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