Automatic-scaling setup for Ubuntu with dual monitor setup (hidpi + nonhidpi) : QHD+ 3200x1800 and a FullHD 1920x1080

gistfile1.txt

The script:

#!/bin/bash

# eDP-1 connected primary 3200x1800+320+2160 (normal left inverted right x axis y axis) 294mm x 165mm
# DP-1 connected 3840x2160+0+0 (normal left inverted right x axis y axis) 521mm x 293mm

xhost +
export DISPLAY=:1
export XAUTHORITY=$(ps -C Xorg -f --no-header | sed -n 's/.*-auth //; s/ -[^ ].*//; p' | tail -1)

function dp_connected() {
  if xrandr | grep -w connected | awk {'print $1'} | grep -w "$1" >/dev/null ; then
    echo "true"
  else
    echo "false"
  fi
}

edp1_connected=$(dp_connected eDP1)
dp1_connected=$(dp_connected DP1)
echo "eDP1 connected $edp1_connected"
echo "DP1 connected $dp1_connected"

xrandr_command="xrandr --output 'eDP1' --auto --pos 320x2160 --panning 3200x1800+320+2160 --scale 1x1" 
if [[ "$dp1_connected" == "true" ]];then
  echo "DP1 connected"
  xrandr_command="$xrandr_command --output 'DP1' --auto --scale 2x2 --pos 0x0 --panning 3840x2160+0+0"
fi
echo "Xrandr command: $xrandr_command"
eval $xrandr_command
#ALTERNATIVE CRTC (changed in kernel 4.15 or so) xrandr --output "eDP-1" --auto --pos 320x2160 --panning 3200x1800+320+2160 --scale 1x1 --output "DP-1" --auto --scale 2x2 --pos 0x0 --panning 3840x2160+0+0

Plug the script into udev so everytime you connect/disconnect USBc-hdmi converter, the script will rearrange the screens so you get proper font sizes et al:

ACTION=="change", SUBSYSTEM=="drm", RUN+="/home/wojtek/bin/xrandr.bash"

Drop the script into /etc/udev/rules.d/fullhd-hidpi-monitor.rules