Versions

With the FileBrowser, you are able to define different versions/sizes for images. This enables you to save an original image on your server while having different versions of that image to automatically fit your websites grid. Versions are also useful for responsive/adaptive layouts.

To generate a version of a source image, you specify options which are used by the image processors (see VERSION_PROCESSORS) to generate the required version.

Defining Versions

First you need to know which versions/sizes of an image you’d like to generate with your website. Let’s say you’re using a 12 column grid with 60px for each column and 20px margin (which is a total of 940px). With this grid, you could (for example) define these image VERSIONS:

FILEBROWSER_VERSIONS_BASEDIR = '_versions'
FILEBROWSER_VERSIONS = {
  'admin_thumbnail': {'verbose_name': 'Admin Thumbnail', 'width': 60, 'height': 60, 'opts': 'crop'},
  'thumbnail': {'verbose_name': 'Thumbnail (1 col)', 'width': 60, 'height': 60, 'opts': 'crop'},
  'small': {'verbose_name': 'Small (2 col)', 'width': 140, 'height': '', 'opts': ''},
  'medium': {'verbose_name': 'Medium (4col )', 'width': 300, 'height': '', 'opts': ''},
  'big': {'verbose_name': 'Big (6 col)', 'width': 460, 'height': '', 'opts': ''},
  'large': {'verbose_name': 'Large (8 col)', 'width': 680, 'height': '', 'opts': ''},
}

Use the methods argument, if you need to add a filter:

def grayscale(im):
    "Convert image to grayscale"
    if im.mode != "L":
        im = im.convert("L")
    return im

FILEBROWSER_VERSIONS = {
    'big': {'verbose_name': 'Big (6 col)', 'width': 460, 'height': '', 'opts': '', 'methods': [grayscale]},
})

Custom processors

New in version 3.7.2.

Custom processors can be created using a simple method like this:

def grayscale_processor(im, grayscale=False, **kwargs):
    if grayscale:
        if im.mode != "L":
            im = im.convert("L")
    return im

The first argument for a processor is the source image.

All other arguments are keyword arguments which relate to the list of options received from the version_generate method.

Ensure that you explicitly declare all params that could be used by your processor, as the processors arguments can be inspected to get a list of valid options.

In order to turn your processor optional, define the params that your processor expects with a falsy default, and in this case you could return the original image without any modification.

You must also use **kwargs at the end of your argument list because all options used to generate the version are available to all processors, not just the ones defined in your processor.

Whether a processor actually modifies the image or not, they must always return an image.

Using the processor

Override the VERSION_PROCESSORS setting:

FILEBROWSER_VERSION_PROCESSORS = [
    'filebrowser.utils.scale_and_crop',
    'my_project.my_processors.grayscale_processor',
]

And in your versions definition:

FILEBROWSER_VERSIONS = {
    'big_gray': {'verbose_name': 'Big (6 col)', 'width': 460, 'grayscale': True},
})

Versions and the Admin

When using the FileBrowser with the admin interface, you need to define ADMIN_VERSIONS and ADMIN_THUMBNAIL (see Settings). ADMIN_VERSIONS are available with the admin, i.e. you are able to see these versions with the image detail view and you are able to select the versions with the FileBrowseField model field.

FILEBROWSER_ADMIN_VERSIONS = ['thumbnail', 'small', 'medium', 'big', 'large']
FILEBROWSER_ADMIN_THUMBNAIL = 'admin_thumbnail'

Versions and the Frontend

With the templatetag version a version will be generated if it doesn’t already exist OR if the original image is newer than the version. In order to update an image, you just overwrite the original image and the versions will be generated automatically (as you request them within your template).

A Model example:

from filebrowser.fields import FileBrowseField

class BlogEntry(models.Model):
    image = FileBrowseField("Image", max_length=200, blank=True, null=True)

With your templates, use version if you simply need to retrieve the URL or version as var if you need to get a FileObject:

<!-- load filebrowser templatetags -->
{% load fb_versions %}

<!-- get the url with version -->
<img src="{% version blogentry.image 'medium' %}" />

<!-- get a fileobject with version -->
{% version blogentry.image 'medium' as version_medium %}
{{ version_medium.width }}
<img src="{{ version_medium.url }}" />

Templatetag version

Retrieves/Generates a version and returns an URL:

{% version model.field_name version_prefix %}

Retrieves/Generates a version and returns a FileObject:

{% version model.field_name version_prefix as variable %}

Note

version_prefix can either be a string or a variable. If version_prefix is a string, use quotes.

Versions in Views

If you have a FileObject you can generate/retrieve a version with:

v = obj.image.version_generate(version_prefix) # returns a FileObject

Placeholder

When developing on a locale machine or a development-server, you might not have all the images (resp. media-files) available that are on your production instance and downloading these files on a regular basis might not be an option.

In that case, you can use a placeholder instead of a version. You just need to define the PLACEHOLDER and overwrite the settings SHOW_PLACEHOLDER and/or FORCE_PLACEHOLDER (see Placeholder).

Management Commands

fb_version_generate

If you need to generate certain (or all) versions, type:

python manage.py fb_version_generate
fb_version_remove

If you need to remove certain (or all) versions, type:

python manage.py fb_version_remove

Warning

Please be very careful with this command.