Waybar module for controlling brightness of an external display

config

// insert into ~/.config/waybar/config

    "custom/ddc_brightness": {
        // I don't even want to know why this works.
        // Change it to the following for your custom icons,
        // current format is a hack for Material Symbols to display normally:
        // "format": "{icon} {percentage}%",
        "format": "<span rise='-2pt' size='12pt'>{icon}</span> <span rise='1pt' size='10pt'>{percentage}%</span>",
        "format-icons": [
            // Icons from Google Material Symbols.
            // Put your icons here.
            "\ue3a6", "\ue3a7", "\ue3a8", "\ue3a9", "\ue3aa", "\ue3ab", "\ue3ac"
        ],
        "exec": "~/.config/waybar/waybar-ddc-module.sh",
        "return-type": "json",
        "on-scroll-up": "echo '+' > /tmp/waybar-ddc-module-rx",
        "on-scroll-down": "echo '-' > /tmp/waybar-ddc-module-rx",
        "on-click": "echo 'min' > /tmp/waybar-ddc-module-rx",
        "on-click-right": "echo 'max' > /tmp/waybar-ddc-module-rx",
        "tooltip": false,
    },

waybar-ddc-module.sh

#!/usr/bin/env bash

receive_pipe="/tmp/waybar-ddc-module-rx"
step=5

ddcutil_fast() {
    # adjust the bus number and the multiplier for your display
    # multiplier should be chosen so that it both works reliably and fast enough
    ddcutil --noverify --bus 5 --sleep-multiplier .03 "$@" 2>/dev/null
}

ddcutil_slow() {
    ddcutil --maxtries 15,15,15 "$@" 2>/dev/null
}

# takes ddcutil commandline as arguments
print_brightness() {
    if brightness=$("$@" -t getvcp 10); then
        brightness=$(echo "$brightness" | cut -d ' ' -f 4)
    else
        brightness=-1
    fi
    echo '{ "percentage":' "$brightness" '}'
}

rm -rf $receive_pipe
mkfifo $receive_pipe

# in case waybar restarted the script after restarting/replugging a monitor
print_brightness ddcutil_slow

while true; do
    read -r command < $receive_pipe
    case $command in
        + | -)
            ddcutil_fast setvcp 10 $command $step
            ;;
        max)
            ddcutil_fast setvcp 10 100 
            ;;
        min)
            ddcutil_fast setvcp 10 0
            ;;
    esac
    print_brightness ddcutil_fast
done

Dependencies:

• ddcutil (any version)