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thumbs.py
214 lines | 7.3 KiB | text/x-python | PythonLexer
# -*- encoding: utf-8 -*-
"""
django-thumbs by Antonio Melé
http://django.es
"""
from django.core.files.images import ImageFile
from django.db.models import ImageField
from django.db.models.fields.files import ImageFieldFile
from PIL import Image
from django.core.files.base import ContentFile
import io
def generate_thumb(img, thumb_size, format):
"""
Generates a thumbnail image and returns a ContentFile object with the thumbnail
Parameters:
===========
img File object
thumb_size desired thumbnail size, ie: (200,120)
format format of the original image ('jpeg','gif','png',...)
(this format will be used for the generated thumbnail, too)
"""
img.seek(0) # see http://code.djangoproject.com/ticket/8222 for details
image = Image.open(img)
# get size
thumb_w, thumb_h = thumb_size
# If you want to generate a square thumbnail
if thumb_w == thumb_h:
# quad
xsize, ysize = image.size
# get minimum size
minsize = min(xsize, ysize)
# largest square possible in the image
xnewsize = (xsize - minsize) / 2
ynewsize = (ysize - minsize) / 2
# crop it
image2 = image.crop(
(xnewsize, ynewsize, xsize - xnewsize, ysize - ynewsize))
# load is necessary after crop
image2.load()
# thumbnail of the cropped image (with ANTIALIAS to make it look better)
image2.thumbnail(thumb_size, Image.ANTIALIAS)
else:
# not quad
image2 = image
image2.thumbnail(thumb_size, Image.ANTIALIAS)
output = io.BytesIO()
# PNG and GIF are the same, JPG is JPEG
if format.upper() == 'JPG':
format = 'JPEG'
image2.save(output, format)
return ContentFile(output.getvalue())
class ImageWithThumbsFieldFile(ImageFieldFile):
"""
See ImageWithThumbsField for usage example
"""
def __init__(self, *args, **kwargs):
super(ImageWithThumbsFieldFile, self).__init__(*args, **kwargs)
self.sizes = self.field.sizes
if self.sizes:
def get_size(self, size):
if not self:
return ''
else:
split = self.url.rsplit('.', 1)
thumb_url = '%s.%sx%s.%s' % (split[0], w, h, split[1])
return thumb_url
for size in self.sizes:
(w, h) = size
setattr(self, 'url_%sx%s' % (w, h), get_size(self, size))
def save(self, name, content, save=True):
super(ImageWithThumbsFieldFile, self).save(name, content, save)
if self.sizes:
for size in self.sizes:
(w, h) = size
split = self.name.rsplit('.', 1)
thumb_name = '%s.%sx%s.%s' % (split[0], w, h, split[1])
# you can use another thumbnailing function if you like
thumb_content = generate_thumb(content, size, split[1])
thumb_name_ = self.storage.save(thumb_name, thumb_content)
if not thumb_name == thumb_name_:
raise ValueError(
'There is already a file named %s' % thumb_name)
def delete(self, save=True):
name = self.name
super(ImageWithThumbsFieldFile, self).delete(save)
if self.sizes:
for size in self.sizes:
(w, h) = size
split = name.rsplit('.', 1)
thumb_name = '%s.%sx%s.%s' % (split[0], w, h, split[1])
try:
self.storage.delete(thumb_name)
except:
pass
class ImageWithThumbsField(ImageField):
attr_class = ImageWithThumbsFieldFile
"""
Usage example:
==============
photo = ImageWithThumbsField(upload_to='images', sizes=((125,125),(300,200),)
To retrieve image URL, exactly the same way as with ImageField:
my_object.photo.url
To retrieve thumbnails URL's just add the size to it:
my_object.photo.url_125x125
my_object.photo.url_300x200
Note: The 'sizes' attribute is not required. If you don't provide it,
ImageWithThumbsField will act as a normal ImageField
How it works:
=============
For each size in the 'sizes' atribute of the field it generates a
thumbnail with that size and stores it following this format:
available_filename.[width]x[height].extension
Where 'available_filename' is the available filename returned by the storage
backend for saving the original file.
Following the usage example above: For storing a file called "photo.jpg" it saves:
photo.jpg (original file)
photo.125x125.jpg (first thumbnail)
photo.300x200.jpg (second thumbnail)
With the default storage backend if photo.jpg already exists it will use these filenames:
photo_.jpg
photo_.125x125.jpg
photo_.300x200.jpg
Note: django-thumbs assumes that if filename "any_filename.jpg" is available
filenames with this format "any_filename.[widht]x[height].jpg" will be available, too.
To do:
======
Add method to regenerate thubmnails
"""
preview_width_field = None
preview_height_field = None
def __init__(self, verbose_name=None, name=None, width_field=None,
height_field=None, sizes=None,
preview_width_field=None, preview_height_field=None,
**kwargs):
self.verbose_name = verbose_name
self.name = name
self.width_field = width_field
self.height_field = height_field
self.sizes = sizes
super(ImageField, self).__init__(**kwargs)
if sizes is not None and len(sizes) == 1:
self.preview_width_field = preview_width_field
self.preview_height_field = preview_height_field
def update_dimension_fields(self, instance, force=False, *args, **kwargs):
"""
Update original image dimension fields and thumb dimension fields
(only if 1 thumb size is defined)
"""
super(ImageWithThumbsField, self).update_dimension_fields(instance,
force, *args,
**kwargs)
thumb_width_field = self.preview_width_field
thumb_height_field = self.preview_height_field
if thumb_width_field is None or thumb_height_field is None \
or len(self.sizes) != 1:
return
original_width = getattr(instance, self.width_field)
original_height = getattr(instance, self.height_field)
if original_width > 0 and original_height > 0:
thumb_width, thumb_height = self.sizes[0]
w_scale = float(thumb_width) / original_width
h_scale = float(thumb_height) / original_height
scale_ratio = min(w_scale, h_scale)
if scale_ratio >= 1:
thumb_width_ratio = original_width
thumb_height_ratio = original_height
else:
thumb_width_ratio = int(original_width * scale_ratio)
thumb_height_ratio = int(original_height * scale_ratio)
setattr(instance, thumb_width_field, thumb_width_ratio)
setattr(instance, thumb_height_field, thumb_height_ratio)