A reusable app for cropping images easily and non-destructively in Django
Project description
django-image-cropping is an app for cropping uploaded images via Django’s admin backend using Jcrop. 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
Install django-image-cropping using pip. For example:
pip install django-image-cropping
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 or want to use the image_cropping templatetag.
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_PROCESSORSDeploy 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 similar to this:
ln -s ~/.virtualenvs/yourenv/src/django-image-cropping/image_cropping/static/image_cropping/
Configuration
To your model containing an ImageField, 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).
Model fields and options:
from django.db import models from image_cropping import ImageRatioField class MyModel(models.Model): image = models.ImageField(blank=True, null=True, upload_to='uploaded_images') # size is "width x height" cropping = ImageRatioField('image', '430x360')In your admin class, add the ImageCroppingMixin in order to see the cropping widget:
from django.contrib import admin from image_cropping import ImageCroppingMixin class MyModelAdmin(ImageCroppingMixin, admin.ModelAdmin): pass admin.site.register(MyModel, MyModelAdmin)If your setup is correct you should now see the enhanced image widget that provides a selection area for the image in the admin backend.
Additionally, you can define the maximum size of the preview thumbnail in the admin in your settings.py:
# size is "width x height" IMAGE_CROPPING_THUMB_SIZE = (300, 300)
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.py:
IMAGE_CROPPING_SIZE_WARNING = True
Frontend
For your frontend code, django-image-cropping provides a templatetag to use for displaying a cropped thumbnail:
{% cropped_thumbnail yourmodelinstance "ratiofieldname" [scale=INT|width=INT|height=INT] [upscale] %}
Example usage:
{% load cropping %}
<img src="{% cropped_thumbnail yourmodel "cropping" scale=0.5 %}">
You can also use the standard easy_thumbnails templatetag with the “box” parameter:
{% load thumbnails %}
{% thumbnail yourmodel.image 430x360 box=yourmodel.cropping crop detail %}
Or generate the URL from Python code in your view:
from easy_thumbnails.files import get_thumbnailer
thumbnail_url = get_thumbnailer(yourmodel.image).get_thumbnail({
'size': (430, 360),
'box': yourmodel.cropping,
'crop': True,
'detail': True,
}).url
Cropping from a ModelForm
If you want to use the cropping widget outside the admin, you’ll need to define the ImageField as an ImageCropField:
from django.db import models
from image_cropping import ImageCropField, ImageRatioField
class MyModel(models.Model):
image = ImageCropField(blank=True, null=True, upload_to='uploaded_images')
# size is "width x height"
cropping = ImageRatioField('image', '430x360')
Alternatively, override the widget in your ModelForm (you just need to do one of these two, not both!):
from django import forms
from image_cropping import ImageCropWidget
class MyModelForm(forms.ModelForm):
class Meta:
widgets = {
'image': ImageCropWidget,
}
Remember to include the form media in the <head> of your HTML:
<html>
<head>
{{ form.media }}
</head>
<body>
{{ form }}
</body>
</html>
The cropping itself happens in the ImageRatioField, the ImageCropField will still be a regular file upload. If you’re selectively including or excluding fields from the ModelForm, remember to include the ImageRatioField.
Extras
Multiple formats
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 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:
{% load cropping %}
{% cropped_thumbnail yourmodel list_page_cropping %}
Foreign Keys
If you need to crop an image contained within another model, referenced by a ForeignKey, the ImageRatioField is composed of the ForeignKey name, double underscore, and the ImageField name:
from django.db import models
from image_cropping.fields import ImageRatioField
class Image(models.Model):
image_field = models.ImageField(upload_to='image/')
class NewsItem(models.Model):
title = models.CharField(max_length=255)
image = models.ForeignKey(Image)
cropping = ImageRatioField('image__image_field', '120x100')
Cropping foreign keys works only in the admin for now, as it uses the raw_id widget.
Disabling cropping
If you want cropping to be optional, use allow_fullsize=True as an additional keyword argument in your ImageRatioField. Editors can now switch off cropping by unchecking the checkbox next to the image cropping widget.
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