wl-gammarelay

This utility was developed from gammastep, a fork of redshift as well as examples from wlroots.

It allows using keybindings to dynamically change the color temperature and software brightness.

This used to be possible using redshift using the -P -O <temp> flags, but since wayland requires the client to keep running, I developed this tool that spins up a daemon and can be controlled via unix domain socket.

The wl-gammarelay is a daemon which listens to DBus requests:

busctl --user -- call rs.wl-gammarelay / rs.wl.gammarelay UpdateTemperature n -500
busctl --user -- call rs.wl-gammarelay / rs.wl.gammarelay UpdateTemperature n +500

busctl --user -- call rs.wl-gammarelay / rs.wl.gammarelay UpdateBrightness d -0.2
busctl --user -- call rs.wl-gammarelay / rs.wl.gammarelay UpdateBrightness d +0.2

busctl --user -- set-property rs.wl-gammarelay / rs.wl.gammarelay Brightness d 0.5
busctl --user -- set-property rs.wl-gammarelay / rs.wl.gammarelay Brightness d 1

busctl --user -- set-property rs.wl-gammarelay / rs.wl.gammarelay Temperature q 4000
busctl --user -- set-property rs.wl-gammarelay / rs.wl.gammarelay Temperature q 6500

The service can be introspected:

$ busctl --user introspect rs.wl-gammarelay / rs.wl.gammarelay
NAME               TYPE      SIGNATURE RESULT/VALUE FLAGS
.UpdateBrightness  method    d         -            -
.UpdateTemperature method    n         -            -
.Brightness        property  d         1            emits-change writable
.Temperature       property  q         6500         emits-change writable

The UpdateBrightness and UpdateTemperature are here for relative adjustments.

Sample hotkey configuration for sway:

exec wl-gammarelay

bindsym $mod+Control+Minus      exec busctl --user -- call rs.wl-gammarelay / rs.wl.gammarelay UpdateTemperature n -100
bindsym $mod+Control+Equal      exec busctl --user -- call rs.wl-gammarelay / rs.wl.gammarelay UpdateTemperature n +100
bindsym $mod+Control+0          exec busctl --user set-property rs.wl-gammarelay / rs.wl.gammarelay Brightness d 1.0 && busctl --user set-property rs.wl-gammarelay / rs.wl.gammarelay Temperature q 6500
bindsym $mod+Control+Underscore exec busctl --user -- call rs.wl-gammarelay / rs.wl.gammarelay UpdateBrightness d -0.02
bindsym $mod+Control+Plus       exec busctl --user -- call rs.wl-gammarelay / rs.wl.gammarelay UpdateBrightness d +0.02

Sample configuration for waybar:

{
  "modules-right": ["custom/wl-gammarelay-temperature", "custom/wl-gammarelay-brightness"],
  "custom/wl-gammarelay-temperature": {
    "format": "{} ",
    "exec": "wl-gammarelay --subscribe Temperature",
    "on-scroll-up": "busctl --user -- call rs.wl-gammarelay / rs.wl.gammarelay UpdateTemperature n +100",
    "on-scroll-down": "busctl --user -- call rs.wl-gammarelay / rs.wl.gammarelay UpdateTemperature n -100"
  },
  "custom/wl-gammarelay-brightness": {
    "format": "{} ",
    "exec": "wl-gammarelay --subscribe Brightness",
    "on-scroll-up": "busctl --user -- call rs.wl-gammarelay / rs.wl.gammarelay UpdateBrightness d +0.02",
    "on-scroll-down": "busctl --user -- call rs.wl-gammarelay / rs.wl.gammarelay UpdateBrightness d -0.02"
  }
}

Tested on Arch Linux and Ubuntu 20.04 LTS using swaywm.

Installation

make
sudo make install

To install to /usr/bin set the PREFIX variable when running make:

sudo make install PREFIX=/usr

Arch Linux

This package is also on AUR: https://aur.archlinux.org/packages/wl-gammarelay/

Dependencies

• go 1.17
• wayland (libwayland-dev)