Initial import

bin/imgresize.sh

@@ -0,0 +1,74 @@
+#!/bin/sh
+# env
+# Written in 2019 by Lucas
+# CC0 1.0 Universal/Public domain - No rights reserved
+#
+# To the extent possible under law, the author(s) have dedicated all
+# copyright and related and neighboring rights to this software to the
+# public domain worldwide. This software is distributed without any
+# warranty. You should have received a copy of the CC0 Public Domain
+# Dedication along with this software. If not, see
+# <http://creativecommons.org/publicdomain/zero/1.0/>.
+
+usage() {
+	cat - <<. >&2
+Usage:
+	${0##*/} size in-file out-file
+
+"size" is WxH or Wx or xH.
+.
+	exit 1
+}
+
+check_dimension_format() {
+	printf "%s\n" "$1" | grep -q "^[0-9]*x[0-9]*\$" \
+	    && [ "$1" != "x" ]
+}
+
+if [ $# -ne 3 ] || ! check_dimension_format "$1"; then
+	usage
+fi
+if [ -z "$2" ]; then
+	printf "%s: Input file name can't be empty.\n" \
+	    "${0##*/}" >&2
+	exit 1
+fi
+if [ -z "$3" ]; then
+	printf "%s: Output file name can't be empty.\n" \
+	    "${0##*/}" >&2
+	exit 1
+fi
+
+size=$1
+w=${size#x*}
+h=${size%*x}
+infile=$2
+outfile=$3
+
+inprog=
+case $infile in
+*.jpg | *.jpeg)
+	inprog=jpegtopnm
+	;;
+*.png)	inprog=pngtopam
+	;;
+*)	printf "%s: Unknown input format.\n" "${0##*/}" >&2
+	exit 1
+	;;
+esac
+
+outprog=
+case $outfile in
+*.jpg | *.jpeg)
+	outprog=pnmtojpeg
+	;;
+*.png)	outprog=pamtopng
+	;;
+*)	printf "%s: Unknown output format.\n" "${0##*/}" >&2
+	exit 1
+	;;
+esac
+
+"$inprog" <"$infile" \
+    | pamscale ${w:+-width "$w"} ${h:+-height "$h"} \
+    | "$outprog" >"$outfile"