#!/bin/bash

usage_exit () {
    local name="${0##*/}"
    echo "\
Usage: $name
       $name off
       $name 1.0
       $name 1.5
       $name 2.0"
    exit 1
}

if [[ -n "$2" ]]; then
    usage_exit
fi

scale_go () {
    local pointer_dev=$(xinput | sed -nr '/Virtual core/d;s/^.*id=([0-9]+).*slave +pointer.*$/\1/p')
    local output_dev=$(xrandr | sed -nr 's/^(.*) connected primary.*$/\1/p')
    for x in $output_dev; do
	xrandr --output $x --scale ${1}x${1}
    done
    for x in $pointer_dev ; do
	xinput set-prop $x 'Coordinate Transformation Matrix' ${1} 0 0 0 ${1} 0 0 0 1
    done
}

case "$1" in
    (off|1|1.0)
	scale_go 1 ;;
    (1.5)
	scale_go 1.5 ;;
    (2|2.0)
	scale_go 2 ;;
    (*)
	usage_exit ;;
esac