ICC Color Brightness

use ICC color profiles to change the brightness of the display inspired by icc-brightness but more performant and does not produces ICC files in local directory

NOTE: currently only intel_backlight is used for backlight change

Installation

mkdir build && cd build
cmake ..
make install

Archlinux

• aur-package

Dependencies

colord
lcms2
easyloggingpp
# only for building
pkgconf
cmake

How it works

• uses inotify to watch for changes on the kernel backlight driver (currently only /sys/class/backlight/intel_backlight/brightness)
• if this file gets modified, it sends events and the changed content to the main programm
• the main programm then uses little-cms to create a color profile with the brightness from the file
• this profile then gets applied to the colord-daemon but the daemon needs a file to read from
• this file is a file only in memory, and only exist as long as the programm runs (it uses the syscall memfd_create)

Where it works

• should work on all linux-based systems using the colord-daemon for color management and a compositor (wayland or Xorg) which supports color-manaement (e.g. Gnome, KDE, etc)

Currently testet on

• Archlinux with Gnome

Compositor not working with

• Sway (no color-manaement supports, but could be in future)

Development

Todo

• add commandline interface
• add config file?
• improve structure
• improve readme

workarround for icc file

• for a icc profile (which is needed for a setting it system wide) a file need to be saved some ware -> read/write in the slow SSD
• as a work arround, 3 solutions:
  1. save the file in a tmpfs
  2. use a named pipe as a file, eg.:

  mkfifo my_pipe
  cat file > my_pipe
  echo my_pipe > new_file
  rm my_pipe

  3. (current approach) use a memfd (memfd_create) to simulate a file in a fd which is saved in ram an cleared, if reference is cleared

Filewatcher approach

• use inotify and conditional variables as notification system for file changes