Sunsetting XRandR Brightness

For a change, let’s talk about a topic other than notifications. More than five years ago (can’t believe how time has passed) I took over maintainership of PowerDevil, Plasma’s power management service. While I did a lot of cleanup and feature work in the beginning, there haven’t been many major changes for some time.

Bar-like popup informing of a screen brightness change
“Blast from the Past” – just casually sneaking in the more compact volume/brightness popup we’ll have in Plasma 5.20 to get your attention

One of the first features I added back then was smooth brightness changes. PowerDevil supports three ways of changing screen brightness: through XRandR configuration, through DDC (display data channel, for desktop monitors, experimental and not built by default), and by writing to sysfs (/sys/class/backlight or /sys/class/leds). Since the latter requires privileges and uses a helper binary through KDE’s KAuth framework, I only implemented the animation for the XRandR code path, which was executed in the same process.

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