Format Preservation with minimal alterations

README.rst

@@ -1,20 +1,13 @@
-sorl-thumbnail
-==============
+django-thumbnail
+================
 
-Thumbnails for Django. Totally rewritten.
+A fork of sorl-thumbnail; created due to its inactivity.
 
-Features at a glance
---------------------
-- Storage support
-- Pluggable Engine support (ImageMagick, PIL, pgmagick included)
-- Pluggable Key Value Store support (cached db, redis)
-- Pluggable Backend support
-- Admin integration with possibility to delete
-- Dummy generation (placeholders)
-- Flexible, simple syntax, generates no html
-- ImageField for model that deletes thumbnails
-- CSS style cropping options
-- Margin calculation for vertical positioning
+pip install django-thumbnail
 
-Read more in `the documentation (latest version) <http://sorl-thumbnail.rtfd.org/>`_
+---------------------------------------------------------
 
+
+Format preservation has been added. To preserve format set settings.THUMBNAIL_PRESERVE_FORMAT = True.
+Gracefully degrades and defaults to using settings.THUMBNAIL_FORMAT.
+Applications that currently use sorl should not notice any difference in functionality unless settings.THUMBNAIL_PRESERVE_FORMAT is set explicitly set to True.

setup.py

@@ -10,14 +10,14 @@ def run(self):
 
 
 setup(
-    name='sorl-thumbnail',
+    name='django-thumbnail',
     version=sorl.__version__,
-    description='Thumbnails for Django',
+    description='Thumbnailing in Django',
     long_description=open('README.rst').read(),
-    author='Mikko Hellsing',
-    author_email='mikko@aino.se',
+    author='Clinton Christian',
+    author_email='pygeek@me.com',
     license='BSD',
-    url='https://github.com/sorl/sorl-thumbnail',
+    url='https://github.com/pygeek/django-thumbnail',
     packages=find_packages(exclude=['tests', 'tests.*']),
     platforms='any',
     zip_safe=False,

sorl/thumbnail/base.py

@@ -1,3 +1,5 @@
+import re
+
 from sorl.thumbnail.conf import settings, defaults as default_settings
 from sorl.thumbnail.helpers import tokey, serialize
 from sorl.thumbnail.images import ImageFile
@@ -16,6 +18,7 @@ class ThumbnailBackend(object):
     The main class for sorl-thumbnail, you can subclass this if you for example
     want to change the way destination filename is generated.
     """
+
     default_options = {
         'format': settings.THUMBNAIL_FORMAT,
         'quality': settings.THUMBNAIL_QUALITY,
@@ -29,13 +32,35 @@ class ThumbnailBackend(object):
         ('orientation', 'THUMBNAIL_ORIENTATION'),
     )
 
+    file_extension = lambda inst, file_: str(file_).split('.')[-1].lower()
+
+    def _get_format(self, file_):
+        file_extension = self.file_extension(file_)
+
+        is_jpeg = re.match('jpg|jpeg', file_extension)
+        is_png = re.match('png', file_extension)
+
+        if is_jpeg:
+            format_ = 'JPEG'
+        elif is_png:
+            format_ = 'PNG'
+        else:
+            format_ = default_settings.THUMBNAIL_FORMAT
+
+        return str(format_)
+
     def get_thumbnail(self, file_, geometry_string, **options):
         """
         Returns thumbnail as an ImageFile instance for file with geometry and
         options given. First it will try to get it from the key value store,
         secondly it will create it.
         """
         source = ImageFile(file_)
+
+        #preserve image filetype
+        if settings.THUMBNAIL_PRESERVE_FORMAT:
+            self.default_options['format'] = self._get_format(file_)
+
         for key, value in self.default_options.iteritems():
             options.setdefault(key, value)
         # For the future I think it is better to add options only if they

sorl/thumbnail/conf/defaults.py

@@ -51,6 +51,8 @@
 # Make sure the backend can handle the format you specify
 THUMBNAIL_FORMAT = 'JPEG'
 
+THUMBNAIL_PRESERVE_FORMAT = False
+
 # Colorspace, backends are required to implement: RGB, GRAY
 # Setting this to None will keep the original colorspace.
 THUMBNAIL_COLORSPACE = 'RGB'