#!/bin/sh
#
# Set the pixel aspect ratio of one or more PNG files.
#

bye()
{
    rm -f $tmpppm $tmptxt
    exit $1
}

[ $# -lt 3 ] && { echo "usage: pngasp xunits yunits file ..." >&2; exit 1; }
xunits=$1; yunits=$2; shift 2

tmpppm=$(mktemp ~/.pngasp.XXXXXX) || bye 1
tmptxt=$(mktemp ~/.pngasp.XXXXXX) || bye 1
for f in "$@"; do
    pngtopnm -text $tmptxt "$f" >$tmpppm || bye 1
    txtopt=; [ -s $tmptxt ] && txtopt="-ztxt $tmptxt"
    pnmtopng -gamma 0.4545 -phys $xunits $yunits 0 $txtopt $tmpppm >"$f" || \
	bye 1
done
bye 0
.