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