monitor-switch

#!/bin/bash
#
# monitor-switch - switch outputs using xrand
#
#    Copyright (C) 2012 Rodrigo Silva (MestreLion) <linux@rodrigosilva.com>
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation, either version 3 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program. See <http://www.gnu.org/licenses/gpl.html>

# TODO: Allow multiple monitors on --select

declare -A monitor_opts
declare -a monitors

myname="${0##*/}"
verbose=0
debug=0
list=0
all=0
force=0
monitors=()
enable=()

print_monitors() {
	while read -r output conn hex; do
		echo "# $output	$conn	$(xxd -r -p <<< "${hex:-2d}")"
	done < <(LC_ALL=C xrandr --prop | tr -d '\r' | awk '
	h && /[^ \ta-f0-9]/ {
		n = split(hex, names, "000000fc00")
		hex = ""
		for (i = 2; i <= n; i++) {
			name = substr(names[i], 0, 26) "0a"
			sub(/0a.*/, "", name)
			if (name) {
				if (hex) name = "20" (name "")
				hex = hex (name "")
			}
		}
		h = 0
	}
	!/^[ \t]/ {
		if (ok) print output, conn, hex
		output = $1
		conn = output; sub(/-.*$/, "", conn)
		ok = (output && (substr($2, 0, 1) == "c"))  # Connected output
		hex = ""
		h = 0
	}
	h {sub(/[ \t]+/, ""); hex = hex ($0 "")}
	/EDID.*:/ {h=1; ok=(output && 1)}
	/ConnectorType:/ {conn = $2}
	END {if (ok) print output, conn, hex}
	' | sort)
}

inarray() {
	local i item=$1; shift;
	for i; do if [[ "$i" == "$item" ]]; then return 0; fi; done
	return 1
}

num2out() {
	if [[ -z "$1" ]]; then missing "" OUTPUT; fi
	if [[ "$1" != *[!0-9]* ]]; then
		if (($1 < 1 || $1 > ${#monitors[@]})); then
			argerr "invalid OUTPUT: $1"
		fi
		out=${monitors[$(($1-1))]}
	else
		out=$1
	fi
}

message() { printf "%s\n" "$1" >&2 ; }
fatal()   { [[ "${1:-}" ]] && echo -e "$myname: error: $@" >&2 ; exit 1; }
argerr()  { printf "%s: %s\n" "$myname" "${1:-error}" >&2 ; usage 1 ; }
invalid() { argerr "invalid argument: $1" ; }
missing() { argerr "missing ${2:+$2 }operand${1:+ from $1}." ; }

usage() {
	cat <<-USAGE
	Usage: $myname [options]
	USAGE
	if [[ "$1" ]] ; then
		cat >&2 <<- USAGE
		Try '$myname --help' for more information.
		USAGE
		exit 1
	fi
	cat <<-USAGE

	Switch monitors using xrandr.

	Options:
	  -h|--help          - show this page.
	  -v|--verbose       - print in terminal the full xrandr command executed.
	  -d|--debug         - print debugging information on --list. Implies --verbose.

	  -l|--list          - list connector and monitor names of connected outputs.
	                       When --verbose, also list the configured monitors.
	                       When --debug, also print the full unparsed output
	                       of 'xrand --prop' and the contents of the config file.

	  -a|--all           - enable all monitors.
	  -e|--enable OUTPUT - enable monitor OUTPUT. Can be specified multiple times.
	                       Monitors not enabled will be disabled.
	  -s|--select OUTPUT - enable monitor OUTPUT, disable all others.
	  -L|--left          - select leftmost monitor.  Alias for --select ${monitors[0]}
	  -R|--right         - select rightmost monitor. Alias for --select ${monitors[-1]}
	  -c|--center        - select center monitor.    Alias for --select ${monitors[1]}
	                       It actually just selects the second one, so this just makes
	                       sense in a 3-monitor setup.

	OUTPUT in --enable and --select can be either an output name, as given by --list,
	or the number of its position on the list, 1 being the first output.

	The left-to-right order of monitors can be specified in the configuration file:
	$config

	Copyright (C) 2012 Rodrigo Silva (MestreLion) <linux@rodrigosilva.com>
	License: GPLv3 or later. See <http://www.gnu.org/licenses/gpl.html>
	USAGE
	exit 0
}


# Read settings from config file
config=${XDG_CONFIG_HOME:-"$HOME"/.config}/"$myname".conf
if [[ -f "$config" ]]; then
	source "$config"
fi

# if there's no pre-defined monitors list, read from xrandr
# and save them to config file
if [[ -z "$monitors" ]]; then
	while read -r output ; do
		monitors+=("$output")
	done < <(xrandr | awk '$2 ~/^c/{print $1}' | sort)
	cat > "$config" <<-EOF
		# $myname config file

		# List of monitors, from left to right. Edit to your actual layout
		monitors=(${monitors[@]})

		# Extra xrandr options for each monitor.
		# Useful when EDID data does not reflect actual preferred mode
		# Options for non-existing outputs (such as the examples below) are ignored
		# Examples:
		#monitor_opts[DFPx]="--mode 1920x1080 --rate 60"
		#monitor_opts[DFPy]="--mode 1280x720"

		# As a reference, these were the connected monitors when this config file was created
		# use it as a guide when editing the above monitors list and extra options
		$(print_monitors)

		# For an updated list, run $myname --list
	EOF
fi

# Option handling
for arg in "$@"; do [[ "$arg" == "-h" || "$arg" == "--help" ]] && usage ; done
while (( $# )); do
	case "$1" in
	-v|--verbose) verbose=1 ;;
	-d|--debug) verbose=1; debug=1;;
	-q|--no-notify) notify=0;;  # undocumented. For future `notify-send`
	-l|--list) list=1 ;;
	-f|--force) force=1;;
	-s|--select) shift; num2out "$1"; enable=(  "$out" );;
	-e|--enable) shift; num2out "$1"; enable+=( "$out" );;
	-a|--all  )  enable=( "${monitors[@]}"  );;
	-L|--left )  enable=( "${monitors[0]}"  );;
	-R|--right)  enable=( "${monitors[-1]}" );;
	-c|--center) enable=( "${monitors[1]}"  );;
	*) invalid "$1" ;;
	esac
	shift
done

if ((list)); then
	echo "Connected monitors:"
	print_monitors
	if ((verbose)); then
		printf "\nConfigured monitors:\n"
		for output in "${monitors[@]}"; do
			echo -e "# ${output}${monitor_opts[$output]:+\t${monitor_opts[$output]}}"
		done
		printf "\nConfiguration file: %q\n" "$config"
	fi
	if ((debug)); then
		dashes=-----------------------------------------------------------------
		if [[ -f "$config" ]]; then
			printf '\nContents of configuration file:\n%s\n' "$dashes"
			cat "$config"
		else
			printf '\nNo configuration file found at %q\n' "$config"
		fi
		echo "$dashes"
		xrandr --prop
		echo "$dashes"
	fi
	exit
fi

if ! ((${#enable[@]})) && ! ((all)); then
	usage
fi

# Loop outputs (monitors)
previous=
for output in "${monitors[@]}"; do
	# Turn off monitors that were not chosen
	if ! inarray "$output" "${enable[@]}"; then
		xrandropts+=(--output "$output" --off)
		continue
	fi

	# Load custom settings for that monitor
	# monitor_opts is intentionally not quoted, to allow a single string
	# to contain multiple options
	xrandropts+=(--output "$output" --auto ${monitor_opts["$output"]})

	if [[ -z "$previous" ]]; then
		# Set first enabled monitor as primary
		xrandropts+=(--pos 0x0 --primary)
	else
		# And subsequent ones to the right
		xrandropts+=(--right-of "$previous")
	fi
	previous="$output"
done

if [[ -z "$previous" ]] && ! ((force)); then
	fatal "Your request will result in all monitors being disabled,\n"   \
	"check the configuration file at $config\n"                          \
	"and use --force to confirm. This is the resulting xrand command:\n" \
	"xrandr ${xrandropts[*]}"
fi
((verbose)) && message "$myname: executing xrandr ${xrandropts[*]}"
xrandr "${xrandropts[@]}"