root / pkpgcounter / trunk / pkpgpdls / tiff.py @ 443

Revision 443, 3.0 kB (checked in by jerome, 16 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#! /usr/bin/env python
2# -*- coding: ISO-8859-15 -*-
3#
4# pkpgcounter : a generic Page Description Language parser
5#
6# (c) 2003, 2004, 2005, 2006, 2007 Jerome Alet <alet@librelogiciel.com>
7# This program is free software; you can redistribute it and/or modify
8# it under the terms of the GNU General Public License as published by
9# the Free Software Foundation; either version 2 of the License, or
10# (at your option) any later version.
11#
12# This program is distributed in the hope that it will be useful,
13# but WITHOUT ANY WARRANTY; without even the implied warranty of
14# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15# GNU General Public License for more details.
16#
17# You should have received a copy of the GNU General Public License
18# along with this program; if not, write to the Free Software
19# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
20#
21# $Id$
22#
23
24"""This modules implements a page counter for TIFF documents."""
25
26import sys
27import os
28import mmap
29from struct import unpack
30
31import pdlparser
32
33class Parser(pdlparser.PDLParser) :
34    """A parser for TIFF documents."""
35    totiffcommands = [ "cat >%(fname)s" ]
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            self.logdebug("DEBUG: Input file is in the TIFF format.")
42            return True
43        else :   
44            return False
45   
46    def getJobSize(self) :
47        """Counts pages in a TIFF document.
48       
49           Algorithm by Jerome Alet.
50           
51           The documentation used for this was :
52           
53           http://www.ee.cooper.edu/courses/course_pages/past_courses/EE458/TIFF/
54        """
55        infileno = self.infile.fileno()
56        minfile = mmap.mmap(infileno, os.fstat(infileno)[6], prot=mmap.PROT_READ, flags=mmap.MAP_SHARED)
57        pagecount = 0
58        littleendian = (chr(0x49)*2) + chr(0x2a) + chr(0)
59        bigendian = (chr(0x4d)*2) + chr(0) + chr(0x2a)
60        if minfile[:4] == littleendian :
61            integerbyteorder = "<I"
62            shortbyteorder = "<H"
63        elif minfile[:4] == bigendian :
64            integerbyteorder = ">I"
65            shortbyteorder = ">H"
66        else :   
67            raise pdlparser.PDLParserError, "Unknown file endianness."
68        pos = 4   
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        minfile.close()
79        return pagecount
80       
81if __name__ == "__main__" :   
82    pdlparser.test(Parser)
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