dell_xps_15_brightness.py

#!/usr/bin/env python3

##
## Poll xrandr to find brightness of connected monitors, set if above threshold
##

##
## Place this file in /usr/bin/dell_xps_15_brightness, set it to executable, and link it:
## ln -s /usr/bin/dell_xps_15_brightness /lib/systemd/system-sleep
##
## On Wakeup, your system should fix your brightness to the threshold below.
##
import re, sys, os
import subprocess

import logging
import logging.handlers

search_string = r'^(?P<monitor>[a-zA-Z0-9\-]+).connected.*Brightness:.(?P<level>[\d.]+)$'
msearch = re.compile(search_string, flags = re.M | re.S | re.I)

threshold = 0.6

log = logging.getLogger(__name__)
log.setLevel(logging.DEBUG)

if __name__ == "__main__":
    if '-t' in sys.argv:
        buffer = open('delltest.txt','r').read()
        handler = logging.StreamHandler(sys.stdout)
    else:
        output = subprocess.run('/usr/bin/xrandr --verbose --current'.split(' '), capture_output=True)
        buffer = output.stdout.decode(encoding='ASCII')
        handler = logging.handlers.SysLogHandler(address = '/dev/log')
        pass

    formatter = logging.Formatter('%(module)s: %(message)s')
    handler.setFormatter(formatter)
    log.addHandler(handler)

    monitors = buffer.split('Screen')
    log.debug(f'Found {len(monitors)} displays.')

    for m in monitors:
        for name, value in msearch.findall(m):
            try:
                value = float(value)
            except:
                continue
            if value > threshold:
                print(f'{name} brightness is {value}, too high, lowering to {threshold}')
                subprocess.run(f'xrandr --output {name} --brightness {threshold}'.split(' '), capture_output=True)
                continue
            log.debug(f'Check display {name}, value within threshold: {value}.')
            continue
    pass