#!/bin/bash
#
# divide_chopper [options] input_image output_prefix
#
# Divide an image by row, and then each row by columns, saving as PNG.
# This calls on "divide_vert" script, and takes the same options.
#
#    -i            Ignore the uninteresting 'gaps' between the rows.
#    -b color      Use this color as background.
#    -f fuzz       percentage threshold for background match
#
# Images are saved using a filename of   "prefix_###_###.png"
# consisting of the given path/prefix followed by the three digit row
# and column divisions where the piece was extracted from
#
# Example...
#
#   convert label:'Goodbye\nCruel World' +set label text.png
#
#   divide_chopper  -i -b white   text.png  parts
#
#   mogrify -bordercolor white -border 2  parts_*.png
#   montage -label '%f' parts_*.png \
#           -background grey -geometry +2+2 show:
#
# In the above example the use of the background option "-b white" was
# vital so as to prevent the "divide_vert" script from considering letters
# such as 'd' 'b' and 'l' as being 'black' dividers.
#
# To separate letters more fully add a '-f 10%" option, or higher.
#
###
#
# A total rewrite of script by  Joshua McGee <joshuamcgee AT gmail.com>
#
# Anthony Thyssen      3 December 2010
#

PROGNAME=`type $0 | awk '{print $3}'`  # search for executable on path
PROGNAME=`basename $PROGNAME`          # base name of program

# Collect options to pass to "divide_vert" script

while [  $# -gt 0 ]; do
  case "$1" in
  -i)         args="${args:+"$args "}-i" ;;
  -b) shift;  args="${args:+"$args "}-b $1" ;;
  -f) shift;  args="${args:+"$args "}-f $1" ;;
  *)  break ;;                      # end of user options
  esac
  shift   # next option
done

infile="$1"
prefix="$2"  # the start prefix (or path) to output PNG images

tmpdir=`mktemp -d "${TMPDIR:-/tmp}/$PROGNAME-XXXXXXXXXX"` ||
  { echo >&2 "$PROGNAME: Unable to create temporary directory"; exit 10;}
trap 'rm -rf "$tmpdir"' 0   # remove when finished (on end or exit)
trap 'exit 2' 1 2 3 15


# Use the faster divide_vert_bg if background has been requested
divider="divide_vert"
if expr match "$args" '.*-b ' >/dev/null; then
  divider="divide_vert_bg"
fi

echo "doing row division"
$divider $args "$infile" "$tmpdir/%03d.mpc"

#convert $tmpdir/*.mpc -background red -splice 0x1+0+0 -append show:

for row in $tmpdir/*.mpc; do

  num=$(echo $row | sed 's/^.*\/\([0-9][0-9]*\)\.mpc$/\1/')
  echo "Column dividing row $num"

  convert $row -rotate 90 miff:- |
    $divider $args - miff:- |
      convert - -rotate -90 "${prefix}_${num}_%03d.png"

done
exit 0