window-trans

#!/bin/sh
help() {
  parens=
  if [ "${transset##*/}" != "transset" ]; then
    if [ -x "$transset" ]
      then parens=" ($transset)"
      else parens=' (though x11-apps is not installed)'
    fi
  fi
  cat <</help
Usage: window-trans [OPTIONS] [OPACITY]
Set a window's transparency; wraps transset$parens with a better --toggle

  --display=DISPLAY   Use this X11 server (same as \$DISPLAY, default=:0)
  -t, --toggle        Toggle opacity (CHANGED! detail at --toggle-help)
  -T, --toggle=up     Like toggle, but upgrade opacity >= 0.999 to 1
  --toggle-help       Explain how toggling works in this wrapper
  -c, --click         Select a window to modify by clicking on it (default)
  -p, --point         Select the window currently under the mouse cursor
  -a, --actual        Select the active window (use focus)
  -n, --name=NAME     Select a window by regular expression
  -R, --no-regex      If selecting by window name, match by exact string
  -i, --id=ID         Select the window with the given ID
  --dec, --inc        Decrement/Increment the window by OPACITY, not *to* it
  -m, --min=MINIMUM   Do not set the window opacity below MINIMUM opacity
  -x, --max=MAXIMUM   Do not set the window opacity above MAXIMUM opacity
  -X, --exe=TRANSSET  Run TRANSSET instead of $transset
  -v, --verbose       Print some debug info

A part of misc-scripts, https://github.com/adamhotep/misc-scripts
/help
  version
}
version() { cat <</version
window-trans 0.2.20210109.1 copyright 2021+ by Adam Katz, Apache License 2.0
/version
  if [ -x "$transset" ]; then
    "$transset" --version 2>&1 |awk '{printf s "%s", $0; s=" "} END {print ""}'
  fi
}

toggle_help() { cat <</toggle_help
Opacity is stored as a decimal from 0-1 in millionths, such as 0.987654.

This improved --toggle instead uses this as X.YYYZZZ as follows:
 * opacity is rounded to the thousandths (even outside of toggling)
 * --inc & --dec and --max & --min are adjusted to retain saved toggle values
 * if the current opacity is 1.000000 or 0.999999, it's treated as 0.999250
 * if the current opacity is above 0.979 and ZZZ==000, ZZZ is 250
 * if the current opacity is under 0.980 and ZZZ==000, ZZZ is 999
 * if given an OPACITY, set YYY to it and save the original (as 1000-YYY) in ZZZ
 * if not given an OPACITY, swap the current (YYY) and saved (ZZZ) opacities
/toggle_help
}

die() { printf '%s\n' "$@" >&2; exit 2; }  # complain to STDERR & exit w/ error

# Usage: safe_value VALUE PRINTF_FORMAT
safe_value() {
  : "making $1 safe"
  case "$1" in
    ( '' )				die "missing value" ;;
    ( . | *.*.* | *[^0-9.]* )		die "invalid number: $1" ;;
    ( [2-9]* | 1[0-9]* | 1.*[^0]* )	die "number exceeds 0-1 range" ;;
    ( * )				printf "${2:-%.3f}" "$1" ;;
  esac
}

needs_arg() { if [ -z "$OPTARG" ]; then die "No arg for --$OPT option"; fi; }

transset="$(command -v transset 2>/dev/null || command -v transset-df \
 || echo '<transset is not installed>')"
disp= toggle= toggle_opt= click= point= actual= name= no_regex= id=
inc= dec= verbose= min= max=
while getopts hd:tTcpan:Ri:m:x:X:vV-: OPT; do
  if [ "$OPT" = - ]; then # long opt https://stackoverflow.com/a/28466267/519360
    OPT="${OPTARG%%=*}" OPTARG="${OPTARG#"$OPT"}" OPTARG="${OPTARG#=}"
  fi
  case "$OPT" in
    ( h | help )	help; exit ;;
    ( d )		if [ "$OPTARG" = isplay ]  # legacy -display blah
    			  then die 'Use `--display=DISPLAY` or `-d DISPLAY`'
    			elif [ "$OPTARG" != "${OPTARG#isplay=}" ]
    			  then disp="${OPTARG#*=}" # ~legacy -display=blah
    			  else disp="$OPTARG"
    			fi ;;
    ( display ) 	needs_arg; disp="$OPTARG" ;;
    ( tog*help )	toggle_help; exit ;;
    ( T | tog*up* )	toggle=--toggle; toggle_opt="up" ;;
    ( t | tog* )	toggle=--toggle; toggle_opt="$OPTARG" ;;
    ( c | click )	click=--click ;;
    ( p | point* )	point=--point ;;
    ( a | act* )	actual=--actual ;;
    ( n | name* )	needs_arg; name="$OPTARG" ;;
    ( R | no*regex* )	no_regex=--no-regex ;;
    ( i | id* ) 	needs_arg; id="$OPTARG" ;;
    ( inc* )		inc=--inc dec= ;;
    ( dec* )		dec=--inc inc= ;;
    ( m | min* )	needs_arg; min="$(safe_value "$OPTARG")" ;;
    ( x | max* )	needs_arg; max="$(safe_value "$OPTARG")" ;;
    ( X | exe* )	needs_arg; transset="$OPTARG" ;;
    ( v | verb* )	verbose=--verbose ;;
    ( V | ver* )	version; exit ;;
    ( ??* )		die "Illegal option --$OPT" ;; # bad long option
    ( ? )		exit 2 ;; # bad short option (error via getopts)
  esac
done
shift $((OPTIND-1))

target="$1"	# the only argument left should be the (optional) target opacity

if ! [ -x "$transset" ]; then
  die "Could not find transset at \`$transset\`. Is it installed?"
fi

if [ -n "$min" ]; then
  min="--min=$min"
fi
if [ -n "$max" ]; then
  if [ "$max" = 1.000 ]; then
    max=0.999
  fi
  max="--max=$max"
fi

# this intentionally omits dec inc and target
set -- "$transset" ${disp:+-display "$disp"} $click $point $actual \
       ${name:+--name "$name"} $no_regex ${id:+--id "$id"} $verbose \

# get the current opacity, from 0.000000 to 1.000000
opacity=$( "$@" --verbose --inc 0 \
  |awk '$1$2$3 == "SetPropertyto" { printf "%.6f", $4; exit }'
)
current=${opacity#0.}
case $opacity in
  ( 0.*000 )	fsaved=999 current=${current%???} ;;
  ( 0.* )	fsaved=${current#???} current=${current%???} ;;
  ( * ) 	opacity=0.999250 current=999 fsaved=250 ;;
esac

flip() { printf %03d $((1000 - ${1#0})); }

saved=$(flip $fsaved)

# $opacity remains the full current opacity, 0.000000-0.999999
#          (if $opacity was 1.000000, it is now 0.999250, saving a 0.750)
# $current now holds the current opacity, 000-999 for 0.000-0.999 (1.000 -> 999)
# $fsaved  now holds the flipped saved opacity, 999-000 for 0.999-0.000
# $saved   now holds the saved opacity, 000-999 for 0.000-0.999

if [ $saved = $current ]; then
  : '$saved == $current, replacing $saved with a sensible default'
  case $current in
    ( 9[89]? )	saved=750 fsaved=250 ;;  # very highly opaque: 0.750
    ( * )	saved=999 fsaved=001 ;;  # a bit transparent:  0.999
  esac
fi

if [ -n "$target" ]; then
  target=$(safe_value "$target")
  if [ $target = 1.000 ]; then
    target=0.999
  fi
else	# no target means toggle
  toggle=--toggle
fi

: current="$current" saved="$saved" target="$target"

if [ -z "$toggle" ]; then	# $target is guaranteed here
  if [ -z "$inc$dec" ]; then
    target=$target$fsaved
  fi

  # alter min and max to force retaining the flipped_saved value at its end
  if [ -n "$min" ]; then
    set -- "$@" $min$fsaved
  fi
  if [ -n "$max" ]; then
    set -- "$@" $max$fsaved
  fi

  exec "$@" $inc $dec $target
  exit $?
fi


######## TOGGLE MODE ########

fcurrent=$(flip $current)

# alter min and max to force retaining the flipped_current value at its end
if [ -n "$min" ]; then
  set -- "$@" $min$fcurrent
fi
if [ -n "$max" ]; then
  if [ $max = 1.000 ]; then max=0.999; fi
  set -- "$@" $max$fcurrent
fi

if [ -n "$target" ]; then
  target=$target$fcurrent

elif [ "$toggle_opt" = "up" ] && [ $saved = 999 ]; then
  target=1

else
  : no target, swap with saved value
  target=0.$saved$fcurrent
fi

exec "$@" $target