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annotate core/image_uploader.py @ 901:147a66da9cbc

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author Brian Neal <bgneal@gmail.com>
date Sat, 07 Mar 2015 14:11:50 -0600
parents ee47122d6277
children 51a2051588f5
rev   line source
bgneal@700 1 """This module contains a function to upload an image file to a S3Bucket.
bgneal@696 2
bgneal@700 3 The image can be resized and a thumbnail can be generated and uploaded as well.
bgneal@696 4
bgneal@696 5 """
bgneal@885 6 from base64 import b64encode
bgneal@696 7 import logging
bgneal@696 8 from io import BytesIO
bgneal@696 9 import os.path
bgneal@700 10 import tempfile
bgneal@696 11 import uuid
bgneal@696 12
bgneal@696 13 from PIL import Image
bgneal@696 14
bgneal@700 15 from core.functions import temp_open
bgneal@837 16 from core.image import orient_image
bgneal@700 17
bgneal@696 18
bgneal@696 19 logger = logging.getLogger(__name__)
bgneal@696 20
bgneal@696 21
bgneal@885 22 def make_key():
bgneal@885 23 """Generate a random key suitable for a filename"""
bgneal@885 24 return b64encode(uuid.uuid4().bytes, '-_').rstrip('=')
bgneal@885 25
bgneal@885 26
bgneal@700 27 def upload(fp, bucket, metadata=None, new_size=None, thumb_size=None):
bgneal@700 28 """Upload an image file to a given S3Bucket.
bgneal@696 29
bgneal@700 30 The image can optionally be resized and a thumbnail can be generated and
bgneal@700 31 uploaded as well.
bgneal@696 32
bgneal@700 33 Parameters:
bgneal@700 34 fp - The image file to process. This is expected to be an instance of
bgneal@700 35 Django's UploadedFile class. The file must have a name attribute and
bgneal@700 36 we expect the name to have an extension. This is extension is
bgneal@700 37 used for the uploaded image and thumbnail names.
bgneal@700 38 bucket - A core.s3.S3Bucket instance to upload to.
bgneal@700 39 metadata - If not None, must be a dictionary of metadata to apply to the
bgneal@700 40 uploaded file and thumbnail.
bgneal@700 41 new_size - If not None, the image will be resized to the dimensions
bgneal@700 42 specified by new_size, which must be a (width, height) tuple.
bgneal@700 43 thumb_size - If not None, a thumbnail image will be created with the
bgneal@700 44 dimensions specified by thumb_size, which must be a (width,
bgneal@700 45 height) tuple. The thumbnail will use the same metadata, if
bgneal@700 46 present, as the image. The thumbnail filename will be the
bgneal@700 47 same basename as the image with a 't' appended. The
bgneal@700 48 extension will be the same as the original image.
bgneal@700 49
bgneal@700 50 A tuple is returned: (image_url, thumb_url) where thumb_url will be None if
bgneal@700 51 a thumbnail was not requested.
bgneal@696 52 """
bgneal@696 53
bgneal@738 54 filename = fp.name
bgneal@737 55 logger.info('Processing image file: %s', filename)
bgneal@700 56
bgneal@700 57 # Trying to use PIL (or Pillow) on a Django UploadedFile is often
bgneal@700 58 # problematic because the file is often an in-memory file if it is under
bgneal@700 59 # a certain size. This complicates matters and many of the operations we try
bgneal@700 60 # to perform on it fail if this is the case. To get around these issues,
bgneal@700 61 # we make a copy of the file on the file system and operate on the copy.
bgneal@700 62 # First generate a unique name and temporary file path.
bgneal@885 63 unique_key = make_key()
bgneal@700 64 ext = os.path.splitext(fp.name)[1]
bgneal@700 65 temp_name = os.path.join(tempfile.gettempdir(), unique_key + ext)
bgneal@696 66
bgneal@700 67 # Write the UploadedFile to a temporary file on disk
bgneal@700 68 with temp_open(temp_name, 'wb') as temp_file:
bgneal@700 69 for chunk in fp.chunks():
bgneal@700 70 temp_file.write(chunk)
bgneal@700 71 temp_file.close()
bgneal@696 72
bgneal@837 73 # Re-orient if necessary
bgneal@837 74 image = Image.open(temp_name)
bgneal@837 75 changed, image = orient_image(image)
bgneal@837 76 if changed:
bgneal@837 77 image.save(temp_name)
bgneal@837 78
bgneal@700 79 # Resize image if necessary
bgneal@700 80 if new_size:
bgneal@700 81 image = Image.open(temp_name)
bgneal@700 82 if image.size > new_size:
bgneal@700 83 logger.debug('Resizing from {} to {}'.format(image.size, new_size))
bgneal@700 84 image.thumbnail(new_size, Image.ANTIALIAS)
bgneal@700 85 image.save(temp_name)
bgneal@696 86
bgneal@700 87 # Create thumbnail if necessary
bgneal@700 88 thumb = None
bgneal@700 89 if thumb_size:
bgneal@700 90 logger.debug('Creating thumbnail {}'.format(thumb_size))
bgneal@700 91 image = Image.open(temp_name)
bgneal@700 92 image.thumbnail(thumb_size, Image.ANTIALIAS)
bgneal@700 93 thumb = BytesIO()
bgneal@700 94 image.save(thumb, format=image.format)
bgneal@696 95
bgneal@700 96 # Upload images to S3
bgneal@700 97 file_key = unique_key + ext
bgneal@700 98 logging.debug('Uploading image')
bgneal@700 99 image_url = bucket.upload_from_filename(file_key, temp_name, metadata)
bgneal@696 100
bgneal@700 101 thumb_url = None
bgneal@700 102 if thumb:
bgneal@700 103 logging.debug('Uploading thumbnail')
bgneal@700 104 thumb_key = '{}t{}'.format(unique_key, ext)
bgneal@700 105 thumb_url = bucket.upload_from_string(thumb_key,
bgneal@700 106 thumb.getvalue(),
bgneal@700 107 metadata)
bgneal@696 108
bgneal@737 109 logger.info('Completed processing image file: %s', filename)
bgneal@696 110
bgneal@700 111 return (image_url, thumb_url)