1 | # -*- coding: utf-8 -*- |
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2 | # |
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3 | # pkpgcounter : a generic Page Description Language parser |
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4 | # |
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5 | # (c) 2003, 2004, 2005, 2006, 2007, 2008 Jerome Alet <alet@librelogiciel.com> |
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6 | # This program is free software: you can redistribute it and/or modify |
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7 | # it under the terms of the GNU General Public License as published by |
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8 | # the Free Software Foundation, either version 3 of the License, or |
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9 | # (at your option) any later version. |
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10 | # |
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11 | # This program is distributed in the hope that it will be useful, |
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12 | # but WITHOUT ANY WARRANTY; without even the implied warranty of |
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13 | # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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14 | # GNU General Public License for more details. |
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15 | # |
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16 | # You should have received a copy of the GNU General Public License |
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17 | # along with this program. If not, see <http://www.gnu.org/licenses/>. |
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18 | # |
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19 | # $Id$ |
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20 | # |
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21 | |
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22 | """This modules implements a page counter for DVI documents.""" |
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23 | |
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24 | import sys |
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25 | import os |
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26 | import mmap |
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27 | from struct import unpack |
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28 | |
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29 | import pdlparser |
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30 | |
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31 | class Parser(pdlparser.PDLParser) : |
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32 | """A parser for DVI documents.""" |
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33 | totiffcommands = [ 'dvips -q -o - "%(infname)s" | gs -sDEVICE=tiff24nc -dPARANOIDSAFER -dNOPAUSE -dBATCH -dQUIET -r"%(dpi)i" -sOutputFile="%(outfname)s" -' ] |
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34 | required = [ "dvips", "gs" ] |
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35 | format = "DVI" |
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36 | def isValid(self) : |
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37 | """Returns True if data is DVI, else False.""" |
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38 | try : |
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39 | if (ord(self.firstblock[0]) == 0xf7) \ |
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40 | and (ord(self.lastblock[-1]) == 0xdf) : |
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41 | return True |
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42 | else : |
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43 | return False |
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44 | except IndexError : |
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45 | return False |
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46 | |
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47 | def getJobSize(self) : |
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48 | """Counts pages in a DVI document. |
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49 | |
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50 | Algorithm by Jerome Alet. |
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51 | |
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52 | The documentation used for this was : |
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53 | |
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54 | http://www.math.umd.edu/~asnowden/comp-cont/dvi.html |
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55 | """ |
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56 | infileno = self.infile.fileno() |
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57 | minfile = mmap.mmap(infileno, os.fstat(infileno)[6], prot=mmap.PROT_READ, flags=mmap.MAP_SHARED) |
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58 | pagecount = 0 |
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59 | pos = -1 |
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60 | eofchar = chr(0xdf) |
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61 | postchar = chr(0xf8) |
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62 | try : |
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63 | try : |
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64 | while minfile[pos] == eofchar : |
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65 | pos -= 1 |
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66 | idbyte = minfile[pos] |
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67 | if idbyte != minfile[1] : |
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68 | raise IndexError, "Invalid DVI file." |
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69 | pos = unpack(">I", minfile[pos - 4:pos])[0] |
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70 | if minfile[pos] != postchar : |
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71 | raise IndexError, "Invalid DVI file." |
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72 | pagecount = unpack(">H", minfile[pos + 27: pos + 29])[0] |
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73 | except IndexError : # EOF ? |
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74 | pass |
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75 | finally : |
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76 | minfile.close() # reached EOF |
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77 | return pagecount |
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