Add brightness correction for OS X 10.15 Catalina

Since upgrading to 10.15 Catalina, when my external monitor is plugged
in and I wake up my machine, for some unexplained reason the internal
display resets to maximum brightness. Fix Catalina's nonsense on wake by
resetting to the brightness from before sleep.

1 files changed, 47 insertions, 0 deletions

diff --git a/catalina_brightness_bullshit.lua b/catalina_brightness_bullshit.lua
new file mode 100644
index 0000000..17d5bde
--- /dev/null
+++ b/catalina_brightness_bullshit.lua
@@ -0,0 +1,47 @@
+-- When an external monitor is connected, saves internal screen brightness when
+-- locking the screen or sleeping. Restores the saved brightness level on
+-- unlock or wake. Fixes OS X 10.15 Catalina's bullshit where unlocking my
+-- machine caused the internal screen's brightness to be reset to the maximum.
+
+-- Copyright (c) 2019  Teddy Wing
+--
+-- This program is free software: you can redistribute it and/or modify
+-- it under the terms of the GNU General Public License as published by
+-- the Free Software Foundation, either version 3 of the License, or
+-- (at your option) any later version.
+--
+-- This program is distributed in the hope that it will be useful,
+-- but WITHOUT ANY WARRANTY; without even the implied warranty of
+-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+-- GNU General Public License for more details.
+--
+-- You should have received a copy of the GNU General Public License
+-- along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+
+-- Default brightness to 50%.
+cbb_brightness = 50
+
+cbb_logger = hs.logger.new('catalina_brightness_bullshit', 'debug')
+
+cbb_wake_watcher = hs.caffeinate.watcher.new(function(event_type)
+	-- Only run if the external monitor is connected.
+	if hs.screen.primaryScreen():name() ~= 'G247HL' then
+		cbb_logger:d('no external monitor')
+
+		return
+	end
+
+	if event_type == hs.caffeinate.watcher.screensDidLock
+			or event_type == hs.caffeinate.watcher.screensDidSleep then
+		cbb_brightness = hs.brightness.get()
+
+		cbb_logger:d('saved brightness: ', cbb_brightness)
+	elseif event_type == hs.caffeinate.watcher.screensDidUnlock
+			or event_type == hs.caffeinate.watcher.screensDidWake then
+		hs.brightness.set(cbb_brightness)
+
+		cbb_logger:d('restored brightness: ', cbb_brightness)
+	end
+end)
+cbb_wake_watcher:start()