#!/bin/sh
#
# flicker_cmp [options] image1 image2 ...
#
# Generate and display an animation of the images given with 1/2 second delay
# so that you can see and compare the very slight differences between the two
# images.  A label is added to the image so you know which image is which.
#
# OPTIONS
#    -d delay    the delay for each frame in centi-seconds (def = 50)
#    -l label    Set label handling to this. EG: '%l' or '%s'  (def = '%f')
#    -r size     resize image to this size (pixels or percentage)
#    -s size     scale image to this size (pixels or percentage)
#
#
#
# Advanced example of labeling using a property setting.
#
# convert -size 100x100 xc:red xc:blue -set color '%[pixel:u]' miff:- |\
#     flicker_cmp -l '%[color]' -d 100 -
#
###
#
# Anthony Thyssen   5 September 2007
#
PROGNAME=`type $0 | awk '{print $3}'`  # search for executable on path
PROGDIR=`dirname $PROGNAME`            # extract directory of program
PROGNAME=`basename $PROGNAME`          # base name of program
Usage() {                              # output the script comments as docs
  echo >&2 "$PROGNAME:" "$@"
  sed >&2 -n '/^###/q; /^#/!q; s/^#//; s/^ //; 3s/^/Usage: /; 2,$ p' \
          "$PROGDIR/$PROGNAME"
  exit 10;
}

resize=''
delay=50

while [  $# -gt 0 ]; do
  case "$1" in
  --help|--doc*) Usage ;;

  -d|-delay)  shift; delay="$1" ;;          # animation delay
  -l|-label)  shift; label="$1" ;;          # set displayed label to this string
  -r|-resize) shift; resize="-resize $1" ;; # resize image to this size
  -s|-scale)  shift; resize="-scale $1" ;;  # scale image to this size

  -)  break ;;           # STDIN,  end of user options
  --) shift; break ;;    # end of user options
  -*) Usage "Unknown option \"$1\"" ;;
  *)  break ;;           # end of user options

  esac
  shift   # next option
done

# set labeling defaults, different for stdin vs filenames
if [ "X$label" = "X" ]; then
  case "$*" in
    -|*:-) label='%s:%l' ;;
    *)     label='%f' ;;
  esac
fi

convert "$@" -set label "$label" $resize miff:- |\
  montage - -geometry +0+0 -tile 1x1 -background white miff:- |\
    animate -delay "$delay" -dispose background -loop 0 -