--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/core/image_uploader.py	Wed Sep 11 20:31:23 2013 -0500
@@ -0,0 +1,97 @@
+"""This module contains a function to upload an image file to a S3Bucket.
+
+The image can be resized and a thumbnail can be generated and uploaded as well.
+
+"""
+import logging
+from io import BytesIO
+import os.path
+import tempfile
+import uuid
+
+from PIL import Image
+
+from core.functions import temp_open
+
+
+logger = logging.getLogger(__name__)
+
+
+def upload(fp, bucket, metadata=None, new_size=None, thumb_size=None):
+    """Upload an image file to a given S3Bucket.
+
+    The image can optionally be resized and a thumbnail can be generated and
+    uploaded as well.
+
+    Parameters:
+        fp - The image file to process. This is expected to be an instance of
+             Django's UploadedFile class. The file must have a name attribute and
+             we expect the name to have an extension. This is extension is
+             used for the uploaded image and thumbnail names.
+        bucket - A core.s3.S3Bucket instance to upload to.
+        metadata - If not None, must be a dictionary of metadata to apply to the
+                   uploaded file and thumbnail.
+        new_size - If not None, the image will be resized to the dimensions
+                   specified by new_size, which must be a (width, height) tuple.
+        thumb_size - If not None, a thumbnail image will be created with the
+                     dimensions specified by thumb_size, which must be a (width,
+                     height) tuple. The thumbnail will use the same metadata, if
+                     present, as the image. The thumbnail filename will be the
+                     same basename as the image with a 't' appended. The
+                     extension will be the same as the original image.
+
+    A tuple is returned: (image_url, thumb_url) where thumb_url will be None if
+    a thumbnail was not requested.
+    """
+
+    logger.info('Processing image file: {}'.format(fp.name))
+
+    # Trying to use PIL (or Pillow) on a Django UploadedFile is often
+    # problematic because the file is often an in-memory file if it is under
+    # a certain size. This complicates matters and many of the operations we try
+    # to perform on it fail if this is the case. To get around these issues,
+    # we make a copy of the file on the file system and operate on the copy.
+    # First generate a unique name and temporary file path.
+    unique_key = uuid.uuid4().hex
+    ext = os.path.splitext(fp.name)[1]
+    temp_name = os.path.join(tempfile.gettempdir(), unique_key + ext)
+
+    # Write the UploadedFile to a temporary file on disk
+    with temp_open(temp_name, 'wb') as temp_file:
+        for chunk in fp.chunks():
+            temp_file.write(chunk)
+        temp_file.close()
+
+        # Resize image if necessary
+        if new_size:
+            image = Image.open(temp_name)
+            if image.size > new_size:
+                logger.debug('Resizing from {} to {}'.format(image.size, new_size))
+                image.thumbnail(new_size, Image.ANTIALIAS)
+                image.save(temp_name)
+
+        # Create thumbnail if necessary
+        thumb = None
+        if thumb_size:
+            logger.debug('Creating thumbnail {}'.format(thumb_size))
+            image = Image.open(temp_name)
+            image.thumbnail(thumb_size, Image.ANTIALIAS)
+            thumb = BytesIO()
+            image.save(thumb, format=image.format)
+
+        # Upload images to S3
+        file_key = unique_key + ext
+        logging.debug('Uploading image')
+        image_url = bucket.upload_from_filename(file_key, temp_name, metadata)
+
+    thumb_url = None
+    if thumb:
+        logging.debug('Uploading thumbnail')
+        thumb_key = '{}t{}'.format(unique_key, ext)
+        thumb_url = bucket.upload_from_string(thumb_key,
+                                              thumb.getvalue(),
+                                              metadata)
+
+    logger.info('Completed processing image file: {}'.format(fp.name))
+
+    return (image_url, thumb_url)