# Django 2.2.9.dev20191202104323 文档

# django.core.files.images 源代码

    """
    Utility functions for handling images.

    Requires Pillow as you might imagine.
    """
    import struct
    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.
        """
        @property
        def width(self):
            return self._get_image_dimensions()[0]

        @property
        def height(self):
            return self._get_image_dimensions()[1]

        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):
        """
        Return 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 PIL import ImageFile as PillowImageFile

        p = PillowImageFile.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 Pillow only needs a small chunk to parse the image
            # and get the dimensions, but with some TIFF files Pillow 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
                except struct.error:
                    # Ignore PIL failing on a too short buffer when reads return
                    # less bytes than expected. Skip and feed more data to the
                    # parser (ticket #24544).
                    pass
                except RuntimeError:
                    # e.g. "RuntimeError: could not create decoder object" for
                    # WebP files. A different chunk_size may work.
                    pass
                if p.image:
                    return p.image.size
                chunk_size *= 2
            return (None, None)
        finally:
            if close:
                file.close()
            else:
                file.seek(file_pos)