app/django/core/files/images.py
author Daniel Bentley <dbentley@google.com>
Sun, 12 Apr 2009 09:06:45 +0000
branchgae-fetch-limitation-fix
changeset 2313 c39a81bce1bd
parent 323 ff1a9aa48cfd
permissions -rw-r--r--
Use offset_linkid instead of offset to scan >1000 entities. this is a first-cut. It works in all the ways I could make earlier versions fail. It passes link_id as URL parameters. It also has a new class LinkCreator which makes the main body of getListContents even easier to write. I wasn't sure if link_id's could have non alphanumeric characters; if so, they need to be URL encoded/decoded. I also need to go and remove any mention of raw offsets now, because we don't use them. I believe I've talked about this approach with a few of you and it sounded reasonable. Feel free to roll-back/fix/amend/comment-for-me-to-fix. This is my first big-logic-change to Melange. Patch by: Dan Bentley

"""
Utility functions for handling images.

Requires PIL, as you might imagine.
"""

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'):
            self._dimensions_cache = get_image_dimensions(self)
        return self._dimensions_cache

def get_image_dimensions(file_or_path):
    """Returns the (width, height) of an image, given an open file or a path."""
    from PIL import ImageFile as PILImageFile
    p = PILImageFile.Parser()
    if hasattr(file_or_path, 'read'):
        file = file_or_path
    else:
        file = open(file_or_path, 'rb')
    while 1:
        data = file.read(1024)
        if not data:
            break
        p.feed(data)
        if p.image:
            return p.image.size
    return None