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from uuid import uuid4 from zope.interface import Interface from zope.interface import implements from zope.annotation import IAnnotations from UserDict import DictMixin class IImageScaleStorage(Interface): """ adapter for image content and field which can store, retrieve and generate image scale data """ def scale(create=True, **parameters): """ find or optionally create image scale data using the given parameters, which can be anything supported by `scaleImage` """ def __getitem__(uid): """ find image scale data based on its uid """ class AbstractStorage(DictMixin): """ an abstract storage for image scales using annotations """ implements(IImageScaleStorage) def __init__(self, context, field): self.context = context self.field = field @property def fieldname(self): return self.field.getName() @property def storage(self): return IAnnotations(self.context).setdefault('scales', {}) def create(self, **parameters): raise NotImplemented def hash(self, **parameters): return tuple(sorted(parameters.items())) def scale(self, create=True, **parameters): key = self.hash(fieldname=self.fieldname, **parameters) storage = self.storage info = storage.get(key) if info is None and create: data, format, dimensions = self.create(**parameters) width, height = dimensions uid = str(uuid4()) info = dict(id=uid, data=data, width=width, height=height, mimetype='image/%s' % format.lower(), key=key) storage[key] = storage[uid] = info return info def __getitem__(self, uid): return self.storage[uid] def __delitem__(self, uid): storage = self.storage info = storage[uid] del storage[info['key']] del storage[uid] def __iter__(self): return iter(self.storage) def keys(self): return self.storage.keys() def has_key(self, uid): return self.storage.has_key(uid) __contains__ = has_key

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