#!/bin/bash

# set system dpi to the minimal dpi among all connected monitors

MIN_DPI=99999999

# loop through all connected monitors line by line
while IFS= read -r LINE; do
    WIDTH_PX=$(echo $LINE | grep -oP '\d+(?=x\d+)')
    [ -z "$WIDTH_PX" ] && continue
    WIDTH_MM=$(echo $LINE | grep -oP '\d+(?=mm x)')
    # calculate dpi of the monitor
    DPI=$(bc <<< "$WIDTH_PX*25.4/$WIDTH_MM")
    # update min dpi
    if [ "$DPI" -lt "$MIN_DPI" ]; then
        MIN_DPI=$DPI
    fi
done <<< "$(xrandr | grep ' connected')"

# update dpi
echo setting dpi to $MIN_DPI
echo Xft.dpi: $MIN_DPI | xrdb -merge

nitrogen --restore