When a device is removed from the seat the events that this device may have
emitted just before being removed might still be in the stage events queue,
this may lead a to a crash because:
Once the device is removed, we dispose it and the staling event is
kept in queue and sent for processing at next loop.
During event processing we ask the backend to update the last device
with the disposed device
The device is disposed once the events referencing it, are free'd
The actual last device emission happens in an idle, but at this point
the device may have been free'd, and in any case will be still disposed
and so not providing useful informations.
To avoid this, once a device has been added/removed from the seat, we queue
ClutterDeviceEvent events to inform the stack that the device state has
changed, preserving the order with the other actual generated device events.
In this way it can't happen that we emit another event before that the
device has been added or after that it has been removed.
Fixes: https://gitlab.gnome.org/GNOME/mutter/-/issues/1345
Add a method to ClutterSeat that allows peeking the list of input
devices and allow looping through devices a bit faster. The API left is
private so we can make use of peeking the GList internally, but don't
have to expose any details to the outside, which means we'd have to
eventually stick with a GList forever to avoid breaking API.
Since we now have the peek_devices() API internally, we can implement
ClutterSeats public list_devices() API using g_list_copy() on the list
returned by peek_devices().
https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1275
On x11 we emulate pointer events from touch events as long as there's
only one touchpoint on screen, this obviously leads to x11 sending us
crossing events triggered by the emulated pointer. Now if we get a leave
event and set the stage of the ClutterInputDevice to NULL, new touch
events will be discarded by clutters backend because the core pointer
doesn't have a stage associated. This means Mutter completely loses
state of a touchpoint as soon as it crosses a shell actor.
An easy reproducer for this issue is to start the four-finger-workspace
gesture above a window and to move the pointer emulating touch outside
of the window, this will freeze the gesture as the gesture no longer
receives touch events.
To fix this, stop tracking stage changes on crossing events and simply
leave the ClutterInputDevice stage as-is. In our case there is only one
stage anyway and that won't change in the future.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/423
The devices_by_id hash table is responsible for managing the reference
to the devices. In remove_device however, for non-core devices there are
additional calls to dispose/unref, after the last reference has
already been dropped by the hash table.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/1032
