input: add Super as alternative for Mod4

[Ferdi265]

This PR implements alternative human-readable names for the logo key (Mod4) as proposed in #8084.

Implemented in this PR are the names "Super", "Meta", and "Logo".

This is the first time the supported modifier names have been touched since #153, almost 9 years ago (besides moving the code around into different files and switching from wlc to wlroots).

[emersion]

I'd be fine with adding a more user-friendly name, but would prefer not to add a whole bunch of aliases that mean the same thing. My preference would be to follow the libxkbcommon naming here.

Also this needs a man page update as well.

[Ferdi265]

Right. So just "Logo", plus documentation updates IIUC.

I expected this and I'm fine with any of these, I mostly made this PR so broad so all options are on the table.

Will adjust accordingly.

[Ferdi265]

updated to allow only "Logo" instead of "Super", "Meta", and "Logo".

I haven't found any explanation of modifier names in the man pages except a few examples. Would you accept a separate PR adding such a section that explains all of the supported modifier names or would you like this to be done in this PR? Should we update examples in the man pages or config to use symbolic names where possible?

(The branch name doesn't fit any more, but that's on me, and renaming a branch while keeping the PR attached doesn't work IIRC, so so be it.)

[Ferdi265]

ahh, sorry, I was confused by <xkbcommon-names.h> calling the key "LOGO", while the rest of xkbcommon seems to call it Super or Meta (notably, here and here). I'm not 100% sure which one to take.

I'm leaving this choice to you. I'm fine with either of them, so please tell me which one you prefer.

(also, changing this to Super for now, which seems to be the recommended choice for Mod4 according to here)

[Ferdi265]

Modifier documentation is now in branch feature-modifier-docs. I added it to the documentation for bindsym, which is the only place I found that explicitly talks about XKB keysyms with regards to keybindings.

I also noticed that AltGr is also missing a human readable alias, so I added that in feature-altgr-modifier. Not sure if the sway project wants/needs that as well, but it's there if needed. Let me know and I will make a PR.

[rpigott]

Is there a way we can just get the virtual modifier names from the keymap to alias their real modifiers? That would basically implement this then, right?

[emersion]

Is there a way we can just get the virtual modifier names from the keymap to alias their real modifiers? That would basically implement this then, right?

You mean xkb_keymap_mod_get_name()? This returns the names used by XKB_MOD_NAME_* and we already have these listed.

I haven't found any explanation of modifier names in the man pages except a few examples. Would you accept a separate PR adding such a section that explains all of the supported modifier names or would you like this to be done in this PR? Should we update examples in the man pages or config to use symbolic names where possible?

Oh, sorry, I thought we had these documented already but it doesn't seem like it. Either is fine!

[Ferdi265]

I haven't found any explanation of modifier names in the man pages except a few examples. Would you accept a separate PR adding such a section that explains all of the supported modifier names or would you like this to be done in this PR? Should we update examples in the man pages or config to use symbolic names where possible?

Oh, sorry, I thought we had these documented already but it doesn't seem like it. Either is fine!

I made a new PR documenting the existing modifiers (#8087) and rebased this one on top of that in addition to documenting the Super modifier here.

Intended merge order is #8087 followed by #8085 (this PR).

[rpigott]

Super, Meta, etc. are virtual modifier names. They're at least present in the (standard US) keymap I can extract from xwayland, along with their real modifier associations. So, IIUC, it is possible by manual inspection of the keymap to map those names uniquely to real modifiers (Mod1, Mod4). I don't see any xkbcommon api related to virtual modifiers though, so maybe I haven't fully understood their purpose.

[emersion]

Yeah, I can see e.g. "Super" defined here:

• https://gitlab.freedesktop.org/xkeyboard-config/xkeyboard-config/-/blob/022c3ca1db12e505cbd5ce8bf19c432d6a70c7e5/types/pc#L22
• https://gitlab.freedesktop.org/xkeyboard-config/xkeyboard-config/-/blob/022c3ca1db12e505cbd5ce8bf19c432d6a70c7e5/compat/misc#L56

But yeah, I don't see any way to extract this string from the XKB API.

[Ferdi265]

Yeah, I can see e.g. "Super" defined here:

* https://gitlab.freedesktop.org/xkeyboard-config/xkeyboard-config/-/blob/022c3ca1db12e505cbd5ce8bf19c432d6a70c7e5/types/pc#L22

* https://gitlab.freedesktop.org/xkeyboard-config/xkeyboard-config/-/blob/022c3ca1db12e505cbd5ce8bf19c432d6a70c7e5/compat/misc#L56

But yeah, I don't see any way to extract this string from the XKB API.

xkb_keymap_num_mods(keymap) returns the number of modifiers and with de and us I see the virtual modifier names from xkb_keymap_mod_get_name(keymap, index) starting at modifier index 8. I don't know how to get the mappings to real modifiers though.

[rpigott]

Seems like XKB (OG X Keyboard Extension) had something like this [1][2]

[1] https://man.archlinux.org/man/XkbGetVirtualMods.3
[2] https://man.archlinux.org/man/XkbVirtualModsToReal.3

[Ferdi265]

rebased since #8087 was merged

[emersion]

Thanks!

[WhyNotHugo]

Thank you!