OLED Brightness Daemon

README.md

OLED Brightness Daemon

I'm using this for my Razer Blade 17 Pro 2020 to keep the brightness slider in Ubuntu GNOME up to date with the actual brightness of the display.

It's not pretty but it works. Remember to add this to your startup (gnome-session-properties).

License

Licensed under MIT. Use however.

backlightd.py

#!/usr/bin/env python3
import os
import sys
import time
import subprocess

DISPLAY_NAME = "DP-2" # Run `xrandr` to see the active display
PATH_BACKLIGHT = "/sys/class/backlight/acpi_video0/actual_brightness"
MIN_BRIGHTNESS = 0.2 # Don't let people turn off the screen completely
DEFAULT_BRIGHTNESS = 0.5 # In case we cannot read the source file
POLLING_INTERVAL_SECONDS = 0.5

if not os.path.exists(PATH_BACKLIGHT):
    # We're on Intel Graphics. No need to run this monitor
    sys.stdout.write("Ignoring self because of non-NVIDIA Graphics\n")
    sys.exit()

def getBrightness():
    try:
        with open(PATH_BACKLIGHT) as file:
            value = file.read().strip()
        fraction = int(value) / 100
    except:
        sys.stderr.write("ERROR: Failed to read backlight value\n")
        fraction = DEFAULT_BRIGHTNESS
    return MIN_BRIGHTNESS if fraction < MIN_BRIGHTNESS else fraction

def setBrightness(value):
    subprocess.Popen(["xrandr", "--output", DISPLAY_NAME, "--brightness", str(value)],
        stdin =subprocess.DEVNULL,
        stdout=subprocess.DEVNULL,
        stderr=subprocess.DEVNULL,
        bufsize=0)

setBrightness(getBrightness())

while 1:
    time.sleep(POLLING_INTERVAL_SECONDS)
    setBrightness(getBrightness())