Bug 510361

Created attachment 185585 [details]
a-crude-mockup

SUMMARY

Add Night Brightness option (name up for debate)

The Idea is pretty much to do the same as done with night light, but with screen brightnesses. Have a system settings page to set it up in a similar manner and a system tray option to manually set the brightness to overwrite the upcoming transition or just a switch to suspend for the time being like the night light option. 

Plasma is uniquely positioned to add this feature, since no other desktop environment has something like this, AND most of the work is already done by other components throughout plasma, so it could be just a matter of puzzling the pieces together, for the most part.

Pieces to get this going (I try to list already existing solutions): 
1. The monitor selection UI from "Display & Monitor -> Display Configuration" (this should handle multi monitor cases)
2. The day/night switch logic in "Display & Monitor -> Night Light", here instead of color temperature have the brightness per monitor.
3.a) The system tray: the UI for Night Light switching is great, but I feel the brightness slider must remain in the tray for quick access. This will need a button to the page where the setup happens and a per screen switch for suspend. The button to the settings page and the text saying the transition times would only be needed once so they could be put at the bottom of the screen list (this would follow the night light ui at the moment)
3.b) Or a bit different solution to have a Night Brightness section, which would be the exact same like night light and control the whole ordeal, and setting the brightness manually would automatically suspend the transition/ lower night brightness (and the suspend switch would automatically turn on as well to have feedback to the user).
The evening transition text needs to be put under each display respectively (I don't have a good position for this), or just not have that line and have only the brightness slider go down as time goes by (Could the slider have an icon on it that indicates that it will be going until then? a sun and a moon icon perhaps)

Check out the attachment for a better idea of what I'm trying to say.

existing third party solution: https://github.com/digitaltrails/vdu_controls

considerations:
    - multiple monitors
    - manual brightness control
    - https://bugs.kde.org/show_bug.cgi?id=503268
    - how this will fit, if and when the above is implemented as well

This shouldn't be a duplicate, since most chatter is about auto brightness by a light sensor: 
https://bugs.kde.org/show_bug.cgi?id=502122
https://discuss.kde.org/t/does-kde-plasma-support-automatic-display-brightness-adjustment-on-desktops/6070/4

I feel this would be a very cool feature, espescially for desktops, for laptops the light sensor one is probably more useful.