hs.brightness.ambient() is returning "-1" (an error)

[malob]

Today I tried using hs.brightness.ambient(), but I wasn't able to get in to return anything other than “-1”.

I have a 2017 13-inch MacBook Pro with Touch Bar running macOS Mojave (10.14.0) and it's not connected to an external display. I chatted with @matthewfallshaw who has a 2018 15-inch MacBook Pro running Mojave, and he's also experiencing the same issue, so it seems unlikely that my sensor is on the fritz or that it's a software issue unique to my machine.

[cmsj]

I wonder if newer MacBooks have a different underlying piece of hardware for getting ambient data.

We use the IOKit service AppleLMUController, but that is not present on touchbar macs and AFAIK there is no way to get the ambient light sensor values on those Macs, because it's all routed into the T chip :/

[latenitefilms]

@cmsj - Is this relevant?

pirate/mac-keyboard-brightness#1 (comment)

[malob]

@cmsj, I think you're right. I just did a little googling and found this post on the Apple Developer Forum which is pretty strong confirmation. It seems that there isn't any public API for getting data from this sensor on macOS (even the current API that HS is using isn't public actually).

I wonder if there are private APIs for this that someone has stumbled on. I haven't looked through the code, but there's a Dynamic Dark Mode app on GitHub that seems to be using the sensor (though maybe they are just querying screen brightness). I found it while working on a Spoon that provides the same functionality, which is how I came across this issue in the first place.

[Madd0g]

I saw this - https://github.com/insidegui/DarkModeBuddy

not sure if it's relevant..

[cmsj]

that seems very relevant, I think we can make that work. It's private API, so might break at any time, but it's not like the old ambient sensor code was particularly public/supported.