Add support for an artificial UNINITIALIZED marking for ClutterActorBox,
done by setting the boxes origin to Infinity and its size to -Infinity.
That is a value that's considered an invalid allocation by Clutter and
which can never be set by sane code.
This will allow setting the allocation of ClutterActors to an
UNINITIALIZED box when creating actors or when removing them from the
scenegraph and makes it possible to explicitely detect uninitialized
allocations, which is useful in a few cases.
https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1290
`ClutterOffscreenEffect` had been getting the wrong bounding box in the
case of clones and descendents of clones, causing visibly incorrect
clipping. This was due to `clutter_actor_get_paint_box` only ever being
given the source actor during a paint (which is correct) and not the clone.
Even if we weren't painting a clone but an offscreened descendent of a
clone (like in gnome-shell's desktop zoom), we would get the wrong result.
Fortunately we don't need to know the actual clone/actor being painted so
don't need to call the problematic `clutter_actor_get_paint_box` at all.
The solution is to only keep untransformed rendering in the FBO and leave
the correct transformation for later. The correct clone/actor's
transformation is already set for us as the current cogl modelview matrix
by `clutter_actor_paint`.
Bonus optimization: This all means we don't need to keep `last_matrix_drawn`
or force a full repaint every time some part of the transformation changes.
Because the FBO contents are no longer affected by transformations. As it
should be. In other words, offscreen-effected actors can now move around
on screen without themselves being repainted.
Special thanks to Mai Lavelle for identifying the cause of the problem.
Fixes:
https://bugzilla.gnome.org/show_bug.cgi?id=789050,
https://bugzilla.gnome.org/show_bug.cgi?id=659523#c9,
https://gitlab.gnome.org/GNOME/mutter/issues/196,
https://gitlab.gnome.org/GNOME/mutter/issues/282,
https://gitlab.gnome.org/GNOME/gnome-shell/issues/387,
https://launchpad.net/bugs/1767648,
https://launchpad.net/bugs/1779615
In cogl use cogl-config.h and in clutter use clutter-build-config.h. We
can't use clutter-config.h in clutter because its already used and
installed.
https://bugzilla.gnome.org/show_bug.cgi?id=768976
