Why is key press simulation not working for Niri ?

[Zhaith-Izaliel]

Hi! I tried to make sense of the Niri Backend to understand why hotkey press simulation doesn't work but I couldn't figure it out and the reason why is not given in the documentation. Do you happen to know why?

Perhaps you know why @make-42 since you're the person who worked on the MR for the Niri integration?

Thank you for anyone who will take the time to answer my question! ❤️

[yar2000T]

[Zhaith-Izaliel]

My question is not on "if" it works or not for the current implementation, but "why" it doesn't work.

I know it doesn't work for Niri. I want to know why hotkey press simulation doesn't work. What are the technical reason why it can't be achieved. Is the reason related to Smithay ? Niri itself ? Or the current backend used for Niri in Kando ?

I want to know why so I can try to contribute where it's relevant to allow hotkey press simulation for Niri to work.

[make-42]

I'll have a look give me a sec

[make-42]

do all key press simulations not work? or it is just to trigger a shortcut defined in the Niri configuration?

[make-42]

The used protocol is supported by Niri and I believe that in my testing having it type letters worked

[make-42]

I'll do some testing on my end and tell you

[make-42]

Yeah, it works fine for anything that isn't Niri keybinds, at least on my machine. This is documented in Kando's Niri specific documentation, along with a workaround:
https://kando.menu/installation-on-linux/#furthermore-1

If that isn't it, let me know! I'll gladly work towards a fix with you!

[make-42]

Oh but the question was why...

[make-42]

I'd have to dig through Smithay and Niri specific code. But I suppose that it handles its own keybinds by probably just straight up reading from the keyboard with a separate mecanism than the rest of the Wayland session

[make-42]

The relevant logic is in Niri source at src/ui/hotkey_overlay.rs it seems like they spawn an overlay over the session that catches events from the keyboard.

[make-42]

To explain what Kando does when it simulates a keypress: it uses the zwp_virtual_keyboard_manager_v1 protocol to spawn a virtual keyboard to send keypresses from.

The problem is then probably due to how Niri handles those keybinds in src/ui/hotkey_overlay.rs (in Niri source) since the keypresses are actually sent properly by Kando.

[Zhaith-Izaliel]

Okay thank you for the replies. I thought it would be something feasable to fix, but this demands a huge refactor on Niri's logic to allow passthrough of these keybinds with the virtual keyboard protocol. I'm not a sure patch could be "easily" accepted upstream to fix this problem.

I wanted to be able to control Niri with my tablet pen on kando when I'm drawing, guess I will have to find a solution to get the last window ID in the command I'm using to simulate changing windows and stuff.

[make-42]

yeah that's probably the easiest solution! glad I could help!

[Zhaith-Izaliel]

It was great to have the "why" explained to me. I struggled to find the problem and thought it was directly in the wlroots backend of Kando and not on Niri itself lol. Thank you for helping me with this blockage <3