source_monitor.sh

#!/bin/bash
#set -x
wait_ac_connect()
{
  while ! on_ac_power ; do : ; sleep 0.25 ; done && echo PLUGGED_IN
}

wait_ac_disconnect()
{
  while on_ac_power ; do : ; sleep 0.25 ; done && echo UNPLUGGED
}

change_brightness()
{
#  dbus-send --session --print-reply\
#    --dest=org.gnome.SettingsDaemon.Power\
#    /org/gnome/SettingsDaemon/Power \
#    org.gnome.SettingsDaemon.Power.Screen.SetPercentage uint32:"$1"
qdbus org.gnome.SettingsDaemon /org/gnome/SettingsDaemon/Power org.gnome.SettingsDaemon.Power.Screen.SetPercentage "$1"
}

get_brightness()
{
  qdbus org.gnome.SettingsDaemon \
        /org/gnome/SettingsDaemon/Power \
        org.gnome.SettingsDaemon.Power.Screen.GetPercentage
}



BAT_PERCENTAGE=50
AC_PERCENTAGE=90

while true
do

   if on_ac_power ; then
      wait_ac_disconnect
      AC_PERCENTAGE=$(($(get_brightness)+1))
      sleep 0.25
      change_brightness "$BAT_PERCENTAGE"
   else
      wait_ac_connect
      BAT_PERCENTAGE=$(($(get_brightness)+1))
      sleep 0.25
      change_brightness "$AC_PERCENTAGE"
   fi

sleep 0.25
done