#!/bin/sh
#
# squeeze - squeeze an image using seam carving
#
# $Id$

# Some alpha composition is used to crop the result to the original size.
#
# Modified from the original at
#
#  http://www.imagemagick.org/Usage/resize/

# default values:

bc=black  # border color
bf=black  # border fill color
bw=1      # border size in pixels
td=42     # total duration in seconds
sw=1      # number of pixels to reduce by in each step
pg=1      # percentage to shrink image to

# overrides from the environment:

: ${bc=SQUEEZE_BORDER_COLOR}
: ${bf=SQUEEZE_BORDER_COLOR}
: ${bf=SQUEEZE_BORDER_FILL_COLOR}
: ${bw=SQUEEZE_BORDER_WIDTH}
: ${td=SQUEEZE_DURATION}
: ${sw=SQUEEZE_STEP_WIDTH}
: ${pg=SQUEEZE_PERCENTAGE}

AnimatedSeamCarve()
{
  {
    echo -delay $td "$1" -resize 50% -trim +repage -bordercolor $bc
    echo \( +clone -border ${bw}x${bw} -fill $bf -colorize 100% \)
    echo -gravity center

    for i in `seq 100 -$sw $pg ;`; do
      echo \( -clone 0 -liquid-rescale ${i}x${i}%\!
      echo -border ${bw}x${bw} -clone 1 +swap -composite \)
    done

    # remove source images
    echo  -delete 0,1

    # duplicate frames to reverse
    echo \( -clone -2-1 \)

    # write out animation
    echo -layers Optimize -loop 0 "$2"
  } |
  xargs convert
}

for f in "$@"
do
  AnimatedSeamCarve "$f" "$f".gif
done