I have a three-monitor setup and the middle screen is an ultrawide. Sometimes that's just too many photons, so I want to have a mode where the side screens have their brightness dimmed after a few minutes of inactivity, but then return to full brightness when I move the mouse into them.

I'm not a KDE developer, but I was hoping I could do this with a Kwin script. I did figure out that workspace.activeScreen correctly tracks the screen (since my active screen follows mouse focus). And I am happy to modulate the brightness using xrandr. But problematically, I think there is no "activeDesktopChanged" signal to latch onto.

What's the recommended way of monitoring the activeScreen?

Thanks for any help!
-James

As far as I can tell, since workspace.activeScreen is a property, there should be an associated signal workspace.activeScreenChanged. That's supposed to be the philosophy according to the latest API I could find. Of course, the philosophy seems to change every five seconds with vast inconsistencies from minor version to minor version. Kudos.

For the sake of anyone reading this at some point in the future, here is the hack I used to solve my problem with a bash script:

Code: Select all

#!/bin/bash

WAIT=0.1
DELAY=1
LCOUNTER=1
RCOUNTER=1
highbright="0.9"
lowbright="0.4"
defaultbright="1.0"

SHORT=h:l:
LONG=high:,low:

trap "xrandr --output DP-2 --brightness $defaultbright; xrandr --output DP-0 --brightness $defaultbright; exit" SIGHUP SIGINT SIGTERM

PARSED=$(getopt --options $SHORT --longoptions $LONG --name "$0" -- "$@")

if [[ $? -ne 0 ]]; then
   # getopt was ****
   exit 2
fi

eval set -- "$PARSED"

#echo "$PARSED"

while true; do

   case "$1" in

      -h|--high)
         highbright="$2"
         shift 2
         ;;

      -l|--low)
         lowbright="$2"
         shift 2
         ;;

      --)
         shift
         break
         ;;

      *)
         echo "Invalid argument."
         exit 3
         ;;

   esac

done

while true; do

   sleep $WAIT
   eval $(xdotool getmouselocation --shell)

   if (( X < 2560 )); then

      if (( LCOUNTER > 0 )); then
#         echo "ON LEFT, first time: $highbright"
         xrandr --output DP-0 --brightness "$highbright"
      fi

      let LCOUNTER=-1
#      echo "ON LEFT"

   elif (( X > 6000 )); then

      if (( RCOUNTER > 0)); then
#         echo "ON RIGHT, first time: $highbright"
         xrandr --output DP-2 --brightness "$highbright"
      fi

      let RCOUNTER=-1
#      echo "ON RIGHT"

   fi

   let LCOUNTER=LCOUNTER+1
   let RCOUNTER=RCOUNTER+1         

   if (( LCOUNTER == DELAY )); then
#      echo "LEFT GOING OFF: $lowbright"
      xrandr --output DP-0 --brightness "$lowbright"
   fi

   if (( RCOUNTER == DELAY )); then
#      echo "RIGHT GOING OFF: $lowbright"
      xrandr --output DP-2 --brightness "$lowbright"
   fi

done