This makes event handling easier where plugins queue other event frames
per frame. Our initialization guarantees that our evdev code is alway
the last plugin in the series so in the no-plugin case we just pass on
to that.
The effective event flow is now:
evdev.c -> plugin1 -> plugin2 -> evdev-plugin.c -> evdev.c
except that no plugins exist yet.
Part-of: <https://gitlab.freedesktop.org/libinput/libinput/-/merge_requests/1217>
This adds a callback for plugins (and lua plugins) to inject an evdev
frame into the event stream. Unlike the prepend/append functions
this one injects the event at the bottom of the plugin stack as if
the device had sent the frame right then and there.
There's a drawback though: the event frame isn't marked as synthetic
so it cannot be identified without having a guard in the plugin so
the same frame is not reprocessed.
Part-of: <https://gitlab.freedesktop.org/libinput/libinput/-/merge_requests/1217>
This adds a event queue pointer to each plugin that is set when the
plugin's evdev_frame() callback is invoked. If the plugin calls
libinput_plugin_queue_event_frame() during the callback the given
event frame is appended to an event frame list (starting with the
current frame). Once the callback completes, that frame list is
passed to the next plugin and each frame is replayed on the next plugin.
In the case of multiple plugins queueing events this effectively builds
a tree of frames which each level of the tree representing one plugin.
Part-of: <https://gitlab.freedesktop.org/libinput/libinput/-/merge_requests/1217>
This adds the scaffolding for an internal plugin architecture. No such
plugin currently exists and any plugin implemented against this
architecture merely is plugin-like in the event flow, not actually
external to libinput.
The goal of this architecture is to have more segmented processing
of the event stream from devices to modify that stream before libinput
ever sees it. Right now libinput looks at e.g. a tablet packet and then
determines whether the tool was correctly in proximity, etc.
With this architecture we can have a plugin that modifies the event
stream that the tool is *always* correctly in proximity and the tablet
backend itself merely needs to handle the correct case.
The event flow will thus logically change from:
evdev device -> backend dispatch
to
evdev device -> plugin1 -> plugin2 -> backend dispatch
The plugin API is more expansive than we will use immediately, it is the
result of several different implementation branches that all require
different functionality.
Part-of: <https://gitlab.freedesktop.org/libinput/libinput/-/merge_requests/1217>
