backlit.sh

#!/bin/bash
# Wrapper for brightnessctl, adding:
# - custom maximum value (useful when you override PWM settings)
# - smooooooooooooooooooooooooooooooooothiness
# - desktop notification
#
# Author: Alexander Pushkov <backlit@ale.sh>
# SPDX-License-Identifier: Apache-2.0 OR ISC

DELTA=2
STEP=35
MAX=560

NOTIFICATION_ICON="contrast"
NOTIFICATION_EXPIRE_TIME=3000
NOTIFICATION_ID_PATH="${XDG_RUNTIME_DIR}/backlit_notification_id"

notify() {
  touch "${NOTIFICATION_ID_PATH}"
  notification_id="$(cat ${NOTIFICATION_ID_PATH})"

  if [[ "${notification_id}x" -eq "x" ]]; then
    notification_id="0"
  fi

  gdbus call --session \
    --dest org.freedesktop.Notifications \
    --object-path /org/freedesktop/Notifications \
    --method org.freedesktop.Notifications.Notify \
    -- "" "${notification_id}" "${NOTIFICATION_ICON}" "" "" "[]" "{\"value\": <int32 ${1}>}" "int32 ${NOTIFICATION_EXPIRE_TIME}" \
    | sed 's/(uint32 \([0-9]\+\),)/\1/g' \
    > "${NOTIFICATION_ID_PATH}"
}

case "$1" in
  -inc)
    notify $(( ( $(brightnessctl --machine-readable | cut -d ',' -f3) + ${DELTA} * ${STEP}) * 100 / "${MAX}" )) &
    for i in $(seq "${STEP}"); do
      brightnessctl s "+${DELTA}" > /dev/null
    done
    [[ "$(brightnessctl --machine-readable | cut -d ',' -f3)" -gt "${MAX}" ]] && brightnessctl s "${MAX}"
    ;;
  -dec)
    notify $(( ( $(brightnessctl --machine-readable | cut -d ',' -f3) - ${DELTA} * ${STEP}) * 100 / "${MAX}" )) &
    [[ "$(brightnessctl --machine-readable | cut -d ',' -f3)" -gt "${MAX}" ]] && brightnessctl s "${MAX}"
    for i in $(seq "${STEP}"); do
      brightnessctl s "${DELTA}-" > /dev/null
    done
    ;;
  *)
    echo "Usage: backlit [-inc|-dec]" > /dev/stderr
    exit 1
    ;;
esac