root / pkpgcounter / trunk / pkpgpdls / dvi.py @ 3488

Revision 3474, 2.6 kB (checked in by jerome, 16 years ago)

Changed copyright years.

  • Property svn:keywords set to Author Id Date Revision
Line 
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 DVI documents."""
23
24import sys
25import os
26import mmap
27from struct import unpack
28
29import pdlparser
30
31class Parser(pdlparser.PDLParser) :
32    """A parser for DVI documents."""
33    totiffcommands = [ 'dvips -q -o - "%(infname)s" | gs -sDEVICE=tiff24nc -dPARANOIDSAFER -dNOPAUSE -dBATCH -dQUIET -r"%(dpi)i" -sOutputFile="%(outfname)s" -' ]
34    required = [ "dvips", "gs" ]
35    format = "DVI"
36    def isValid(self) :
37        """Returns True if data is DVI, else False."""
38        try :
39            if (ord(self.firstblock[0]) == 0xf7) \
40                and (ord(self.lastblock[-1]) == 0xdf) :
41                return True
42            else :
43                return False
44        except IndexError :
45            return False
46
47    def getJobSize(self) :
48        """Counts pages in a DVI document.
49
50           Algorithm by Jerome Alet.
51
52           The documentation used for this was :
53
54           http://www.math.umd.edu/~asnowden/comp-cont/dvi.html
55        """
56        infileno = self.infile.fileno()
57        minfile = mmap.mmap(infileno, os.fstat(infileno)[6], prot=mmap.PROT_READ, flags=mmap.MAP_SHARED)
58        pagecount = 0
59        pos = -1
60        eofchar = chr(0xdf)
61        postchar = chr(0xf8)
62        try :
63            try :
64                while minfile[pos] == eofchar :
65                    pos -= 1
66                idbyte = minfile[pos]
67                if idbyte != minfile[1] :
68                    raise IndexError, "Invalid DVI file."
69                pos = unpack(">I", minfile[pos - 4:pos])[0]
70                if minfile[pos] != postchar :
71                    raise IndexError, "Invalid DVI file."
72                pagecount = unpack(">H", minfile[pos + 27: pos + 29])[0]
73            except IndexError : # EOF ?
74                pass
75        finally :
76            minfile.close() # reached EOF
77        return pagecount
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