django-imagekit

photos.models.py

from django.db import models
from django.contrib.auth.models import User

from imagekit.models import ImageSpec
from imagekit.processors import resize, Adjust

from django.db.models.signals import post_save
from django.dispatch import receiver
from celery.task import task
from celery.execute import send_task

from base64 import urlsafe_b64encode
from hashlib import sha512
from os import urandom
from time import time

def imagefield_upload_to(instance, filename):
	dir = 'photos/o/'
	time_hash = urlsafe_b64encode(sha512(str(time())).digest())[:20:]
	random_key = urlsafe_b64encode(sha512(urandom(100)).digest())[:5:]
	extension = filename.split('.')[-1::].pop()
	return dir + time_hash + random_key + '.' + extension

class Photo(models.Model):
	user = models.ForeignKey(User)
	title = models.CharField(max_length = 100, blank=True)
	description = models.TextField(blank=True)
	is_active = models.BooleanField(default=False)
	original_image = models.ImageField(upload_to = imagefield_upload_to)

	small_thumbnail = ImageSpec(
		processors = [
			resize.Crop(width=100, height=100),
			Adjust(sharpness=1.2),
		],
		image_field = 'original_image',
		format = 'JPEG',
		quality = 85,
		cache_to = 'photos/st',
	)

	large_thumbnail = ImageSpec(
		processors = [
			resize.Crop(width=200, height=200),
			Adjust(sharpness=1.2),
		],
		image_field = 'original_image',
		format = 'JPEG',
		quality = 85,
		cache_to = 'photos/lt',
	)

	large_image = ImageSpec(
		processors = [
			resize.Fit(width=1024, height=1024),
			Adjust(sharpness=1.2),
		],
		image_field = 'original_image',
		format = 'JPEG',
		quality = 85,
		cache_to = 'photos/l',
	)

	medium_image = ImageSpec(
		processors = [
			resize.Fit(width=640, height=640),
			Adjust(sharpness=1.2),
		],
		image_field = 'original_image',
		format = 'JPEG',
		quality = 85,
		cache_to = 'photos/m',
	)

	small_image = ImageSpec(
		processors = [
			resize.Fit(width=240, height=240),
			Adjust(sharpness=1.2),
		],
		image_field = 'original_image',
		format = 'JPEG',
		quality = 85,
		cache_to = 'photos/s',
	)

	def __unicode__(self):
		return u'%s by %s' % (self.title, self.user.username)

@task(name="photos.models.generate_resized_images")
def generate_resized_images(primary_key):
	from photos.models import Photo
	try:
		instance = Photo.objects.get(id=primary_key)
		instance.small_thumbnail._create()
		instance.large_thumbnail._create()
		instance.small_image._create()
		instance.medium_image._create()
		instance.large_image._create()
		print 'success!'
	except:
		print 'couldn\'t resize images :/'

@receiver(post_save, sender=Photo)
def photo_postsave_handler(sender, instance, created, raw, **kwargs):
	if created == True:
		send_task("photos.models.generate_resized_images", [instance.id])

settings.py

INSTALLED_APPS = (
	'django.contrib.auth',
	'django.contrib.contenttypes',
	'django.contrib.sessions',
	'django.contrib.sites',
	'django.contrib.messages',
	'django.contrib.staticfiles',

	'django.contrib.admin',
	'django.contrib.admindocs',

	'imagekit',
	'djcelery',

	'pages',
	'photos',
	'themes',
	'users',
)

# Celery (For delayed jobs)
BROKER_HOST = "127.0.0.1"
BROKER_BACKEND="redis"
REDIS_PORT=6379
REDIS_HOST = "127.0.0.1"
BROKER_USER = ""
BROKER_PASSWORD =""
BROKER_VHOST = "0"
REDIS_DB = 0
REDIS_CONNECT_RETRY = True
CELERY_SEND_EVENTS = True
CELERY_RESULT_BACKEND = 'redis'
CELERY_TASK_RESULT_EXPIRES =  10
CELERYBEAT_SCHEDULER = "djcelery.schedulers.DatabaseScheduler"

import djcelery
djcelery.setup_loader()