Picture support

[librarian.git] / librarian / picture.py

diff --git a/librarian/picture.py b/librarian/picture.py
new file mode 100644 (file)
index 0000000..7830528
--- /dev/null
+++ b/librarian/picture.py
@@ -0,0 +1,151 @@
+
+from dcparser import (as_person, as_date, Field, WorkInfo, DCNS)
+from librarian import (RDFNS, ValidationError, NoDublinCore, ParseError, WLURI)
+from xml.parsers.expat import ExpatError
+from os import path
+from StringIO import StringIO
+from lxml import etree
+from lxml.etree import (XMLSyntaxError, XSLTApplyError)
+import re
+
+
+class WLPictureURI(WLURI):
+    _re_wl_uri = re.compile('http://wolnelektury.pl/katalog/obraz/'
+            '(?P<slug>[-a-z0-9]+)(/(?P<lang>[a-z]{3}))?/?$')
+
+    def __init__(self, *args, **kw):
+        super(WLPictureURI, self).__init__(*args, **kw)
+
+    @classmethod
+    def from_slug_and_lang(cls, slug, lang):
+        uri = 'http://wolnelektury.pl/katalog/obraz/%s/' % slug
+        return cls(uri)
+
+    def filename_stem(self):
+        return self.slug
+
+
+class PictureInfo(WorkInfo):
+    """
+    Dublin core metadata for a picture
+    """
+    FIELDS = (
+        Field(DCNS('format.dimensions.digital'), 'dimensions', required=False),
+        Field(DCNS('format.dimensions.original'), 'dimensions_original', required=False),
+        Field(DCNS('format.physical'), 'physical', required=False),
+        Field(DCNS('format'), 'mime_type', required=False),
+        Field(DCNS('identifier.url'), 'url', WLPictureURI),
+        )
+
+    def validate(self):
+        """
+        WorkInfo has a language validation code only, which we do not need.
+        """
+        pass
+    
+
+class ImageStore(object):
+    EXT = ['gif', 'jpeg', 'png', 'swf', 'psd', 'bmp'
+            'tiff', 'tiff', 'jpc', 'jp2', 'jpf', 'jb2', 'swc',
+            'aiff', 'wbmp', 'xbm']
+    MIME = ['image/gif', 'image/jpeg', 'image/png',
+            'application/x-shockwave-flash', 'image/psd', 'image/bmp',
+            'image/tiff', 'image/tiff', 'application/octet-stream',
+            'image/jp2', 'application/octet-stream', 'application/octet-stream',
+            'application/x-shockwave-flash', 'image/iff', 'image/vnd.wap.wbmp', 'image/xbm']
+
+    def __init__(self, dir_):
+        self.dir = dir_
+        return super(ImageStore, self).__init__()
+
+    def path(self, slug, mime_type):
+        """
+        Finds file by slug and mime type in our iamge store.
+        Returns a file objects (perhaps should return a filename?)
+        """
+        try:
+            i = self.MIME.index(mime_type)
+        except ValueError:
+            err = ValueError("Picture %s has unknown mime type: %s" % (slug, mime_type))
+            err.slug = slug
+            err.mime_type = mime_type
+            raise err
+        ext = self.EXT[i]
+        # add some common extensions tiff->tif, jpeg->jpg
+        return path.join(self.dir, slug + '.' + ext)
+
+
+class WLPicture(object):
+    def __init__(self, edoc, parse_dublincore=True, image_store=None):
+        self.edoc = edoc
+        self.image_store = image_store
+
+        root_elem = edoc.getroot()
+
+        dc_path = './/' + RDFNS('RDF')
+
+        if root_elem.tag != 'picture':
+            raise ValidationError("Invalid root element. Found '%s', should be 'picture'" % root_elem.tag)
+
+        if parse_dublincore:
+            self.rdf_elem = root_elem.find(dc_path)
+
+            if self.rdf_elem is None:
+                raise NoDublinCore('Document has no DublinCore - which is required.')
+
+            self.picture_info = PictureInfo.from_element(self.rdf_elem)
+        else:
+            self.picture_info = None
+
+    @classmethod
+    def from_string(cls, xml, *args, **kwargs):
+        return cls.from_file(StringIO(xml), *args, **kwargs)
+
+    @classmethod
+    def from_file(cls, xmlfile, parse_dublincore=True, image_store=None):
+
+        # first, prepare for parsing
+        if isinstance(xmlfile, basestring):
+            file = open(xmlfile, 'rb')
+            try:
+                data = file.read()
+            finally:
+                file.close()
+        else:
+            data = xmlfile.read()
+
+        if not isinstance(data, unicode):
+            data = data.decode('utf-8')
+
+        data = data.replace(u'\ufeff', '')
+
+        # assume images are in the same directory
+        if image_store is None and xmlfile.name is not None:
+            image_store = ImageStore(path.dirname(xmlfile.name))
+
+        try:
+            parser = etree.XMLParser(remove_blank_text=False)
+            tree = etree.parse(StringIO(data.encode('utf-8')), parser)
+
+            return cls(tree, parse_dublincore=parse_dublincore, image_store=image_store)
+        except (ExpatError, XMLSyntaxError, XSLTApplyError), e:
+            raise ParseError(e)
+
+    @property
+    def mime_type(self):
+        if self.picture_info is None:
+            raise ValueError('DC is not loaded, hence we don\'t know the image type')
+        return self.picture_info.mime_type
+
+    @property
+    def slug(self):
+        return self.picture_info.url.slug
+
+    @property
+    def image_path(self):
+        if self.image_store is None:
+            raise ValueError("No image store associated with whis WLPicture.")
+        return self.image_store.path(self.slug, self.mime_type)
+
+    def image_file(self, *args, **kwargs):
+        return open(self.image_path, *args, **kwargs)