#!/bin/sh

# a small script to generate smaller images
# mainly used to generate thumbnails
# requires decent pnmtools installed
# (c) 1999-2000 by Yves Lafon / W3C - ylafon@w3.org
# Sat Jan 29 00:53:52 MET 2000
# 	       better use of pnmsmooth
# Change: Thu Jan  4 00:29:53 MET 2001 added -png
# Change: Thu Apr  7 16:08:29 CEST 2005 added -sq
#	  to create square icons by cropping the middle of the image.
# $Id: anytothumb,v 1.2 2005/04/07 14:10:06 ylafon Exp $


if [ $# = 0 ]; then
        echo "Usage: `basename $0` [-h][-sq][-png][-size <size>][-x][-y] <file>" 1>&2
        exit 1
fi

doHelp() {
    echo "Usage:"
    echo "     -h   : display help"
    echo "     -size: specify the thumbnail maximum size in pixel of the longest edge (default 100px)"
    echo "     -x   : the above size is used only for the horizontal size"
    echo "     -y   : the above size is used only for the vertical size"
    echo "     -sq  : create a square thumbnail by cropping the middle of the original image"
    echo "     -png : use PNG for the output"
    echo
    echo "if -x and -y are used, then the size will apply to the "
    echo "longest edge, like if they were not defined"
}

size=100
x=0
y=0
use_png=0
sq=0
smooth_threshold=3
for arg do
	case "$1" in
		"-size" ) shift; size=$1; shift;;
		"-x" ) x=1; shift;;
		"-y" ) y=1; shift;;
		"-png") use_png=1; shift;;
		"-sq") sq=1; shift;;
		"-h") doHelp ; exit 1 ;;
		"*" ) break
	esac
done

cut_cmd="cat"

if [ $use_png -eq 1 ]; then
    pre_cmd="cat"
    out_cmd="pnmtopng -downscale -compression 9"
else
    pre_cmd="ppmquant -fs 256"
    out_cmd="ppmtogif"
fi

file_type=`file "$1" | awk '{print $2}'`

case "$file_type" in
	"JPEG" )
        info_cmd="djpeg -pnm"
        trans_cmd="djpeg -pnm -dct float"
	;;
	"GIF" )
        info_cmd=giftopnm
        trans_cmd=giftopnm
	;;
	* )
	ext=`echo "$1" | sed 's/.*\.//g' | tr '[A-Z]' '[a-z]'`
	case "$ext" in
	    "jpg" | "jpeg" )
		info_cmd="djpeg -pnm"
		trans_cmd="djpeg -pnm -dct float"
	    ;;
	    "gif" )
		info_cmd=giftopnm
		trans_cmd=giftopnm
	    ;;
	    *)
	    info_cmd=anytopnm
	    trans_cmd=anytopnm
	    ;;
	esac
esac

# get the size info
raw_info=`$info_cmd "$1" | pnmfile `
x_size=`echo $raw_info | awk '{print $4}'`
y_size=`echo $raw_info | awk '{print $6}'`

if [ $sq -eq 1 ]; then
    if [ $x_size -gt $y_size ]; then
	start_x=`expr \( $x_size - $y_size \) / 2`
	start_y=0
	width_xy=$y_size
    else
	start_x=0
	start_y=`expr \( $y_size - $x_size \) / 2`
	width_xy=$x_size
    fi
    cut_cmd="pnmcut -left=${start_x} -top=${start_y} -width=${width_xy} -height=${width_xy}"
    x_size=$width_xy
    y_size=$width_xy
fi

# transform and generate the small gif

case "$size" in
        *x* )
	x_nsize=`echo $size | sed 's/x.*//'`
	y_nsize=`echo $size | sed 's/.*x//'`
	scale_cmd="-xsize $x_nsize -ysize $y_nsize"
	x_factor=`expr $x_size / $x_nsize`
	y_factor=`expr $y_size / $y_nsize`
	ix_factor=`expr $x_nsize / $x_size`
	iy_factor=`expr $y_nsize / $y_size`
	;;
        * )
	x_factor=0
	y_factor=0
	ix_factor=0
	iy_factor=0
	if [ $x = $y ]; then
	        if [ $x_size -gt $y_size ]; then
		        scale_cmd="-xsize $size"
			x_factor=`expr $x_size / $size`
			ix_factor=`expr $size / $x_size`
	        else
		        scale_cmd="-ysize $size"
			y_factor=`expr $y_size / $size`
			iy_factor=`expr $size / $y_size`
	        fi
        elif [ $x = 1 ]; then
	        scale_cmd="-xsize $size"
			x_factor=`expr $x_size / $size`
			ix_factor=`expr $size / $x_size`
        elif [ $y = 1 ]; then
	        scale_cmd="-ysize $size"
		y_factor=`expr $y_size / $size`
		iy_factor=`expr $size / $y_size`
        fi
esac

if [ $x_factor -ge $smooth_threshold -o $y_factor -ge $smooth_threshold ]; then
	$trans_cmd "$1" 2>/dev/null | $cut_cmd 2> /dev/null | pnmsmooth 2>/dev/null | pnmscale $scale_cmd 2>/dev/null | $pre_cmd 2> /dev/null | $out_cmd 2>/dev/null
elif [ $ix_factor -ge $smooth_threshold -o $iy_factor -ge $smooth_threshold ]; then
	$trans_cmd "$1" 2>/dev/null | $cut_cmd 2> /dev/null | pnmscale $scale_cmd 2>/dev/null | pnmsmooth 2>/dev/null | $pre_cmd 2> /dev/null | $out_cmd 2>/dev/null
else
	$trans_cmd "$1" 2>/dev/null | $cut_cmd 2> /dev/null | pnmscale $scale_cmd 2>/dev/null | $pre_cmd 2> /dev/null | $out_cmd 2>/dev/null
fi