how to correctly override input transforms (for rotating touch screens) with hyprctl

[ppenguin]

I made a small HM (nixos) module with a user service to apply a display transform based on device attitude (via iio-sensor-proxy). However, I (obviously) need to also rotate the screen's digitizer (touch panel and stylus) via libinput.

I couldn't make it work from the info on the wiki, plagued by the following issues:

I can't seem to correctly match the device name:

hyprctl devices

...
Tablets:
        Tablet at 14831b0:
                elan2514:00-04f3:29f5-stylus


Touch:
        Touch Device at 14a32e0:
                elan2514:00-04f3:29f5
...

If I declare in the config

device:elan2514:00-04f3:29f5 = {}
# or, no idea how "less specific name matches actually work? Documentation???
device:elan2514 = {}

I get errors saying No such field for that device for options I have defined globally in the input section.
Not a big issue, but I still want to apply some options to all mice-like devices, like e.g. natural scrolling and follow focus.

Temporarily disabling all such "global input" options gets rid of the error.

But I'm still not able to call this

> hyprctl keyword device:elan2514 'transform,2'
Error setting value <transform,2> for field <device:elan2514>: No such field.

(or any variation of it, including variations with the device name all lowercase and : and <space> replaced by -).

If I do something like

> hyprctl keyword device:elan2514:transform '2'
ok

it gives ok, but doesn't have any effect.

It also seems to matter where in the config I define input and device blocks: if I do this "too high" I get additional errors that general options are not available for the declared device.

So the questions:

1. How to declare my touch screen and stylus correctly in the config (ref. http://wiki.hyprland.org/Configuring/Keywords/#per-device-input-configs)?
2. How does device name matching actually work? (So I can leverage the name matching to define the same attributes for a certain class of input devices (e.g. all touch/tablet, or all mice)
3. how to call hyperctl correctly with the target device and a transform (as stated, my tests acc. to the things gleaned from the wiki were unsucessful)
4. related to (2): since I needed to remove the generic input options follow_mouse, accel_profile, sensitivity (which I assume should apply to all pointer devices?) to avoid errors, where to re-add them "semi-generically" (i.e. for all pointer-devices or for all mice + touchpads) and similarly for natural_scroll.

Note that the objectives for the config include using the same config on multiple machines, i.e. defining multiple devices/device-classes that may or may not be available, since non-existing devices will be safely ignored anyway. Apart from the above issues this seems to work as expected.

[vaxerski]

device:your-dev-name {
    opt = var
}

name matching matches the name not a class. your name is wrong, you input elan2514 while the name given by hyprctl is clearly elan2514:00-04f3:29f5
You can't match a class, for that, the global rules inside input can be used

hyprctl keyword device:elan2514:00-04f3:29f5:your_opt value

why would you need to remove them? they will be replaced wherever overriden and use the global otherwise.

[ppenguin]

@vaxerski Thanks a lot for your quick reply!

Ah, actually the "category declaration" (as I understood it from the wiki I had to include this in the config before I could refer to it from hyprctl) didn't appear to be necessary, i.e. I could directly run:

hyprctl keyword device:elan2514:00-04f3:29f5:transform '2'

My second mistake was that I implicitly understood from the tip here that I also had to replace : by -, since otherwise the keyword argument would seem ambiguous (splitting character for keywords in the name). But it indeed works with the verbatim device name.

There's one remaining issue though:

• While the transform works for the touch-screen (hyprctl keyword device:elan2514:00-04f3:29f5:transform '2'), it doesn't work for the stylus (with also the exact device name: hyprctl keyword device:elan2514:00-04f3:29f5-stylus:transform '2'). The latter remains untransformed when I execute the command.

Any ideas?

[vaxerski]

https://wiki.hyprland.org/Configuring/Keywords/#per-device-input-configs

styluses / pens / drawing tablets' transforms are not supported in hyprland, only touchscreens for now.

[ppenguin]

Thanks, ah, too bad, guess I'll try my luck with libinput cli or some such (maybe I can pass the transformation matrix dynamically?).

When I find some time I might check out a bit more how hyprland uses libinput, hopefully to contribute, I guess it basically wraps it to translate configuration calls to the lib?
I'll also consider making some PRs to the wiki, so you don't have to suffer too many "unnecessary" questions 😉

[ppenguin]

This is now being worked on in #1319