django-image-cropping 0.5

A reusable app for cropping images easily and non-destructively in Django

django-image-cropping is an app for cropping uploaded images via Django’s admin backend using imgareaselect. It keeps the original image intact, only cropping when the image is being displayed. Large images are presented in a small format, so even very big images can easily be cropped.

django-image-cropping is perfect when you need images with a specific size for your templates but want your users or editors to upload images of any dimension. It presents a selection with a fixed aspect ratio so your users can’t break the layout with oddly-sized images.

It provides the necessary fields, widgets and a (easy_thumbnails) thumbnail processor for displaying the cropped image in your templates. Also works with FeinCMS content types!

Screenshot:

Installation

1. Install django-image-cropping using pip. For example:

   pip install django-image-cropping

2. Add easy_thumbnails and image_cropping to your INSTALLED_APPS. image_cropping is only required if you are using Django 1.3 and contrib.staticfiles

3. Adjust the thumbnail processors for easy_thumbnails in your settings.py:

   from easy_thumbnails.conf import settings as thumbnail_settings
   THUMBNAIL_PROCESSORS = (
       'image_cropping.thumbnail_processors.crop_corners',
   ) + thumbnail_settings.THUMBNAIL_PROCESSORS

4. Deploy the necessary static files. If you are using Django 1.3 and contrib.staticfiles the necessary static files should be picked up automatically. In all other cases you have to copy or symlink the static files. Depending on your setup the command should look similiar to this:

   ln -s ~/.virtualenvs/yourenv/src/django-image-cropping/image_cropping/static/image_cropping/

Configuration

In order to make a regular ImageField croppable, simply turn it into an ImageCropField. Then add an ImageRatioField, which will contain the boundaries of the cropped image. The ImageRatioField expects the name of the associated ImageCropField as the first argument and the size of the final image to be displayed as the second argument.

The size is passed in as a string and defines the aspect ratio of the selection as well as the minimum size for the final image. You can configure a warning if users try to crop a selection smaller than this size (see below).

1. Model fields and options:

   from image_cropping.fields import ImageRatioField, ImageCropField
   
   image = ImageCropField(blank=True, null=True, upload_to='uploaded_images')
   # size is "width x height"
   cropping = ImageRatioField('image', '430x360')

2. If your setup is correct you should automatically see the enhanced image widget that provides a selection area for the image in the admin backend.

3. Example usage of the thumbnail processor:

   {% thumbnail yourmodel.image 430x360 box=yourmodel.cropping crop detail %}

4. Additionally you can define the maximum size of the preview thumbnail in your settings.py:

   # size is "width x height"
   IMAGE_CROPPING_THUMB_SIZE = (300, 300)

5. You can warn users about crop selections that are smaller than the size defined in the ImageRatioField. When users try to do a smaller selection, a red border appears around the image. To use this functionality, add the parameter to the ImageRatioField:

   cropping = ImageRatioField('image', '430x360', size_warning=True)

   You can enable this functionality project-wide by adding the following line to your settings file:

   IMAGE_CROPPING_SIZE_WARNING = True

Extras

If you need the same image in multiple formats, simply specify another ImageRatioField. This will allow the image to be cropped twice:

from image_cropping.fields import ImageRatioField, ImageCropField

image = ImageCropField(blank=True, null=True, upload_to='uploaded_images')
# size is "width x height"
list_page_cropping = ImageRatioField('image', '200x100')
detail_page_cropping = ImageRatioField('image', '430x360')

In your templates, use the corresponding ratio field:

{% thumbnail yourmodel.image 200x100 box=yourmodel.list_page_cropping crop detail %}

If you need to crop an image contained within another model, referenced by a ForeignKey, use a CropForeignKey. This field works like a regular ForeignKey but expects a keyword argument named field_name. The model attribute with this name needs to be an ImageField that will be cropped:

from django.db import models
from image_cropping.fields import ImageRatioField, CropForeignKey

class Image(models.Model):
    image_field = models.ImageField(upload_to='image/')

class NewsItem(models.Model):
    title = models.CharField(max_length=255)
    image = CropForeignKey(Image, 'image_field')
    cropping = ImageRatioField('image', '120x100')

The CropForeignKey works only in the admin for now, as it uses the raw_id widget.

If you want cropping to be optional, just use allow_fullsize=True as an additional keyword argument in your ImageRatioField. It should now be possible to switch off cropping by unchecking the checkbox next to the image cropping widget.