This protocol involves far too much accidental complexity. The original
motivating use-case was to provide a convenient way to send arbitrary
data to layout clients at runtime in order to avoid layout clients
needing to implement their own IPC and do this over a side-channel.
Instead of implementing a quite complex but still rigid options protocol
and storing this state in the compositor, instead we will simply add
events to the layout protocol to support this use case.
Consider the status quo event sequence:
1. send get_option_handle request (riverctl)
2. roundtrip waiting for first event (riverctl)
3. send set_foo_value request (riverctl)
4. receive set_foo_value request (river)
5. send foo_value event to all current handles (river)
6. receive foo_value event (rivertile)
7. send parameters_changed request (rivertile)
8. receive parameters_changed request (river)
9. send layout_demand (river)
And compare with the event sequence after the proposed change:
1. send set_foo_value request (riverctl)
2. receive set_foo_value request (river)
3. send set_foo_value event (river)
4. send layout_demand (river)
This requires *much* less back and forth between the server and clients
and is clearly much simpler.
Options are now all global but may be overridden per-output. If an
output local value is requested but none has been set, the global value
is provided instead. This makes for much better ergonomics when
configuring layout related options in particular.
Replace the current layout mechanism based on passing args to a child
process and parsing it's stdout with a new wayland protocol. This much
more robust and allows for more featureful layout generators.
Co-authored-by: Isaac Freund <ifreund@ifreund.xyz>
This allows the compositor to restrict options to a certain set of
values, which can be desirable if the options affect compositor
behavior.
This was always the intended behavior of the protocol, but now it is
explicitly stated.
Add an output arg to the success event on the callback. This allows for
implementing commands that return values, which are planned.
Replace the array of null terminated strings with a series of requests
each adding a single string to the args array. This is more idiomatic
wayland.
Add a seat argument to the run_command request to allow for proper
multi-seat support in the future.
Add missing destructor request.
