Use cosmic-config for input config; changeable at runtime

[ids1024]

With this, it's possible to change xkb-config and input-devices and immediately see them effect the compositor.

In an earlier draft for input configuration I had a method:

pub fn register_handler<T: serde::de::DeserializeOwned + 'static>(
    &mut self,
    name: &'static str,
    cb: fn(T, &mut State),
)

But I'm not sure that makes the code less entangled without more changes.

pop-os/libcosmic#126 would make a few things cleaner, but I'm still not sure on that design.

Leaving as a draft until cosmic-settings is updated to make use of this. And input-devices may not be the best way to configure input, but we'll need to think about the design there.

After input settings, settings from config.ron can also be migrated to cosmic-config and made changeable at runtime. outputs.ron can be dealt with later since we already have dynamic persistent output configuration that more or less works with wdisplays.

[Drakulix]

Looks good to me code-wise.

But I'm not sure that makes the code less entangled without more changes.

Me neither, seems clean enough to me anyway.

And input-devices may not be the best way to configure input, but we'll need to think about the design there.

I think this is the biggest issue here. Looking at the cosmic-settings design, we need a way to configure defaults for a device type. I would like to retain the ability to special case the configuration of specific devices, though updating the defaults should probably also update all known devices, otherwise cosmic-settings UI wouldn't work as expected.

Thinking about this we might want to make a HashMap<DeviceCapability, InputConfig>?

outputs.ron can be dealt with later since we already have dynamic persistent output configuration that more or less works with wdisplays.

Though this depends on the wlr-output-configuration protocol, which doesn't necessarily expose everything we want to make configurable in the long term. E.g. it only recently added variable refresh rate, so for cosmic-settings I think we want to use the cosmic-config, while keeping wlr-output-configuration for compatibility with other apps.

[ids1024]

Thinking about this we might want to make a HashMap<DeviceCapability, InputConfig>?

Would that group mouse and touchpad acceleration? I think the designs have those separate, as is commonly done.

[Drakulix]

Right... So maybe we need to match on some property of the UdevDevice to figure out the device "type".

[Drakulix]

So the solution is to just treat touchpads differently from everything else?

[ids1024]

Yes. It's awkward, but I don't see a better way to do it with the current design we have for settings. Unless we want to just have individual settings like touchpad-speed instead of this general mechanism.

We can't really have settings per capability because a device can (in principle) have any number of capabilities. Libinput doesn't have "device types" even if things like Gnome Shell try to act like it does. I guess settings are largely tied to a particular capability, looking at libinput I didn't see any explicit association.

[Drakulix]

Just wanted to confirm, I don't think this is a terrible idea and I also don't see any obvious issues, it just seemed.. odd.

What is missing to get this out of "Draft"-status?

[ids1024]

I still need to make use of this for mouse/touchpad settings in cosmic-settings and use that to test that its working as expected, but otherwise this PR should be good. Moving other settings to cosmic-settings can be done after this is merged.

[Drakulix]

I still need to make use of this for mouse/touchpad settings in cosmic-settings and use that to test that its working as expected, but otherwise this PR should be good. Moving other settings to cosmic-settings can be done after this is merged.

Sounds good. Please give me a ping once this is ready for final review and merge. I haven't found any glaring issues with the approach. Quite the opposite, I think this version looks quite clean! :)

[ids1024]

After a couple small changes to cosmic-comp-config, and making it not spew DeviceConfigError::Unsupported trying to set default config for devices that don't support it, (and remembering to delete an old input-devices that was overriding the defaults), this seems to be working and suitable for use in cosmic-settings.

So probably no need to do more on this branch, and we can merge it.