remove_watermark

#! /bin/bash

# Remove "Solidworks Student Edition. For Academic Use Only" watermarks
# from your PDFs. Those can be annoying when they cover up your tables and
# stuff like that. Authors of technical drawings, even student authors,
# deserve full control over how their drawings are displayed.

# Copyright © 2014–2015 Repentinus <repentinus plus sw at fsfe dot org>

# Copying and distribution of this file, with or without modification,
# are permitted in any medium without royalty provided the copyright
# notice and this notice are preserved.  This file is offered as-is,
# without any warranty.


if [[ $# -lt 1 ]]; then
	echo 'Usage: remove_watermark file1 [file*]'
	exit 1
fi

for file in "$@"
do
	tmp=$(mktemp -t remove_watermark.$$.XXXXXXXXXX)
	e=$?
	tmp2=$(mktemp -t remove_watermark.$$.XXXXXXXXXX)
	let "e = $e + $?"
	if [[ e -ne 0 ]]; then
		echo "Failed to create temporary files."
		exit 2
	fi
	qpdf=$(qpdf --stream-data=uncompress "$file" $tmp)
	if [[ $? -ne 0 ]]; then
		echo "Failed to uncompress $file. Skipping…"
		echo $qpdf
		rm $tmp $tmp2
		continue
	else
		sed=$(sed -i 's/00360052004F004C0047003A00520055004E005600030036005700580047004800510057000300280047004C0057004C005200510011>Tj//g' $tmp && sed -i 's/<00030029005200550003002400460044004700480050004C00460003003800560048000300320051004F005C0011>Tj//g' $tmp)
		if [[ $? -ne 0 ]]; then
			echo "Watermark deletion for $file, $tmp failed. Skipping…"
			echo $sed
			rm $tmp $tmp2
			continue
		fi
		qpdf=$(qpdf --stream-data=compress $tmp $tmp2)
#		if [[ $? -ne 0 ]]; then
#			echo "Compression of $file, $tmp failed. Skipping…"
#			echo $qpdf
#			rm $tmp $tmp2
#			continue
#		else
		gs=$(gs -o $tmp -sDEVICE=pdfwrite -dPDFSETTINGS=/prepress $tmp2)
			mv $tmp "$file"
#		fi
	fi
done