nsbin/cbacklight

#!/usr/bin/python3
# Nico Schottelius
# 2018-03-30
# Copying: GPLv3
#
#
# Set / increase brightness to sysfs directly
#

import glob
import os
import argparse
import re
import sys

class BackLight(object):
    basepath="/sys/class/backlight/"

    def __init__(self, name):
        self.name = name
        self.dirname = os.path.join(self.basepath, name)
        self.brightness_file = os.path.join(self.dirname, "brightness")
        self.max_brightness_file = os.path.join(self.dirname, "max_brightness")

    @staticmethod
    def read_value(filename):
        with open(filename, "r") as fd:
            val = int("".join(fd.readlines()))
        return val

    @staticmethod
    def write_value(filename, value):
        try:
            with open(filename, "w") as fd:
                fd.write(str(value))
        except PermissionError as e:
            print("Cannot write to {}: {}".format(filename, e))
            sys.exit(1)

    @classmethod
    def get_dirs(cls):
        return glob.glob("{}*".format(cls.basepath))

    @classmethod
    def get_driver_from_dir(cls, directory):
        regexp = r"{}(?P<driver>.+)".format(cls.basepath)
        return re.match(regexp, directory).groupdict()['driver']

    @classmethod
    def get_drivers(cls):
        return [ cls(cls.get_driver_from_dir(x)) for x in cls.get_dirs() ]

    def get_value(self):
        return self.read_value(self.brightness_file)

    def get_max_value(self):
        return self.read_value(self.max_brightness_file)

    def get_percentage(self):
        val = self.get_value()
        maxval = self.get_max_value()

        percent = (val/maxval)*100

        return percent

    def get_percentage_points(self, percent):
        """Return integer equivalent to percent"""
        points = int((percent * self.get_max_value()) / 100)

        return points

    def inc_percent(self, percent):
        points = self.get_percentage_points(percent)
        new_value = self.get_value() + points
        self.set_value(new_value)

    def dec_percent(self, percent):
        points = self.get_percentage_points(percent)
        new_value = self.get_value() - points
        self.set_value(new_value)

    def set_percent(self, percent):
        new_value = int((percent * self.get_max_value()) / 100)

        self.set_value(new_value)

    def set_value(self, value):
        if value < 0:
            value = 0
        if value > self.get_max_value():
            value = self.get_max_value()

        self.write_value(self.brightness_file, value)

    def is_readable(self):
        return os.access(self.max_brightness_file, os.R_OK)

    def __str__(self):
        return self.name

if __name__ == '__main__':
    parser = argparse.ArgumentParser(description='cbacklight')
    group = parser.add_mutually_exclusive_group()

    group.add_argument('--inc', help='Increment by percentage (points)')
    group.add_argument('--dec', help='Decrement by percentage (points)')
    group.add_argument('--set', help='Set to percentage')

    parser.add_argument('--get', help='Get percentage (default)', action='store_true')

    args = parser.parse_args()

    anyarg = args.inc or args.dec or args.set

    drivers = BackLight.get_drivers()

    method = None
    if args.inc:
        method = "inc_percent"
        val    = args.inc
    if args.dec:
        method = "dec_percent"
        val    = args.dec
    if args.set:
        method = "set_percent"
        val    = args.set

    if method:
        for d in drivers:
            func = getattr(d, method)
            func(int(val))


    if not anyarg or args.get:
        for d in drivers:
            print("{}: {:.2f}%".format(d, d.get_percentage()))