Switching keyboard layouts quickly and efficiently has been a long-standing problem for me. My latest attempt is by utilizing the extra buttons, that some mice and trackballs have.
The solution that eventually worked for me, was switching between two layouts for every button. The decision to switch is made based on the current active layout.
This allows me to switch between the second and third layout, by pressing the corresponding buttons, without going through the default layout.
Getting the current layout was surprisingly involved though, and I ended up with this.
setxkbmap -query | grep -P 'layout:\s+\K[a-z]{2}' -o
The -P instructs grep to use Perl style regular expressions, and
the revelation for me that did the trick was \K, which effectively
discards what comes before from getting captured.
I also need to choose variants for every layout, so the full
switchkb script ended up like this.
SWITCH=${1:-us}
current=$(setxkbmap -query | grep -P 'layout:\s+\K[a-z]{2}' -o)
if [[ "${current}" == "${SWITCH}" ]] ; then
setxkbmap us altgr-intl
exit 0
fi
case "${SWITCH}" in
am)
setxkbmap am western
;;
ru)
setxkbmap ru phonetic
;;
us|*)
setxkbmap us altgr-intl
;;
esac
Most mice have a button under the scroll wheel, equivalent to
double-click, this is button2. Other button names are usually
button8, button9, etc. They can be retrieved with xev.
Mapping the mouse buttons to the switch script was simple enough with
sxhkd.
button2
switchkb am
button8
switchkb ru
The above can be rewritten simply like this:
button{2,8}
switchkb {am,ru}
Worth noting here, that I find sxhkd indispensable, especially with
tiling window managers. In addition to its powerful and concise config
style, it makes using multiple window managers trivial, by making the
keyboard mapping definitions independent.