A filter to resize a ImageField on demand, a use case could be:
<img src="object.get_image_url" alt="original image">
<img src="object.image|thumbnail" alt="image resized to default 200x200 format">
<img src="object.image|thumbnail:"200x300" alt="image resized to 200x300">
The filter is applied to a image field (not the image url get from get_image_url method of the model), supposing the image filename is "image.jpg", it checks if there is a file called "image_200x200.jpg" or "image_200x300.jpg" on the second case, if the file isn't there, it resizes the original image, finally it returns the proper url to the resized image.
There is a TODO: the filter isn't checking if the original filename is newer than the cached resized image, it should check it and resize the image again in this case.
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import os import Image from django.template import Library register = Library() def thumbnail(file, size='200x200'): # defining the size x, y = [int(x) for x in size.split('x')] # defining the filename and the miniature filename basename, format = file.rsplit('.', 1) miniature = basename + '_' + size + '.' + format miniature_filename = os.path.join(settings.MEDIA_ROOT, miniature) miniature_url = os.path.join(settings.MEDIA_URL, miniature) # if the image wasn't already resized, resize it if not os.path.exists(miniature_filename): print '>>> debug: resizing the image to the format %s!' % size filename = os.path.join(settings.MEDIA_ROOT, file) image = Image.open(filename) image.thumbnail([x, y]) # generate a 200x200 thumbnail image.save(miniature_filename, image.format) return miniature_url register.filter(thumbnail)
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