generate thumbnails in django with pil

1from django.db import models
2from my.images import make_thumbnail
3
4
5class Image(models.Model):
6    image = models.ImageField(upload_to='')
7    thumbnail = models.ImageField(upload_to='', editable=False)
8    icon = models.ImageField(upload_to='', editable=False)
9
10    def save(self, *args, **kwargs):
11        # save for image
12        super(Image, self).save(*args, **kwargs)
13
14        make_thumbnail(self.thumbnail, self.image, (200, 200), 'thumb')
15        make_thumbnail(self.icon, self.image, (100, 100), 'icon')
16
17        # save for thumbnail and icon
18        super(Image, self).save(*args, **kwargs)
19

1from django.core.files.base import ContentFile
2import os.path
3from PIL import Image
4from io import BytesIO
5
6
7def make_thumbnail(dst_image_field, src_image_field, size, name_suffix, sep='_'):
8    """
9    make thumbnail image and field from source image field
10
11    @example
12        thumbnail(self.thumbnail, self.image, (200, 200), 'thumb')
13    """
14    # create thumbnail image
15    image = Image.open(src_image_field)
16    image.thumbnail(size, Image.ANTIALIAS)
17
18    # build file name for dst
19    dst_path, dst_ext = os.path.splitext(src_image_field.name)
20    dst_ext = dst_ext.lower()
21    dst_fname = dst_path + sep + name_suffix + dst_ext
22
23    # check extension
24    if dst_ext in ['.jpg', '.jpeg']:
25        filetype = 'JPEG'
26    elif dst_ext == '.gif':
27        filetype = 'GIF'
28    elif dst_ext == '.png':
29        filetype = 'PNG'
30    else:
31        raise RuntimeError('unrecognized file type of "%s"' % dst_ext)
32
33    # Save thumbnail to in-memory file as StringIO
34    dst_bytes = BytesIO()
35    image.save(dst_bytes, filetype)
36    dst_bytes.seek(0)
37
38    # set save=False, otherwise it will run in an infinite loop
39    dst_image_field.save(dst_fname, ContentFile(dst_bytes.read()), save=False)
40    dst_bytes.close()
41