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- """
- Utility functions for handling images.
- Requires Pillow (or PIL), as you might imagine.
- """
- import zlib
- from django.core.files import File
- class ImageFile(File):
- """
- A mixin for use alongside django.core.files.base.File, which provides
- additional features for dealing with images.
- """
- def _get_width(self):
- return self._get_image_dimensions()[0]
- width = property(_get_width)
- def _get_height(self):
- return self._get_image_dimensions()[1]
- height = property(_get_height)
- def _get_image_dimensions(self):
- if not hasattr(self, '_dimensions_cache'):
- close = self.closed
- self.open()
- self._dimensions_cache = get_image_dimensions(self, close=close)
- return self._dimensions_cache
- def get_image_dimensions(file_or_path, close=False):
- """
- Returns the (width, height) of an image, given an open file or a path. Set
- 'close' to True to close the file at the end if it is initially in an open
- state.
- """
- from django.utils.image import ImageFile as PILImageFile
- p = PILImageFile.Parser()
- if hasattr(file_or_path, 'read'):
- file = file_or_path
- file_pos = file.tell()
- file.seek(0)
- else:
- file = open(file_or_path, 'rb')
- close = True
- try:
- # Most of the time PIL only needs a small chunk to parse the image and
- # get the dimensions, but with some TIFF files PIL needs to parse the
- # whole file.
- chunk_size = 1024
- while 1:
- data = file.read(chunk_size)
- if not data:
- break
- try:
- p.feed(data)
- except zlib.error as e:
- # ignore zlib complaining on truncated stream, just feed more
- # data to parser (ticket #19457).
- if e.args[0].startswith("Error -5"):
- pass
- else:
- raise
- if p.image:
- return p.image.size
- chunk_size *= 2
- return None
- finally:
- if close:
- file.close()
- else:
- file.seek(file_pos)
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