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"""
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'):
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.
"""
# Try to import PIL in either of the two ways it can end up installed.
try:
from PIL import ImageFile as PILImageFile
except ImportError:
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
p.feed(data)
if p.image:
return p.image.size
chunk_size = chunk_size*2
return None
finally:
if close:
file.close()
else:
file.seek(file_pos)
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