git.polytechnique.org Git - xnet/blob - xnet/utils/images/fields.py

   1 # -*- encoding: utf-8 -*-
   2 """
   3 django-thumbs by Antonio Melé
   4 Modified by Arthur Darcet to support on demand resizing
   5 """
   6 from django.db.models import ImageField
   7 from django.db.models.fields.files import ImageFieldFile
   8 from PIL import Image
   9 from django.core.files.base import ContentFile
  10 import cStringIO, re
  11
  12
  13 def generate_thumb(img, thumb_size, format):
  14     img.seek(0) # see http://code.djangoproject.com/ticket/8222 for details
  15     image = Image.open(img)
  16     if image.mode not in ('L', 'RGB'):
  17         image = image.convert('RGB')
  18     thumb_w, thumb_h = thumb_size
  19     if thumb_w == thumb_h and False:
  20         xsize, ysize = image.size
  21         minsize = min(xsize,ysize)
  22         xnewsize = (xsize-minsize)/2
  23         ynewsize = (ysize-minsize)/2
  24         image2 = image.crop((xnewsize, ynewsize, xsize-xnewsize, ysize-ynewsize))
  25         image2.load()
  26         image2.thumbnail(thumb_size, Image.ANTIALIAS)
  27     else:
  28         image2 = image
  29         image2.thumbnail(thumb_size, Image.ANTIALIAS)
  30     io = cStringIO.StringIO()
  31     if format.upper()=='JPG':
  32         format = 'JPEG'
  33     image2.save(io, format)
  34     return ContentFile(io.getvalue())
  35
  36
  37 class ImageWithThumbsFieldFile(ImageFieldFile):
  38     @staticmethod
  39     def _get_for_size(s, (w,h)):
  40         split = s.rsplit('.',1)
  41         return u'{}.{}x{}.{}'.format(split[0],w,h,split[1])
  42
  43     def __getattr__(self, attr):
  44         s = attr.split('url_')
  45         if len(s) != 2 or 'x' not in s[1]:
  46             raise AttributeError
  47         if not self.name:
  48             raise AttributeError('The picture has no file associated with it.')
  49         size = map(int, s[1].split('x',1))
  50         name = ImageWithThumbsFieldFile._get_for_size(self.name, size)
  51         url = ImageWithThumbsFieldFile._get_for_size(self.url, size)
  52         if not self.storage.exists(name):
  53             thumb_content = generate_thumb(self, size, name.rsplit('.',1)[1])
  54             self.storage.save(name, thumb_content)
  55         return url
  56
  57     def delete(self, save=True):
  58         directory, name = self.name.rsplit('/', 1)
  59         _, files = self.storage.listdir(directory)
  60         reg = re.compile(r'{}.[0-9]+x[0-9]+.{}'.format(*name.rsplit('.',1)))
  61         for f in files:
  62             if reg.match(f):
  63                 self.storage.delete(u'{}/{}'.format(directory, f))
  64         super(ImageWithThumbsFieldFile, self).delete(save)
  65
  66
  67 class ImageWithThumbsField(ImageField):
  68     attr_class = ImageWithThumbsFieldFile
  69     """
  70     Usage example:
  71     ==============
  72     photo = ImageWithThumbsField(upload_to='images', sizes=((125,125),(300,200),)
  73
  74     To retrieve image URL, exactly the same way as with ImageField:
  75         my_object.photo.url
  76     To retrieve thumbnails URL's just add the size to it:
  77         my_object.photo.url_125x125
  78         my_object.photo.url_300x200
  79
  80     Note: The 'sizes' attribute is not required. If you don't provide it,
  81     ImageWithThumbsField will act as a normal ImageField
  82
  83     How it works:
  84     =============
  85     For each size in the 'sizes' atribute of the field it generates a
  86     thumbnail with that size and stores it following this format:
  87
  88     available_filename.[width]x[height].extension
  89
  90     Where 'available_filename' is the available filename returned by the storage
  91     backend for saving the original file.
  92
  93     Following the usage example above: For storing a file called "photo.jpg" it saves:
  94     photo.jpg          (original file)
  95     photo.125x125.jpg  (first thumbnail)
  96     photo.300x200.jpg  (second thumbnail)
  97
  98     With the default storage backend if photo.jpg already exists it will use these filenames:
  99     photo_.jpg
 100     photo_.125x125.jpg
 101     photo_.300x200.jpg
 102
 103     Note: django-thumbs assumes that if filename "any_filename.jpg" is available
 104     filenames with this format "any_filename.[widht]x[height].jpg" will be available, too.
 105
 106     To do:
 107     ======
 108     Add method to regenerate thubmnails
 109
 110     """
 111     def __init__(self, verbose_name=None, name=None, width_field=None, height_field=None, **kwargs):
 112         self.verbose_name=verbose_name
 113         self.name=name
 114         self.width_field=width_field
 115         self.height_field=height_field
 116         super(ImageField, self).__init__(**kwargs)