root / pkpgcounter / trunk / pkpgpdls / tiff.py @ 3474

Revision 3474, 2.8 kB (checked in by jerome, 13 years ago)

Changed copyright years.

  • Property svn:eol-style set to native
  • Property svn:keywords set to Author Date Id Revision
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1# -*- coding: utf-8 -*-
2#
3# pkpgcounter : a generic Page Description Language parser
4#
5# (c) 2003-2009 Jerome Alet <alet@librelogiciel.com>
6# This program is free software: you can redistribute it and/or modify
7# it under the terms of the GNU General Public License as published by
8# the Free Software Foundation, either version 3 of the License, or
9# (at your option) any later version.
10#
11# This program is distributed in the hope that it will be useful,
12# but WITHOUT ANY WARRANTY; without even the implied warranty of
13# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14# GNU General Public License for more details.
15#
16# You should have received a copy of the GNU General Public License
17# along with this program.  If not, see <http://www.gnu.org/licenses/>.
18#
19# $Id$
20#
21
22"""This modules implements a page counter for TIFF documents."""
23
24import sys
25import os
26import mmap
27from struct import unpack
28
29import pdlparser
30
31class Parser(pdlparser.PDLParser) :
32    """A parser for TIFF documents."""
33    totiffcommands = [ 'cp "%(infname)s" "%(outfname)s"' ]
34    required = [ "cp" ]
35    format = "TIFF"
36    def isValid(self) :
37        """Returns True if data is TIFF, else False."""
38        littleendian = (chr(0x49)*2) + chr(0x2a) + chr(0)
39        bigendian = (chr(0x4d)*2) + chr(0) + chr(0x2a)
40        if self.firstblock[:4] in (littleendian, bigendian) :
41            return True
42        else :
43            return False
44
45    def getJobSize(self) :
46        """Counts pages in a TIFF document.
47
48           Algorithm by Jerome Alet.
49
50           The documentation used for this was :
51
52           http://www.ee.cooper.edu/courses/course_pages/past_courses/EE458/TIFF/
53        """
54        infileno = self.infile.fileno()
55        minfile = mmap.mmap(infileno, os.fstat(infileno)[6], prot=mmap.PROT_READ, flags=mmap.MAP_SHARED)
56        pagecount = 0
57        littleendian = (chr(0x49)*2) + chr(0x2a) + chr(0)
58        bigendian = (chr(0x4d)*2) + chr(0) + chr(0x2a)
59        if minfile[:4] == littleendian :
60            integerbyteorder = "<I"
61            shortbyteorder = "<H"
62        elif minfile[:4] == bigendian :
63            integerbyteorder = ">I"
64            shortbyteorder = ">H"
65        else :
66            raise pdlparser.PDLParserError, "Unknown file endianness."
67        pos = 4
68        try :
69            try :
70                nextifdoffset = unpack(integerbyteorder, minfile[pos : pos + 4])[0]
71                while nextifdoffset :
72                    direntrycount = unpack(shortbyteorder, minfile[nextifdoffset : nextifdoffset + 2])[0]
73                    pos = nextifdoffset + 2 + (direntrycount * 12)
74                    nextifdoffset = unpack(integerbyteorder, minfile[pos : pos + 4])[0]
75                    pagecount += 1
76            except IndexError :
77                pass
78        finally :
79            minfile.close()
80        return pagecount
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