xmp.py

   1 # -*- coding: utf-8 -*-
   2 #######################################################################################
   3 #   Photo is a part of Plinn - http://plinn.org                                       #
   4 #   Copyright © 2008  Benoît PIN <benoit.pin@ensmp.fr>                                #
   5 #                                                                                     #
   6 #   This program is free software; you can redistribute it and/or                     #
   7 #   modify it under the terms of the GNU General Public License                       #
   8 #   as published by the Free Software Foundation; either version 2                    #
   9 #   of the License, or (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, write to the Free Software                       #
  18 #   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.   #
  19 #######################################################################################
  20 # $Id: xmp.py 354 2008-02-13 13:30:53Z pin $
  21 # $URL: http://svn.luxia.fr/svn/labo/projects/zope/Photo/trunk/xmp.py $
  22
  23 from types import StringTypes
  24 from logging import getLogger
  25 import re
  26 console = getLogger('Photo.xmp')
  27
  28 class XMP(object) :
  29         XMP_HEADER = u'<?xpacket begin="\ufeff" id="W5M0MpCehiHzreSzNTczkc9d"?>'
  30         XMP_HEADER_PATTERN = u'''<\?xpacket begin=['"]\ufeff['"] id=['"]W5M0MpCehiHzreSzNTczkc9d['"][^\?]*\?>'''
  31         XMP_PADDING_LINE = u'\u0020' * 63 + u'\n'
  32         XMP_TRAILER = u'<?xpacket end="w"?>'
  33
  34         _readers = {}
  35         _writers = {}
  36
  37
  38
  39         def __init__(self, file, content_type='image/jpeg', encoding='utf-8') :
  40                 try :
  41                         self.reader = self._readers[content_type]
  42                 except KeyError:
  43                         raise NotImplementedError, "%r content type not supported by XMP" % content_type
  44
  45                 try :
  46                         self.writer = self._writers[content_type]
  47                 except KeyError :
  48                         self.writer = None
  49                         console.info('XMP file opened on read-only mode.')
  50
  51                 self.file = file
  52                 self.encoding = encoding
  53                 self.xmp = None
  54                 self._open()
  55
  56
  57         def __del__(self) :
  58                 try :
  59                         self.file.close()
  60                 except :
  61                         pass
  62
  63
  64         def _open(self) :
  65
  66                 if type(self.file) in StringTypes :
  67                         self.file = file(self.file)
  68
  69                 packet = self.reader(self.file)
  70
  71                 if packet is not None :
  72                         # tests / unwrap
  73                         reEncodedHeader = re.compile(self.XMP_HEADER_PATTERN.encode(self.encoding))
  74                         m = reEncodedHeader.match(packet)
  75                         assert m is not None, "No xmp header found"
  76                         xmp = packet[m.end():]
  77
  78                         trailer = self.XMP_TRAILER[:-6].encode(self.encoding)  # TODO handle read-only mode
  79                         trailerPos = xmp.find(trailer)
  80                         assert trailerPos != -1, "No xmp trailer found"
  81
  82                         xmp = xmp[:trailerPos]
  83                         xmp = xmp.strip()
  84                         self.xmp = xmp
  85                 else :
  86                         self.xmp = None
  87
  88         def save(self, f=None):
  89                 original = self.file
  90                 if f :
  91                         if type(f) in StringTypes :
  92                                 new = file(f, 'w')
  93                         else :
  94                                 new = f
  95                 elif f is None :
  96                         new = self.file
  97
  98                 self.writer(original, new, self.xmp)
  99
 100
 101         def getXMP(self) :
 102                 return self.xmp
 103
 104
 105         def setXMP(self, xmp) :
 106                 self.xmp = xmp
 107
 108         #
 109         # xmp utils
 110         #
 111
 112         @staticmethod
 113         def getXmpPadding(size) :
 114                 # size of trailer in kB
 115                 return (XMP.XMP_PADDING_LINE * 32 * size)
 116
 117
 118         @staticmethod
 119         def genXMPPacket(uXmpData, paddingSize):
 120                 packet = u''
 121
 122                 packet += XMP.XMP_HEADER
 123                 packet += uXmpData
 124                 packet += XMP.getXmpPadding(paddingSize)
 125                 packet += XMP.XMP_TRAILER
 126
 127                 return packet
 128
 129
 130
 131         #
 132         # content type registry stuff
 133         #
 134
 135
 136         @classmethod
 137         def registerReader(cls, content_type, reader) :
 138                 cls._readers[content_type] = reader
 139
 140         @classmethod
 141         def registerWriter(cls, content_type, writer) :
 142                 cls._writers[content_type] = writer
 143
 144         @classmethod
 145         def registerWrapper(cls, content_type, wrapper) :
 146                 """ Registers specific wrapper to prepare data
 147                         for embedding xmp into specific content_type file.
 148                 """
 149                 pass
 150
 151
 152
 153 def test() :
 154         from xml.dom.minidom import parse
 155         data = parse('new.xmp').documentElement.toxml()
 156
 157         def test1() :
 158                 original = 'original.jpg'
 159                 modified = 'modified.jpg'
 160
 161                 x = XMP(original)
 162                 x.setXMP(data)
 163                 x.save(modified)
 164
 165         def test2() :
 166                 from cStringIO import StringIO
 167                 sio = StringIO()
 168                 sio.write(file('modified.jpg').read())
 169                 sio.seek(0)
 170
 171                 x = XMP(sio)
 172                 x.setXMP(data)
 173                 x.save()
 174
 175                 f2 = open('modified2.jpg', 'w')
 176                 f2.write(sio.read())
 177                 f2.close()
 178
 179
 180         test1()
 181         test2()
 182
 183
 184
 185 if __name__ == '__main__' :
 186         test()