Migrating .xmodmaprc to Wayland: remap arbitrary keys
April 5, 2022
.xmodmaprc to Wayland: remap arbitrary keysApril 5, 2022
I recently moved from X11 to Wayland,
and one of my challenges that came with it was to find an alternative
for my .xmodmaprc, that I used for two purposes:
Since xmodmap is a X11 thing, I needed to find a Wayland alternative
to this.
It seems that the common answer is to directly modify the XKB database
in /usr/share/X11/xkb, but according to this Stack Exchange post
(referencing the XKB docs),
we learn that we can customize XKB symbols in
~/.config/xkb/symbols/<name> and XKB rules in
~/.config/xkb/rules/evdev. Great.
This is something commonly done with xmodmap, and there’s very little
documentation of alternative solutions, but I found this answer
showing how to achieve that by modifying the XKB symbols in
/usr/share/X11/xkb/symbols/ctrl:
xkb_symbols "swap_ralt_rctl" {
replace key <RALT> { [ Control_R, Control_R ] };
replace key <RCTL> { [ Alt_R, Meta_R ] };
};
Because I just learnt I could modify stuff in ~/.config/xkb/symbols
instead, I added this code to ~/.config/xkb/symbols/ctrl.
Then in my Sway config (this will vary depending on your window manager
or desktop environment), I enabled the ctrl:swap_ralt_rctl option for
my keyboard:
input type:keyboard {
xkb_options ctrl:swap_lalt_lctl
}
And this worked! But it shouldn’t have. I realized later (when
adding another option with a different name) that it is required to
also add a matching entry to the xkb/rules/evdev file. So why did it
work?
It turns out that there was already a native XKB option with that exact
name (in /usr/share/X11/xkb/symbols/ctrl and
/usr/share/X11/xkb/rules/evdev), and that’s why the name was
recognized. And unsurprisingly, that native option does exactly what I
want, so I could get rid of that ~/.config/xkb/symbols/ctrl file
altogether and just use ctrl:swap_lalt_lctl in my Sway config. 😆
Now on to the hardest part. My ~/.xmodmaprc used to look like this,
essentially, mapping F5 to what Fn + F5
would do, and inversely, and so on for a number of function keys that I
use.
keycode 71 = XF86MonBrightnessDown
keycode 232 = F5
keycode 72 = XF86MonBrightnessUp
keycode 233 = F6
keycode 73 = XF86ScreenSaver
keycode 160 = F7
keycode 76 = XF86AudioMute
keycode 121 = F10
keycode 95 = XF86AudioLowerVolume
keycode 122 = F11
keycode 96 = XF86AudioRaiseVolume
keycode 123 = F12
With a bit of trial and error, and looking at the
/usr/share/X11/xkb/keycodes/evdev file, I could figure what were the
corresponding XKB keys for the codes above:
<FK01> = 67;
<FK02> = 68;
<FK03> = 69;
<FK04> = 70;
<FK05> = 71;
<FK06> = 72;
<FK07> = 73;
<FK08> = 74;
<FK09> = 75;
<FK10> = 76;
<FK11> = 95;
<FK12> = 96;
...
<MUTE> = 121;
<VOL-> = 122;
<VOL+> = 123;
...
alias <I121> = <MUTE>; // #define KEY_MUTE 113
alias <I122> = <VOL->; // #define KEY_VOLUMEDOWN 114
alias <I123> = <VOL+>; // #define KEY_VOLUMEUP 115
...
<I160> = 160; // #define KEY_COFFEE 152
<I232> = 232; // #define KEY_BRIGHTNESSDOWN 224
<I233> = 233; // #define KEY_BRIGHTNESSUP 225
Leading me to the write following ~/.config/xkb/symbols/ctrl:
partial modifier_keys
xkb_symbols "swap_fn_keys" {
replace key <FK05> { [ XF86MonBrightnessDown ] };
replace key <FK06> { [ XF86MonBrightnessUp ] };
replace key <FK07> { [ XF86ScreenSaver ] };
replace key <FK09> { [ XF86TouchpadToggle ] };
replace key <FK10> { [ XF86AudioMute ] };
replace key <FK11> { [ XF86AudioLowerVolume ] };
replace key <FK12> { [ XF86AudioRaiseVolume ] };
replace key <I232> { [ F5 ] };
replace key <I233> { [ F6 ] };
replace key <I160> { [ F7 ] };
replace key <I199> { [ F9 ] };
replace key <I121> { [ F10 ] };
replace key <I122> { [ F11 ] };
replace key <I123> { [ F12 ] };
};
And this time because swap_fn_keys is a new entry, I did need to add
it to ~/.config/xkb/rules/evdev. According to the
XKB docs,
this is done with the following pattern:
! option = symbols
ctrl:swap_fn_keys = +ctrl(swap_fn_keys)
! include %S/evdev
And I can finally include it to my Sway keyboard options:
input type:keyboard {
xkb_options ctrl:swap_lalt_lctl,ctrl:swap_fn_keys
}