This allows MetaCullable to work with actors using arbitrary transforms
which will be needed for implementing surface pixel alignment for
fractional-scale-v1.
This also deletes meta_cullable_is_untransformed as it's no longer
necessary, and we can also stop manually scaling the region objects
while performing opaque region culling in surfaces since it's now
handled transparently by the new `meta_cullable_cull_out_children`
implementation.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2726>
Some cullable implementation may have extra information about their
expected size. The main example here are surface actors which can be scaled
by geometry scale.
Add an API to overwrite the default size / untransformed check for such cases.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/1036
The order and way include macros were structured was chaotic, with no
real common thread between files. Try to tidy up the mess with some
common scheme, to make things look less messy.
Instead of hardcoded knowledge of certain classes in MetaWindowGroup,
create a generic interface that all actors can implement to get parts of
their regions culled out during redraw, without needing any special
knowledge of how to handle a specific actor.
The names now are a bit suspect. MetaBackgroundGroup is a simple
MetaCullable that knows how to cull children, and MetaWindowGroup is the
"toplevel" cullable that computes the initial two regions. A future
cleanup here could be to merge MetaWindowGroup / MetaBackgroundGroup so
that we only have a generic MetaSimpleCullable, and move the "toplevel"
cullability to be a MetaCullableToplevel.
https://bugzilla.gnome.org/show_bug.cgi?id=714706
