81 lines
2.3 KiB
Python
81 lines
2.3 KiB
Python
"""
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Utility functions for handling images.
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Requires Pillow as you might imagine.
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"""
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import struct
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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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@property
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def width(self):
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return self._get_image_dimensions()[0]
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@property
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def height(self):
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return self._get_image_dimensions()[1]
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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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Return 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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from PIL import ImageFile as PillowImageFile
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p = PillowImageFile.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 Pillow only needs a small chunk to parse the image
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# and get the dimensions, but with some TIFF files Pillow needs to
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# parse the 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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except struct.error:
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# Ignore PIL failing on a too short buffer when reads return
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# less bytes than expected. Skip and feed more data to the
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# parser (ticket #24544).
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pass
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if p.image:
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return p.image.size
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chunk_size *= 2
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return (None, 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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