Turn off individual inactive monitors in multi-monitor setup

monitors.sh

#!/bin/bash


function get_monitors() {
    xrandr --listactivemonitors | awk 'NR!=1{print $4}'
}


function dim_monitor() {
    xrandr --output $1 --brightness 0
}


function brighten_monitor() {
    xrandr --output $1 --brightness 1
}


function get_pointer_monitor() {
    local X Y SCREEN WINDOW monitor size
    declare -a size

    # get mousepointer location and fill in vars X, Y, SCREEN, WINDOW
    eval "$(xdotool getmouselocation -shell 2>/dev/null)"
    for monitor in $(get_monitors); do
        # populate array size=(xmin xmax ymin ymax)
        size=($(xrandr \
            | awk "/${monitor}/" \
            | awk '{print $3}' \
            | awk -F'[x+]' '{print $3 " " $1+$3 " " $4 " " $2+$4}'))
        # figure out if pointer is in this monitor
        if (( $X >= ${size[0]} )) \
            && (( $X < ${size[1]} )) \
            && (( $Y >= ${size[2]} )) \
            && (( $Y < ${size[3]} ));
        then echo ${monitor}; fi
    done
}

# turn off monitor after threshold of seconds without pointer
export threshhold=600  # 10 minutes

# declare array such as [monitor_name]=seconds_since_cursor_was_present
declare -A counters
for m in $(get_monitors); do
    counters[$m]=0
done

while true; do
    # each second evaluate on which monitor is present pointer
    sleep 1
    current=$(get_pointer_monitor)
    for monitor in ${!counters[@]}; do
        if [[ $monitor == $current ]]; then
            # set counter to 0 and turn on where present
            ((counters[$monitor]=0))
            brighten_monitor $monitor
        else
            # increase counter where not present
            ((counters[$monitor]++))
        fi
        # turn off monitors after threshold
        (( ${counters[$monitor]} > $threshhold )) && dim_monitor $monitor
    done
done