Trouble implementing home row mods

[maykot]

I've been trying to implement home row mods using keymapper and I hit a wall.

My first naive implementation was just something like this: A{Any} >> Meta{Any}. Which is no good, it makes typing very difficult because rolling A Any (i.e. press A, press Any, release A, release Any) causes Meta{Any} to be sent. To fix this I've been trying to implement something like kanata's tap-hold-release, without success. But now I'm not even sure that's a good idea.

Ideally I'd want A to act as Meta whenever the following sequence of events happens: press A, press Any, release Any (with other mods optionally held as well). And importantly, the following sequence should not trigger Meta and should default to normal behavior: press A, press Any, release A.

Has anyone else implemented this already? Any help would be much appreciated.

[ristomatti]

I have not implemented Home Row mods specifically, but I have implemented modifier like mappings on a couple of alpha keys. I've been using them for quite some time now with neglible effect on my typing. My full config is on GitHub but the config is quite complex and might not be up-to-date on this part.

I've tried to extract the relevant bits of my most used one that allows using HJKL as arrow keys while holding E. I didn't test this by itself though.

# Any modifier
Modifier    = Control | Meta | Shift | Alt | AltGr

# Cursor movement
CursorLeft  = H
CursorDown  = J
CursorUp    = K
CursorRight = L

# Virtual mods
EditMode    = Virtual20

# Alpha mods
Edit        = E

# Macros
Tap         = $0{!120ms}
Hold        = $0{130ms}

# Edit mode
[modifier = "EditMode"]
  CursorUp    >> ArrowUp
  CursorLeft  >> ArrowLeft
  CursorDown  >> ArrowDown
  CursorRight >> ArrowRight
  Space       >> Space

[modifier = "!Modifier !Space"]
  ? Tap[Edit] >> Edit
  Hold[Edit]  >> EditMode ^ EditMode

Negated Modifier is obviously to avoid triggering the mode when E is used in combination of standard modifiers.

I don't remember exactly if the stuff involving Space was related to my usage of Space as the Meta key further down the config, or if it caused issues with this particular mapping. It might not be needed.

[ristomatti]

I hate to say this but this is essentially exactly what I first tried as well and has the same issue I had as well. Depending on your shortcut usage patterns it might not be that big of an issue though. Triggering output of Meta{Shift{1}} works, but can you get it to output Control{Alt{1}} or Alt{Shift{1}} (using HR mods keys)? I can't.

As it stands I cannot repeat a home row key by holding it down, that's just unavoidable in this setup. To address this I was planning on adding something along the lines of HRMetaL !120ms HRMetaL >> HRMetaL HRMetaL to the top of the default section. The intention was that double tapping a key and holding it would trigger the repeat of the original key.

I had the exact same thought process and encountered the same issue. In fact, I've ran across this earlier on with my own config. If you only need to do this occasionally, you can get a key to repeat if you first type some key that doesn't output or do anything in the given context, then quickly follow up with the key you want to repeat. But perhaps a better workaround is to modify your config to include something like this:

RepeatMod     = Virtual50

[modifier = "RepeatMod"]
    HRMod >> HRMod

[default]
    Hold["Tab"] >> RepeatMod ^ RepeatMod

    ? Tap[HRMod]                    >> HRMod

You could also try if using [stage] either before or after the HRM section and try if you can come up with something that works when evaluated in a different stage.

Edit: changed RepeatMod to a virtual modifier (should not edit after pasting a working snippet)

[ristomatti]

Are you on KDE too?

Nope, Gnome with i3 WM on Ubuntu 20.04.

[ristomatti]

I also verified now with evtest that Shift+Alt is just that, Shift and Alt on the input device level. I also tried Finnish layout and still get Meta_L, so perhaps it's something happening on X11 level 🤷.

[maykot]

I hate to say this but this is essentially exactly what I first tried as well and has the same issue I had as well. Depending on your shortcut usage patterns it might not be that big of an issue though. Triggering output of Meta{Shift{1}} works, but can you get it to output Control{Alt{1}} or Alt{Shift{1}} (using HR mods keys)? I can't.

You're totally right. Now I'm 100% certain my config is gaslighting me. I was sure I had tested J{K{V}} or K{J{V}} and it correctly pasted to the terminal (i.e. Control{Shift{V}}), but no, it definitely doesn't in either order. It's kinda funny that some combinations work though. A{D{ArrowLeft}} is correctly interpreted as Meta{Control{ArrowLeft}}, but D{A{ArrowLeft}} isn't. I guess it's back to the drawing board then.

But perhaps a better workaround is to modify your config to include something like this:

Oh, that might also be a nice alternative. I'll try this once I have a working config.

[maykot]

I also verified now with evtest that Shift+Alt is just that, Shift and Alt on the input device level. I also tried Finnish layout and still get Meta_L, so perhaps it's something happening on X11 level 🤷.

I'm on Wayland. I just checked keyzz on two different browsers, one running directly on Wayland and the other running under Xwayland, the issue only happened on the browser running under Xwayland. So yeah, it seems it's an X11 issue.

[houmain]

Does A{E !E} >> Meta{E} behave as you intend?
I just tried A{Any !Any} >> Meta{Any} but that does not work yet.

[maykot]

Would your ideal setup also support holding down multiple Home Row Mods?

Yes, definitely.

How would e.g. Meta{F} be handled when A{F} if we assume A to be Meta and F to be another mod key?

This is a good example. I don't know how to implement it in keymapper, but in terms of key press and release the logic would be something like this:
When a home row mod key is pressed defer its evaluation until a key is pressed and then released with no other events in between. The key that was pressed and then released retains its default value, the rest are treated as mods. In the example above there are a few ways A and F could be stringed together, +A +F -F >> +Meta +F -F, +F +A -A >> +Control +A -A (assuming F is Control), +A +F -A >> +A +F -A.
This is probably missing a bunch of edge cases that I'm very likely overlooking, but the rough idea is there.

[MatthiasGrandl]

@maykot have you found a solution for combining multiple home row mods? was super happy initially after migrating my config from kmonad to keymapper until I stumbled across this limitation lol

[maykot]

No, I haven't. But I haven't tried ristomatti's latest suggestion yet.

[MatthiasGrandl]

I guess it probably does work, just wanted to avoid defining all combinations separately haha.

[MatthiasGrandl]

PS: I just did and it seems to be working pretty well. If anyone has suggestions for improvements, lemme know.

# Homerow Mods
FakeAlt = S | L
FakeControl = D | K
FakeShift = F | J
FakeMeta = A | Semicolon

FakeMeta{Any !Any} >> Meta{Any}
FakeAlt{Any !Any} >> Alt{Any}
FakeControl{Any !Any} >> Control{Any}
FakeShift{Any !Any} >> Shift{Any}

# All combinations of 4
(FakeMeta FakeAlt FakeControl FakeShift){Any !Any} >> (Meta Alt Control Shift){Any}

# All combinations of 3
(FakeMeta FakeAlt FakeControl){Any !Any} >> (Meta Alt Control){Any}
(FakeMeta FakeAlt FakeShift){Any !Any} >> (Meta Alt Shift){Any}
(FakeMeta FakeControl FakeShift){Any !Any} >> (Meta Control Shift){Any}
(FakeAlt FakeControl FakeShift){Any !Any} >> (Alt Control Shift){Any}

# All combinations of 2
(FakeMeta FakeAlt){Any !Any} >> (Meta Alt){Any}
(FakeMeta FakeControl){Any !Any} >> (Meta Control){Any}
(FakeMeta FakeShift){Any !Any} >> (Meta Shift){Any}
(FakeAlt FakeControl){Any !Any} >> (Alt Control){Any}
(FakeAlt FakeShift){Any !Any} >> (Alt Shift){Any}
(FakeControl FakeShift){Any !Any} >> (Control Shift){Any}

[ristomatti]

@maykot If you're still on this quest, you might want to take a look at #210 (comment) in case that config would help in solving this. (I didn't try it myself though)

[maykot]

Oh, sorry, I missed this. My New Year was a bit hectic. I'll give it a try when I have sometime to play around with my config again.