Layer keys sometimes lead to duplicate keypresses #422

matklad · 2023-05-20T21:56:51Z

matklad
May 20, 2023

Describe the bug

This is a bit hard to describe, but I've noticed that I sometimes get two/three duplicate keys when using kanata.

Here's a video where I type type, but occasionally get typee or even typeee:

eee.mp4

What happens here is that, right after I type e, I press spc to switch the layers (I want to use my motion layer next). It feels like I get duplicated es if I press spc too fast.

Version

kanata 1.3.0

Relevant kanata configs

(defsrc
        grv  1    2    3    4    5    6    7    8    9     0    -    =    bspc
        tab  q    w    e    r    t    y    u    i    o     p    [    ]    \
        caps a    s    d    f    g    h    j    k    l     ;    '    ret
   lsft 102d z    x    c    v    b    n    m    ,    .     /    rsft
        lctl lmet lalt           spc            ralt rmet  rctl)

(deflayer qwerty
        grv  1    2    3    4    5    6    7    8    9     0    -    =    bspc
        tab  q    w    e    r    t    y    u    i    o     p    [    ]    \
        esc  a    s    d    f    g    h    j    k    l     ;    '    ret
    lsft @w0  @lc  @lm  @la v    b    n    m    @ra  @rm @rc  rsft
        lctl lmet lalt           @sp            ralt rmet  rctl)

(deflayer motion
        grv  1    2    3    4    5    6    7    8    9     0    -    =    bspc
        tab  q    w    e    r    t    y    pgup up   pgdn  p    [    ]    \
        esc  a    s    d    f    g    bspc lft  down rght del   '    ret
    lsft @w0  @lc  @lm  @la v    b    ret  m    home end   /    rsft
        lctl lmet lalt           @sp            ralt rmet  rctl)

(defalias
    sp (tap-hold 200 200 spc (layer-toggle motion))
    lc (tap-hold 200 200 z lctl)
    lm (tap-hold 200 200 x lmet)
    la (tap-hold 200 200 c lalt)
    ra (tap-hold 200 200 , lalt)
    rm (tap-hold 200 200 . rmet)
    rc (tap-hold 200 200 / rctl)
    w0 M-0)

Debug logs

Here's a debug log for typee (I am using workman layout, so the key names are not type):

22:52:22 [DEBUG] (2) kanata::kanata: key press     F
22:52:22 [DEBUG] (2) kanata::oskbd::linux: input ev: InputEvent { time: SystemTime { tv_sec: 0, tv_nsec: 0 }, kind: Key(KEY_F), value: 1 }
22:52:22 [DEBUG] (2) kanata::kanata: key press     H
22:52:22 [DEBUG] (2) kanata::oskbd::linux: input ev: InputEvent { time: SystemTime { tv_sec: 0, tv_nsec: 0 }, kind: Key(KEY_H), value: 1 }
22:52:22 [DEBUG] (2) kanata::kanata: key release   F
22:52:22 [DEBUG] (2) kanata::oskbd::linux: input ev: InputEvent { time: SystemTime { tv_sec: 0, tv_nsec: 0 }, kind: Key(KEY_F), value: 0 }
22:52:22 [DEBUG] (2) kanata::kanata: key press     O
22:52:22 [DEBUG] (2) kanata::oskbd::linux: input ev: InputEvent { time: SystemTime { tv_sec: 0, tv_nsec: 0 }, kind: Key(KEY_O), value: 1 }
22:52:22 [DEBUG] (2) kanata::kanata: key release   H
22:52:22 [DEBUG] (2) kanata::oskbd::linux: input ev: InputEvent { time: SystemTime { tv_sec: 0, tv_nsec: 0 }, kind: Key(KEY_H), value: 0 }
22:52:22 [DEBUG] (2) kanata::kanata: key press     K
22:52:22 [DEBUG] (2) kanata::oskbd::linux: input ev: InputEvent { time: SystemTime { tv_sec: 0, tv_nsec: 0 }, kind: Key(KEY_K), value: 1 }
22:52:22 [DEBUG] (2) kanata::kanata: key release   O
22:52:22 [DEBUG] (2) kanata::oskbd::linux: input ev: InputEvent { time: SystemTime { tv_sec: 0, tv_nsec: 0 }, kind: Key(KEY_O), value: 0 }
22:52:22 [INFO] Entered layer:

(deflayer motion
        grv  1    2    3    4    5    6    7    8    9     0    -    =    bspc
        tab  q    w    e    r    t    y    pgup up   pgdn  p    [    ]    \
        esc  a    s    d    f    g    bspc lft  down rght del   '    ret
    lsft @w0  @lc  @lm  @la v    b    ret  m    home end   /    rsft
        lctl lmet lalt           @sp            ralt rmet  rctl)
22:52:22 [DEBUG] (2) kanata::kanata: key release   K
22:52:22 [DEBUG] (2) kanata::oskbd::linux: input ev: InputEvent { time: SystemTime { tv_sec: 0, tv_nsec: 0 }, kind: Key(KEY_K), value: 0 }
22:52:22 [DEBUG] (2) kanata::kanata: key outs for active layer-while-held: [KEY_SPACE];
22:52:22 [DEBUG] (2) kanata::kanata: key outs for default layer: [KEY_SPACE];
22:52:22 [DEBUG] (2) kanata::kanata: key outs for active layer-while-held: [KEY_SPACE];
22:52:22 [DEBUG] (2) kanata::kanata: key outs for default layer: [KEY_SPACE];
22:52:22 [DEBUG] (2) kanata::kanata: key outs for active layer-while-held: [KEY_SPACE];
22:52:22 [DEBUG] (2) kanata::kanata: key outs for default layer: [KEY_SPACE];
22:52:22 [DEBUG] (2) kanata::kanata: key outs for active layer-while-held: [KEY_SPACE];
22:52:22 [DEBUG] (2) kanata::kanata: key outs for default layer: [KEY_SPACE];
22:52:23 [INFO] Entered layer:

(deflayer qwerty
        grv  1    2    3    4    5    6    7    8    9     0    -    =    bspc
        tab  q    w    e    r    t    y    u    i    o     p    [    ]    \
        esc  a    s    d    f    g    h    j    k    l     ;    '    ret
    lsft @w0  @lc  @lm  @la v    b    n    m    @ra  @rm @rc  rsft
        lctl lmet lalt           @sp            ralt rmet  rctl)

Now that I've looked at it, here's a better log where I get just eee:

22:54:16 [DEBUG] (2) kanata::kanata: key press     K
22:54:16 [DEBUG] (2) kanata::oskbd::linux: input ev: InputEvent { time: SystemTime { tv_sec: 0, tv_nsec: 0 }, kind: Key(KEY_K), value: 1 }
22:54:16 [INFO] Entered layer:

(deflayer motion
        grv  1    2    3    4    5    6    7    8    9     0    -    =    bspc
        tab  q    w    e    r    t    y    pgup up   pgdn  p    [    ]    \
        esc  a    s    d    f    g    bspc lft  down rght del   '    ret
    lsft @w0  @lc  @lm  @la v    b    ret  m    home end   /    rsft
        lctl lmet lalt           @sp            ralt rmet  rctl)
22:54:16 [DEBUG] (2) kanata::kanata: key release   K
22:54:16 [DEBUG] (2) kanata::oskbd::linux: input ev: InputEvent { time: SystemTime { tv_sec: 0, tv_nsec: 0 }, kind: Key(KEY_K), value: 0 }
22:54:16 [DEBUG] (2) kanata::kanata: key outs for active layer-while-held: [KEY_SPACE];
22:54:16 [DEBUG] (2) kanata::kanata: key outs for default layer: [KEY_SPACE];
22:54:16 [DEBUG] (2) kanata::kanata: key outs for active layer-while-held: [KEY_SPACE];
22:54:16 [DEBUG] (2) kanata::kanata: key outs for default layer: [KEY_SPACE];
22:54:16 [DEBUG] (2) kanata::kanata: key outs for active layer-while-held: [KEY_SPACE];
22:54:16 [DEBUG] (2) kanata::kanata: key outs for default layer: [KEY_SPACE];
22:54:16 [DEBUG] (2) kanata::kanata: key outs for active layer-while-held: [KEY_SPACE];
22:54:16 [DEBUG] (2) kanata::kanata: key outs for default layer: [KEY_SPACE];
22:54:16 [DEBUG] (2) kanata::kanata: key outs for active layer-while-held: [KEY_SPACE];
22:54:16 [DEBUG] (2) kanata::kanata: key outs for default layer: [KEY_SPACE];
22:54:16 [DEBUG] (2) kanata::kanata: key outs for active layer-while-held: [KEY_SPACE];
22:54:16 [DEBUG] (2) kanata::kanata: key outs for default layer: [KEY_SPACE];
22:54:16 [DEBUG] (2) kanata::kanata: key outs for active layer-while-held: [KEY_SPACE];
22:54:16 [DEBUG] (2) kanata::kanata: key outs for default layer: [KEY_SPACE];
22:54:16 [DEBUG] (2) kanata::kanata: key outs for active layer-while-held: [KEY_SPACE];
22:54:16 [DEBUG] (2) kanata::kanata: key outs for default layer: [KEY_SPACE];
22:54:16 [DEBUG] (2) kanata::kanata: key outs for active layer-while-held: [KEY_SPACE];
22:54:16 [DEBUG] (2) kanata::kanata: key outs for default layer: [KEY_SPACE];
22:54:16 [DEBUG] (2) kanata::kanata: key outs for active layer-while-held: [KEY_SPACE];
22:54:16 [DEBUG] (2) kanata::kanata: key outs for default layer: [KEY_SPACE];
22:54:16 [DEBUG] (2) kanata::kanata: key outs for active layer-while-held: [KEY_SPACE];
22:54:16 [DEBUG] (2) kanata::kanata: key outs for default layer: [KEY_SPACE];
22:54:16 [DEBUG] (2) kanata::kanata: key outs for active layer-while-held: [KEY_SPACE];
22:54:16 [DEBUG] (2) kanata::kanata: key outs for default layer: [KEY_SPACE];
22:54:16 [INFO] Entered layer:

(deflayer qwerty
        grv  1    2    3    4    5    6    7    8    9     0    -    =    bspc
        tab  q    w    e    r    t    y    u    i    o     p    [    ]    \
        esc  a    s    d    f    g    h    j    k    l     ;    '    ret
    lsft @w0  @lc  @lm  @la v    b    n    m    @ra  @rm @rc  rsft
        lctl lmet lalt           @sp            ralt rmet  rctl)

It seems the sequence of events here is:

I depress e
I depress spc
I release e

So the keypress straddles a layer switch, and that somehow causes triplication of the event.

Operating system

Linux (NixOS), wayland

matklad · 2023-05-20T22:04:32Z

matklad
May 20, 2023
Author

🤔 interestingly, if I bump my repeat delay in plasma 10x to 2.5 seconds, the effect goes away (my default delay is fairly tight 250ms). Maaaybe the problem exists between the chair and the keyboard and I just keep the key pressed too long? I am not sure -- I am not getting "spurious" repeats outside of layer switching. Still, I guess bumping the repeat delay to 400ms might be a good-enough work-around for me?

0 replies

jtroo · 2023-05-21T02:49:50Z

jtroo
May 21, 2023
Maintainer

The answer to this is a little more subtle and perhaps interesting than PEBCAK vs. a kanata bug.

On Linux, kanata may choose to send a value: 2 (repeat) event when it receives a value: 2 event from the kernel on the /dev/input device. This repeat event occurs when the kernel decides that a key repeat should occur. Kanata sending such an event would be seen in a line that looks like this from the sample (but with value: 2):

22:54:16 [DEBUG] (2) kanata::oskbd::linux: input ev: InputEvent { time: SystemTime { tv_sec: 0, tv_nsec: 0 }, kind: Key(KEY_K), value: 1 }

Doing it this way allows key repeat in a console-only scenario with no desktop environment (DE). I don't see any of these events being sent which means that kanata isn't activating key repeats of its own volition.

From what I've read in the past, DEs may ignore these value: 2 events and have their own repeat timings, purely based on the value: 1 (press) event and the time elapsed until value: 0 (release) happens. This appears to be what's happening here.

The kernel knows that space has been pressed and is being held, so it's sending value: 2 events for space to kanata. This can be inferred in the log messages below, which is kanata checking if it should send a repeat event. Kanata decides not to send a repeat event itself, because the physical space key corresponds to a layer-while-held action in this moment, rather than a "typing space" action.

22:54:16 [DEBUG] (2) kanata::kanata: key outs for default layer: [KEY_SPACE];
22:54:16 [DEBUG] (2) kanata::kanata: key outs for active layer-while-held: [KEY_SPACE];

However, the DE has no way to know that the space key has actually been pressed - it thinks the physical K is the only key being pressed, and so will do key repeats for it, even though space has already been pressed. This is different compared to if the DE knew that space was pressed. This should be able to be seen when holding A and quickly tapping B for example - A no longer repeats. The way you think these key sequences should behave is correct, because that's how it behaves without this interesting interaction between the kernel, kanata, and the DE.

Another different workaround you might be able to do in kanata is to add a multi to space and send a key that behaves like a no-op, maybe f24. Something like (defalias sp (multi f24 (tap-hold ...))).

~~Or perhaps the DE has a way to configure itself to ignore its builtin repeat mechanism and rely on the input device's value: 2 mechanism.~~ I haven't been able to find a way to get the DE to repeat based on the value: 2 events, and I don't think such a mechanism exists.

0 replies

ArijanJ · 2023-08-28T19:57:20Z

ArijanJ
Aug 28, 2023

(defalias sp (multi f24 (tap-hold ...)))

Oh my god, this has been annoying me for ages, thank you for figuring it out!
I know it doesn't affect many people unless the repeat delay is super low, but maybe we should document it somewhere near the tap-hold family?

2 replies

jtroo Aug 28, 2023
Maintainer

Yea that would be a welcome doc addition 🙂

Please file a PR to update the doc or file an issue for the doc work, thanks!

mattiasJohnson Sep 16, 2023

Just coming over from TouchCursor and this was a must-have feature for me. This would affect every user who wants to use space for changing layers (+who has a fast repeat rate). I do not feel I have the knowledge for adding this properly to the docs, would you be able to add this part?

edit: created issue #562

xDarksome · 2024-02-13T18:04:25Z

xDarksome
Feb 13, 2024

Is it possible that the multi hack stopped working? I just recently started using kanata, encountered the issue, found this discussion, applied the hack. And I'm still experiencing the issue, although perceivably less.

4 replies

jtroo Feb 13, 2024
Maintainer

If it did stop working, that would probably be in the desktop environment and not kanata.

I would need more detail about precise desktop/application outputted keysyms corresponding to a physical input sequence, with kanata --debug logs to know more though.

xDarksome Feb 13, 2024

Thanks for a quick reply!

OS: NixOS
Window manager: sway (repeat delay 200ms)
Terminal emulator: wezterm
Editor: helix

Scenario:

press s+d+f in a single stroke
press space

This sometimes results in the following output

sdfff

Log

2024-02-13T19:14:15.732290208Z [DEBUG] (2) kanata::kanata: process recv ev KeyEvent { code: KEY_S, value: Press }
2024-02-13T19:14:15.732314275Z [DEBUG] (2) kanata::kanata: key press     S
2024-02-13T19:14:15.732317149Z [DEBUG] (2) kanata::oskbd::linux: send to uinput: InputEvent { time: SystemTime { tv_sec: 0, tv_nsec: 0 }, kind: Key(KEY_S), value: 1 }
2024-02-13T19:14:15.738099531Z [DEBUG] (2) kanata::kanata: process recv ev KeyEvent { code: KEY_D, value: Press }
2024-02-13T19:14:15.738137074Z [DEBUG] (2) kanata::kanata: key press     D
2024-02-13T19:14:15.738138622Z [DEBUG] (2) kanata::oskbd::linux: send to uinput: InputEvent { time: SystemTime { tv_sec: 0, tv_nsec: 0 }, kind: Key(KEY_D), value: 1 }
2024-02-13T19:14:15.75704081Z [DEBUG] (2) kanata::kanata: process recv ev KeyEvent { code: KEY_F, value: Press }
2024-02-13T19:14:15.757073135Z [DEBUG] (2) kanata::kanata: key press     F
2024-02-13T19:14:15.757080464Z [DEBUG] (2) kanata::oskbd::linux: send to uinput: InputEvent { time: SystemTime { tv_sec: 0, tv_nsec: 0 }, kind: Key(KEY_F), value: 1 }
2024-02-13T19:14:15.845169214Z [DEBUG] (2) kanata::kanata: process recv ev KeyEvent { code: KEY_SPACE, value: Press }
2024-02-13T19:14:15.845188682Z [DEBUG] (2) kanata::kanata: key press     F24
2024-02-13T19:14:15.845191156Z [DEBUG] (2) kanata::oskbd::linux: send to uinput: InputEvent { time: SystemTime { tv_sec: 0, tv_nsec: 0 }, kind: Key(KEY_F24), value: 1 }
2024-02-13T19:14:15.901843588Z [DEBUG] (2) kanata::kanata: process recv ev KeyEvent { code: KEY_S, value: Release }
2024-02-13T19:14:15.918811499Z [DEBUG] (2) kanata::kanata: process recv ev KeyEvent { code: KEY_D, value: Release }
2024-02-13T19:14:15.943345437Z [DEBUG] (2) kanata::kanata: process recv ev KeyEvent { code: KEY_F, value: Release }
2024-02-13T19:14:15.970953419Z [DEBUG] (2) kanata::kanata: process recv ev KeyEvent { code: KEY_SPACE, value: Release }
2024-02-13T19:14:15.97099237Z [DEBUG] (2) kanata::kanata: key press     Space
2024-02-13T19:14:15.970994453Z [DEBUG] (2) kanata::oskbd::linux: send to uinput: InputEvent { time: SystemTime { tv_sec: 0, tv_nsec: 0 }, kind: Key(KEY_SPACE), value: 1 }
2024-02-13T19:14:15.972082999Z [DEBUG] (2) kanata::kanata: key release   S
2024-02-13T19:14:15.972115848Z [DEBUG] (2) kanata::oskbd::linux: send to uinput: InputEvent { time: SystemTime { tv_sec: 0, tv_nsec: 0 }, kind: Key(KEY_S), value: 0 }
2024-02-13T19:14:15.973215114Z [DEBUG] (2) kanata::kanata: key release   D
2024-02-13T19:14:15.97323148Z [DEBUG] (2) kanata::oskbd::linux: send to uinput: InputEvent { time: SystemTime { tv_sec: 0, tv_nsec: 0 }, kind: Key(KEY_D), value: 0 }
2024-02-13T19:14:15.974300012Z [DEBUG] (2) kanata::kanata: key release   F
2024-02-13T19:14:15.974302491Z [DEBUG] (2) kanata::oskbd::linux: send to uinput: InputEvent { time: SystemTime { tv_sec: 0, tv_nsec: 0 }, kind: Key(KEY_F), value: 0 }
2024-02-13T19:14:15.975377831Z [DEBUG] (2) kanata::kanata: key release   F24
2024-02-13T19:14:15.975393999Z [DEBUG] (2) kanata::oskbd::linux: send to uinput: InputEvent { time: SystemTime { tv_sec: 0, tv_nsec: 0 }, kind: Key(KEY_F24), value: 0 }
2024-02-13T19:14:15.975402302Z [DEBUG] (2) kanata::kanata: key release   Space
2024-02-13T19:14:15.97540347Z [DEBUG] (2) kanata::oskbd::linux: send to uinput: InputEvent { time: SystemTime { tv_sec: 0, tv_nsec: 0 }, kind: Key(KEY_SPACE), value: 0 }

Config: https://github.com/xDarksome/nixos-config/blob/2f402aea858d46afc7f3e92b338fd4b71656b3de/kanata/asus.kbd

jtroo Feb 13, 2024
Maintainer

I don't see anything incorrect in the Kanata behaviour according to the debug logs. It's not a keyboard chattering issue either - the events all look as expected. So unfortunately, to my observation at least, it seems like there's something at the desktop or application layer that's behaving poorly.

xDarksome Feb 14, 2024

I see, probably wezterm/helix are doing something weird. I'll investigate, thanks!

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Layer keys sometimes lead to duplicate keypresses #422

matklad May 20, 2023

Replies: 4 comments · 6 replies

matklad May 20, 2023 Author

jtroo May 21, 2023 Maintainer

ArijanJ Aug 28, 2023

jtroo Aug 28, 2023 Maintainer

mattiasJohnson Sep 16, 2023

xDarksome Feb 13, 2024

jtroo Feb 13, 2024 Maintainer

xDarksome Feb 13, 2024

jtroo Feb 13, 2024 Maintainer

xDarksome Feb 14, 2024

matklad
May 20, 2023

Replies: 4 comments 6 replies

matklad
May 20, 2023
Author

jtroo
May 21, 2023
Maintainer

ArijanJ
Aug 28, 2023

jtroo Aug 28, 2023
Maintainer

xDarksome
Feb 13, 2024

jtroo Feb 13, 2024
Maintainer

jtroo Feb 13, 2024
Maintainer