Synchronize the gamma values on Gnome by majority vote

syncgamma.py

#!/usr/bin/env python3
import dbus

bus = dbus.SessionBus()
proxy = bus.get_object('org.gnome.Mutter.DisplayConfig',
                       '/org/gnome/Mutter/DisplayConfig')
iface = dbus.Interface(proxy, dbus_interface='org.gnome.Mutter.DisplayConfig')

resources = iface.GetResources()
serial = resources[0]
outputs = resources[2]
gamma = []

if len(outputs) != 3:
	raise NotImplementedError('Can only handle 3 monitors')

for output in outputs:
	gamma.append(iface.GetCrtcGamma(serial, output[2]))

if gamma[1] == gamma[2]:
	correctGamma = gamma[1]
	crtcToFix = outputs[0][2]
elif gamma[0] == gamma[2]:
	correctGamma = gamma[0]
	crtcToFix = outputs[1][2]
elif  gamma[0] == gamma[1]:
	correctGamma = gamma[0]
	crtcToFix = outputs[2][2]

iface.SetCrtcGamma(serial, crtcToFix, correctGamma[0], correctGamma[1], correctGamma[2])