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