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 #
  21 #
  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                         if m is None :
  76                                 console.warn('XMP packet wrapper not found')
  77                                 self.xmp = packet
  78                                 return
  79
  80                         xmp = packet[m.end():]
  81                         trailer = self.XMP_TRAILER[:-6].encode(self.encoding)  # TODO handle read-only mode
  82                         trailerPos = xmp.find(trailer)
  83                         assert trailerPos != -1, "No xmp trailer found"
  84
  85                         xmp = xmp[:trailerPos]
  86                         xmp = xmp.strip()
  87                         self.xmp = xmp
  88                 else :
  89                         self.xmp = None
  90
  91         def save(self, f=None):
  92                 original = self.file
  93                 if f :
  94                         if type(f) in StringTypes :
  95                                 new = file(f, 'w')
  96                         else :
  97                                 new = f
  98                 elif f is None :
  99                         new = self.file
 100
 101                 self.writer(original, new, self.xmp)
 102
 103
 104         def getXMP(self) :
 105                 return self.xmp
 106
 107
 108         def setXMP(self, xmp) :
 109                 self.xmp = xmp
 110
 111         #
 112         # xmp utils
 113         #
 114
 115         @staticmethod
 116         def getXmpPadding(size) :
 117                 # size of trailer in kB
 118                 return (XMP.XMP_PADDING_LINE * 32 * size)
 119
 120
 121         @staticmethod
 122         def genXMPPacket(uXmpData, paddingSize):
 123                 packet = u''
 124
 125                 packet += XMP.XMP_HEADER
 126                 packet += uXmpData
 127                 packet += XMP.getXmpPadding(paddingSize)
 128                 packet += XMP.XMP_TRAILER
 129
 130                 return packet
 131
 132
 133
 134         #
 135         # content type registry stuff
 136         #
 137
 138
 139         @classmethod
 140         def registerReader(cls, content_type, reader) :
 141                 cls._readers[content_type] = reader
 142
 143         @classmethod
 144         def registerWriter(cls, content_type, writer) :
 145                 cls._writers[content_type] = writer
 146
 147         @classmethod
 148         def registerWrapper(cls, content_type, wrapper) :
 149                 """ Registers specific wrapper to prepare data
 150                         for embedding xmp into specific content_type file.
 151                 """
 152                 pass
 153
 154
 155
 156 def test() :
 157         from xml.dom.minidom import parse
 158         data = parse('new.xmp').documentElement.toxml()
 159
 160         def test1() :
 161                 original = 'original.jpg'
 162                 modified = 'modified.jpg'
 163
 164                 x = XMP(original)
 165                 x.setXMP(data)
 166                 x.save(modified)
 167
 168         def test2() :
 169                 from cStringIO import StringIO
 170                 sio = StringIO()
 171                 sio.write(file('modified.jpg').read())
 172                 sio.seek(0)
 173
 174                 x = XMP(sio)
 175                 x.setXMP(data)
 176                 x.save()
 177
 178                 f2 = open('modified2.jpg', 'w')
 179                 f2.write(sio.read())
 180                 f2.close()
 181
 182
 183         test1()
 184         test2()
 185
 186
 187
 188 if __name__ == '__main__' :
 189         test()