This API is the one accessed from different bits of the UI thread,
make it "async" (it's basically one-way setters, so API stays the same
in the surface) and able to run in the MetaSeatImpl main context.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
Simplify the handling of numlock state, so it can be entirely handled
within the input thread. Since the saving/restoring is triggered inside
each backend code, there's no need anymore for meta_backend_set_numlock().
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
Push it a little bit down to the MetaSeatNative. As both the UI thread
and the input thread are interested in dealing with the xkb_keymap and
it is not meant to be used in different threads, keep 2 separate copies
around.
The keyboard map will always be set from the UI thread, so the xkb_keymap
owned by the MetaSeatNative (owned by the UI thread) can be considered
canonical.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
Wrap all keyboard state updates, and all pointer/stylus/touch cursor
position with a write lock, and ::query_state() (The only entrypoint
to this state from other threads) with a read lock.
The principle is that query_state may be called from different threads
(UI so far, but maybe KMS too in the future), while the input thread
may (or may not) be updating it. This state is fetched "atomically"
(eg. x/y will be consistently old or new, if the input thread were
updating it at the same time).
There's other places deep in backends/native that read this state,
they all will run in the input thread, so they count as "other readers"
to the other thread. Those changes are already mutually exclusive with
updates, so they don't explicitly need the RW lock.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
These changes will happen in the input event management code, so let them
be emitted via the MetaSeatImpl, as that's what we'll have neat access to.
The ClutterSeat signals are now emitted from there.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
Move most of the functional bits (those meant to run on a standalone
thread) to a MetaSeatImpl object. This object is managed by the MetaSeatImpl
and not exposed outside the friend MetaSeatNative/MetaInputDeviceNative/
MetaInputSettings classes.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
