The vast majority of plugins are only interested in a single or a few
devices. Require that they enable the frame callback for those devices
and don't notify them for any other frames.
Give each plugin a unique index and use that for a bitmask to check if
the plugin wants events for a particular device. If not, skip it.
Part-of: <https://gitlab.freedesktop.org/libinput/libinput/-/merge_requests/1229>
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 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>
