mirror of
https://github.com/Hopiu/django-imagekit.git
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95 lines
3.5 KiB
Python
95 lines
3.5 KiB
Python
from django.conf import settings
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from django.core.files.images import ImageFile
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from django.utils.functional import LazyObject
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from ..files import BaseIKFile
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from ..registry import generator_registry
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from ..signals import before_access
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from ..utils import get_logger, get_singleton, generate, get_by_qname
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class ImageCacheFile(BaseIKFile, ImageFile):
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"""
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A file that represents the result of a generator. Creating an instance of
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this class is not enough to trigger the generation of the file. In fact,
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one of the main points of this class is to allow the creation of the file
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to be deferred until the time that the cache file strategy requires it.
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"""
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def __init__(self, generator, name=None, storage=None, cachefile_backend=None):
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"""
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:param generator: The object responsible for generating a new image.
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:param name: The filename
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:param storage: A Django storage object that will be used to save the
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file.
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:param cachefile_backend: The object responsible for managing the
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state of the file.
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"""
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self.generator = generator
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name = name or getattr(generator, 'cachefile_name', None)
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if not name:
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fn = get_by_qname(settings.IMAGEKIT_CACHEFILE_NAMER, 'namer')
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name = fn(generator)
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self.name = name
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storage = storage or getattr(generator, 'cachefile_storage',
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None) or get_singleton(settings.IMAGEKIT_DEFAULT_FILE_STORAGE,
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'file storage backend')
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self.cachefile_backend = cachefile_backend or getattr(generator,
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'cachefile_backend', None)
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super(ImageCacheFile, self).__init__(storage=storage)
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def _require_file(self):
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before_access.send(sender=self, file=self)
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return super(ImageCacheFile, self)._require_file()
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def generate(self, force=False):
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if force:
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self._generate()
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else:
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self.cachefile_backend.ensure_exists(self)
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def _generate(self):
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# Generate the file
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content = generate(self.generator)
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actual_name = self.storage.save(self.name, content)
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if actual_name != self.name:
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get_logger().warning('The storage backend %s did not save the file'
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' with the requested name ("%s") and instead used'
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' "%s". This may be because a file already existed with'
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' the requested name. If so, you may have meant to call'
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' ensure_exists() instead of generate(), or there may be a'
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' race condition in the file backend %s. The saved file'
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' will not be used.' % (self.storage,
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self.name, actual_name,
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self.cachefile_backend))
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class LazyImageCacheFile(LazyObject):
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def __init__(self, generator_id, *args, **kwargs):
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super(LazyImageCacheFile, self).__init__()
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def setup():
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generator = generator_registry.get(generator_id, *args, **kwargs)
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self._wrapped = ImageCacheFile(generator)
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self.__dict__['_setup'] = setup
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def __repr__(self):
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if self._wrapped is None:
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self._setup()
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return '<%s: %s>' % (self.__class__.__name__, self or 'None')
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def __str__(self):
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if self._wrapped is None:
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self._setup()
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return str(self._wrapped)
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def __unicode__(self):
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if self._wrapped is None:
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self._setup()
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return unicode(self._wrapped)
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