Sky Thumbnails is an open-source Django library developed by Concentric Sky. It provides a model field, EnhancedImageField, which adds thumbnail support to the default ImageField.
pip install git+https://github.com/concentricsky/django-skythumbnails.git
Add the following to your settings.py:
INSTALLED_APPS = [
...
'sky_thumbnails',
...
]
To change the quality of JPEG thumbnails (default is 85):
THUMBNAILS_QUALITY = 95
To create PNG thumbnails instead of JPEG:
THUMBNAILS_FORMAT = 'PNG'
Thumbnails are generated when the EnhancedImageField is saved. To generate missing thumbnails on request:
THUMBNAILS_DELAYED_GENERATION = True
Thumbnails will be saved in a directory relative to the ImageField's upload_to value. By default, the directory will be named 'thumbs'. To change the directory's name:
THUMBNAILS_DIRNAME = 'thumbnails'
The following code snippet illustrates how to use the EnhancedImageField::
from django.db import models
from sky_thumbnails.fields import EnhancedImageField
class MyModel(models.Model):
photo = EnhancedImageField(
verbose_name='Icon for the Services index page',
upload_to = 'uploads/technology',
process_source = dict(size=(300,600)),
thumbnails = {
'icon': dict(size=(30,60)),
}
)
The following code snippet illustrates how to print an EnhancedImageField in a
Jinja2 template. Note, we are checking to make sure the image exists before
calling the url property. The url property appends the STATIC_URL to the path
of the image::
{% if object.photo %}
<img src="{{object.photo.url}}" alt="Full image" />
{% if object.photo.icon %}
<img src="{{object.photo.icon.url}} alt="Small image" />
{% endif %}
{% endif %}
The EnhancedImageField derives from the default ImageField and thus all attributes and methods of the default ImageField are inherited.
In addition to the default arguments, the EnhancedImageField also supports the following:
process_source
A dictionary of image processing options. The same options, that can be used for the thumbnail generation, can also be set in this attribute. If this is set, the original image will be processed using the provided options before it is saved on the remote server. Contrariwise, if this attribute is not set or set to None, the uploaded image is saved in its original form, without any further processing. It should be noted that setting this attribute to an empty dictionary still causes the source image to be processed using default image processing options. This practically means that the source image will be saved in the format specified by the THUMBNAILS_FORMAT setting without any resizing or filtering taking place.
thumbnails
A dictionary of thumbnail definitions. The format of each thumbnail definition is::
<thumbnail_identifier> : <image_processing_options>
thumbnail_identifier
Is a string that uniquely identifies the thumbnail. It is required that all thumbnails use a unique identifier. This identifier is used in the thumbnail access mechanism and is also used in the generated filename of the thumbnail image file.
image_processing_options
This is a dictionary of options that will be used during the thumbnail generation. This dictionary must be present on every thumbnail definition. Any of the following supported options may be used:
size
A tuple which represents the size of the generated thumbnail.
sharpen
Boolean option. If set, the ImageFilter.SHARPEN filter will be applied to the thumbnail.
detail
Boolean option. If set, the ImageFilter.DETAIL filter will be applied to the thumbnail.
upscale
Boolean option. By default, image resizing occurs only if any of the source image dimensions is bigger than the dimension indicated by the size option. If the upscale option is set to True, resizing occurs even if the generated thumbnail is bigger than the source image.
format
This is the format in which the thumbnail should be saved.
Valid values are those supported by the Python Imaging Library (PIL). If it is not set, then the default format specified by the THUMBNAILS_FORMAT setting will be used. In case the format is set to JPEG, the value of the THUMBNAILS_QUALITY is used as the quality when the image is saved.
This project is licensed under the Apache License, Version 2.0. Details can be found in the LICENSE.md file.
For copyright and other important notes regarding this release please read the AUTHORS.md file.
For nearly a decade, Concentric Sky has been building technology solutions that impact people everywhere. We work in the mobile, enterprise and web application spaces. Our team, based in Eugene Oregon, loves to solve complex problems. Concentric Sky believes in contributing back to our community and one of the ways we do that is by open sourcing our code on GitHub. Contact Concentric Sky at [email protected].