that each of the three parts is handled by its own helper function.
This allowed to avoid the use of "goto" statements and hopefully make
the logic easier to read and follow.
The first part mentioned above was changed in this commit to make use
of the new meta_compositor_view_get_top_window_actor () API to get the
top window actor in the view instead of the top window actor on all
views.
The second part and third parts mentioned above weren't changed other
than being done in the context of a view instead of globally.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2526>
This class is meant to hold logic specific to the native backend
in the context of a MetaCompositorView.
Its addition requires making MetaCompositorView inheritable, and an
addition of a virtual function which allows each compositor to create
its own MetaCompositorView instance.
In the case of the MetaCompositorNative, a MetaCompositorViewNative
is created. In all other cases, a MetaCompositorView is created.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2526>
