librarian/picture.py

   1
   2 from dcparser import (as_person, as_date, Field, WorkInfo, DCNS)
   3 from librarian import (RDFNS, ValidationError, NoDublinCore, ParseError, WLURI)
   4 from xml.parsers.expat import ExpatError
   5 from os import path
   6 from StringIO import StringIO
   7 from lxml import etree
   8 from lxml.etree import (XMLSyntaxError, XSLTApplyError)
   9 import re
  10
  11
  12 class WLPictureURI(WLURI):
  13     _re_wl_uri = re.compile('http://wolnelektury.pl/katalog/obraz/'
  14             '(?P<slug>[-a-z0-9]+)/?$')
  15
  16     @classmethod
  17     def from_slug(cls, slug):
  18         uri = 'http://wolnelektury.pl/katalog/obraz/%s/' % slug
  19         return cls(uri)
  20
  21 def as_wlpictureuri_strict(text):
  22     return WLPictureURI.strict(text)
  23
  24
  25 class PictureInfo(WorkInfo):
  26     """
  27     Dublin core metadata for a picture
  28     """
  29     FIELDS = (
  30         Field(DCNS('language'), 'language', required=False),
  31         Field(DCNS('subject.period'), 'epochs', salias='epoch', multiple=True),
  32         Field(DCNS('subject.type'), 'kinds', salias='kind', multiple=True),
  33
  34         Field(DCNS('format.dimensions'), 'dimensions', required=False),
  35         Field(DCNS('format.checksum.sha1'), 'sha1', required=True),
  36         Field(DCNS('description.medium'), 'medium', required=False),
  37         Field(DCNS('description.dimensions'), 'original_dimensions', required=False),
  38         Field(DCNS('format'), 'mime_type', required=False),
  39         Field(DCNS('identifier.url'), 'url', WLPictureURI,
  40             strict=as_wlpictureuri_strict),
  41         )
  42
  43
  44 class ImageStore(object):
  45     EXT = ['gif', 'jpeg', 'png', 'swf', 'psd', 'bmp'
  46             'tiff', 'tiff', 'jpc', 'jp2', 'jpf', 'jb2', 'swc',
  47             'aiff', 'wbmp', 'xbm']
  48     MIME = ['image/gif', 'image/jpeg', 'image/png',
  49             'application/x-shockwave-flash', 'image/psd', 'image/bmp',
  50             'image/tiff', 'image/tiff', 'application/octet-stream',
  51             'image/jp2', 'application/octet-stream', 'application/octet-stream',
  52             'application/x-shockwave-flash', 'image/iff', 'image/vnd.wap.wbmp', 'image/xbm']
  53
  54     def __init__(self, dir_):
  55         self.dir = dir_
  56         return super(ImageStore, self).__init__()
  57
  58     def path(self, slug, mime_type):
  59         """
  60         Finds file by slug and mime type in our iamge store.
  61         Returns a file objects (perhaps should return a filename?)
  62         """
  63         try:
  64             i = self.MIME.index(mime_type)
  65         except ValueError:
  66             err = ValueError("Picture %s has unknown mime type: %s" % (slug, mime_type))
  67             err.slug = slug
  68             err.mime_type = mime_type
  69             raise err
  70         ext = self.EXT[i]
  71         # add some common extensions tiff->tif, jpeg->jpg
  72         return path.join(self.dir, slug + '.' + ext)
  73
  74
  75 class WLPicture(object):
  76     def __init__(self, edoc, parse_dublincore=True, image_store=None):
  77         self.edoc = edoc
  78         self.image_store = image_store
  79
  80         root_elem = edoc.getroot()
  81
  82         dc_path = './/' + RDFNS('RDF')
  83
  84         if root_elem.tag != 'picture':
  85             raise ValidationError("Invalid root element. Found '%s', should be 'picture'" % root_elem.tag)
  86
  87         if parse_dublincore:
  88             self.rdf_elem = root_elem.find(dc_path)
  89
  90             if self.rdf_elem is None:
  91                 raise NoDublinCore('Document has no DublinCore - which is required.')
  92
  93             self.picture_info = PictureInfo.from_element(self.rdf_elem)
  94         else:
  95             self.picture_info = None
  96
  97     @classmethod
  98     def from_string(cls, xml, *args, **kwargs):
  99         return cls.from_file(StringIO(xml), *args, **kwargs)
 100
 101     @classmethod
 102     def from_file(cls, xmlfile, parse_dublincore=True, image_store=None):
 103
 104         # first, prepare for parsing
 105         if isinstance(xmlfile, basestring):
 106             file = open(xmlfile, 'rb')
 107             try:
 108                 data = file.read()
 109             finally:
 110                 file.close()
 111         else:
 112             data = xmlfile.read()
 113
 114         if not isinstance(data, unicode):
 115             data = data.decode('utf-8')
 116
 117         data = data.replace(u'\ufeff', '')
 118
 119         # assume images are in the same directory
 120         if image_store is None and xmlfile.name is not None:
 121             image_store = ImageStore(path.dirname(xmlfile.name))
 122
 123         try:
 124             parser = etree.XMLParser(remove_blank_text=False)
 125             tree = etree.parse(StringIO(data.encode('utf-8')), parser)
 126
 127             return cls(tree, parse_dublincore=parse_dublincore, image_store=image_store)
 128         except (ExpatError, XMLSyntaxError, XSLTApplyError), e:
 129             raise ParseError(e)
 130
 131     @property
 132     def mime_type(self):
 133         if self.picture_info is None:
 134             raise ValueError('DC is not loaded, hence we don\'t know the image type')
 135         return self.picture_info.mime_type
 136
 137     @property
 138     def slug(self):
 139         return self.picture_info.url.slug
 140
 141     @property
 142     def image_path(self):
 143         if self.image_store is None:
 144             raise ValueError("No image store associated with whis WLPicture.")
 145         return self.image_store.path(self.slug, self.mime_type)
 146
 147     def image_file(self, *args, **kwargs):
 148         return open(self.image_path, *args, **kwargs)
 149
 150     def partiter(self):
 151         """
 152         Iterates the parts of this picture and returns them and their metadata
 153         """
 154         for part in self.edoc.iter("div"):
 155             pd = {}
 156             pd['type'] = part.get('type')
 157             if pd['type'] == 'area':
 158                 pd['coords'] = ((int(part.get('x1')), int(part.get('y1'))),
 159                                 (int(part.get('x2')), int(part.get('y2'))))
 160
 161             pd['themes'] = []
 162             pd['object'] = None
 163             parent = part
 164             while True:
 165                 parent = parent.getparent()
 166                 if parent is None:
 167                     break
 168                 if parent.tag == 'sem':
 169                     if parent.get('type') == 'theme':
 170                         pd['themes'] += map(unicode.strip, unicode(parent.get('theme')).split(','))
 171                     elif parent.get('type') == 'object' and pd['object'] is None:
 172                         pd['object'] = parent.get('object')
 173             yield pd