initial commit

README.md

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+## blight
+
+A basic backlight utility using the logind SetBrightness method.
+
+Use '-d/--device' to select the target device. Otherwise picks a default.
+Use '+/-' to indicate relative changes and '%' to indicate fractional values.
+
+Set values:
+```
+$ blight set 300 # absolute 300
+$ blight set 50% # 50% of max
+$ blight set +5% # +5% of max
+$ blight set -- -10% # -10% of max
+$ blight set 100% # max brightness
+$ blight set 0 # minimum brightness
+```
+
+Get values:
+```
+$ blight get default-device
+backlight/intel_backlight
+$ blight -d leds/dell::kbd_backlight get max-brightness
+2
+```

blight.py

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+#!/usr/bin/python3
+
+import sys
+import gi
+gi.require_version("GUdev", "1.0")
+from gi.repository import GUdev, GLib, Gio
+
+import argparse
+
+def get_default_device():
+	gclient = GUdev.Client()
+	devices = gclient.query_by_subsystem("backlight")
+	devices = [ (dev.get_sysfs_attr("type"), dev) for dev in devices ]
+
+	# Prefer firmware
+	for devtype, dev in devices:
+		if devtype == "firmware":
+			return dev
+
+	# ... then platform
+	for devtype, dev in devices:
+		if devtype == "platform":
+			return dev
+
+	# ... then raw under enabled drm-connectors
+	for devtype, dev in devices:
+		if devtype == "raw":
+			parent = dev.get_parent()
+			enabled = parent.get_sysfs_attr("enabled")
+			if enabled == "enabled":
+				return dev
+
+	print(f"Cannot find a suitable backlight device", file = sys.stderr)
+	exit(1)
+
+def get_named_device(devname):
+	if '/' in devname:
+		try:
+			subsystem, name = devname.split('/')
+		except ValueError as e:
+			print(f"Invalid device name: {devname!r}")
+			exit(1)
+	else:
+		subsystem = 'backlight'
+		name = devname
+
+	gclient = GUdev.Client()
+	dev = gclient.query_by_subsystem_and_name(subsystem, name)
+	if dev:
+		return dev
+	else:
+		print(f"No such device: {devname!r}")
+		exit(1)
+
+def devname(dev):
+	subsystem = dev.get_subsystem()
+	name = dev.get_name()
+	return f"{subsystem}/{name}"
+
+def make_param(target, dev):
+	max_brightness = dev.get_sysfs_attr_as_int("max_brightness")
+	cur_brightness = dev.get_sysfs_attr_as_int("brightness")
+	percent = max_brightness / 100
+
+	if max_brightness < 99 and dev.get_sysfs_attr("type") == "raw":
+		min_brightness = 0
+	else:
+		min_brightness = 1
+
+	brightness = 0
+	if target.startswith('-') or target.startswith('+'):
+		brightness = cur_brightness
+
+	try:
+		if target.endswith('%'):
+			brightness += float(target[:-1]) * percent
+		else:
+			brightness += float(target)
+	except ValueError as e:
+		print(f"Invalid brightness value: {target!r}", file = sys.stderr)
+		exit(1)
+
+	if brightness < min_brightness:
+		brightness = min_brightness
+	if brightness > max_brightness:
+		brightness = max_brightness
+
+	return GLib.Variant(
+		'(ssu)',
+		[
+			dev.get_subsystem(),
+			dev.get_name(),
+			round(brightness),
+		]
+	)
+
+def set_brightness(target, dev = None):
+	if not dev:
+		dev = get_default_device()
+
+	method = [
+		'org.freedesktop.login1',
+		'/org/freedesktop/login1/session/self',
+		'org.freedesktop.login1.Session',
+		'SetBrightness'
+	]
+
+	param = make_param(target, dev)
+
+	bus = Gio.bus_get_sync(Gio.BusType.SYSTEM, None)
+	bus.call_sync(
+		*method, param, None,
+		Gio.DBusCallFlags.NONE, -1, None
+	)
+
+
+getters = {
+	'default-device': None, # Handled
+	'brightness': lambda dev: dev.get_sysfs_attr("brightness"),
+	'max-brightness': lambda dev: dev.get_sysfs_attr("max_brightness"),
+}
+
+def get_value(value, dev = None):
+	if value == "default-device":
+		dev = get_default_device()
+		return devname(dev)
+
+	if value == "help":
+		return list(getters)
+
+	if not dev:
+		dev = get_default_device()
+
+	if value in getters:
+		return getters[value](dev)
+	else:
+		print(f"Unknown query: {value!r}")
+		exit(1)
+
+if __name__ == "__main__":
+	parser = argparse.ArgumentParser(prog = "blight")
+	parser.add_argument('-d', '--device', help = "Which backlight device to modify")
+
+	subparsers = parser.add_subparsers(dest = "action", required = True)
+
+	parser_set = subparsers.add_parser("set", help = "Set a value")
+	parser_set.add_argument("value", help = "A brightness value.")
+
+	parser_get = subparsers.add_parser("get", help = "Get a value")
+	parser_get.add_argument("value", help = "Value to get")
+
+	args = parser.parse_args()
+	dev = get_named_device(args.device) if args.device else None
+
+	if args.action == "set":
+		set_brightness(args.value, dev = dev)
+	elif args.action == "get":
+		result = get_value(args.value, dev = dev)
+		if isinstance(result, list):
+			for item in result:
+				print(item)
+		else:
+			print(result)
+

completion/bash/blight

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+_blight() {
+	local cur=${COMP_WORDS[COMP_CWORD]} prev=${COMP_WORDS[COMP_CWORD-1]}
+	local -a OPTS=( -d --device )
+	local -a ARGS=( get set )
+
+	case $prev in 
+		--device|-d)
+			local -a devices=( /sys/class/{backlight,leds}/* )
+			COMPREPLY+=( ${devices[@]##/sys/class/} )
+			;;
+		get)
+			COMPREPLY+=( $(./blight.py get help 2>/dev/null) )
+			;;
+		*)
+			COMPREPLY+=( ${OPTS[@]} )
+			COMPREPLY+=( ${ARGS[@]} )
+			;;
+	esac
+}
+
+complete -F _blight blight

completion/zsh/_blight

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+#compdef blight
+
+__blight() {
+	blight "$@" 2>/dev/null
+}
+
+local -a getable=( ${(@f)"$(__blight get help)"} )
+
+_regex_arguments _blight_actions /$'[^\0]#\0'/ \
+	\( /$'set\0'/ :'compadd set' \| \
+	\( /$'get\0'/ :'compadd get' \
+	   /"(${(j.|.)getable})"$'\0'/ :'compadd -a getable' \) \
+	\)
+
+local -a devices=( /sys/class/*/*/brightness(N:h:t2) )
+_arguments -s -S \
+	{-d,--device=}'[Device to manipulate]:device:_multi_parts / devices' \
+	'*::action:= _blight_actions'