def _get_thumbnail_filename(self, source, geometry_string, options):###customization
        """
        Computes the destination filename.
        """
        try:
            root_path = source.storage.path('')
        except: 
            #some storage backends do not support path() 
            root_path = ''
        split_path = re.sub(r'^%s%s?' % (root_path, os.sep), '', source.name).split(os.sep)
        split_path.insert(-1, geometry_string)

        #make some subdirs to avoid putting too many files in a single dir. 
        key = tokey(source.key, geometry_string, serialize(options))
        split_path.insert(-1, key[:2])
        split_path.insert(-1, key[2:4])

        #attempt to slugify the filename to make it SEO-friendly
        split_name = split_path[-1].split('.')
        try:
            split_path[-1] = '%s.%s' % (slugify('.'.join(split_name[:-1])), split_name[-1])
        except:
            #on fail keep the original filename
            pass
        
        path = os.sep.join(split_path)
        
        #if the path already starts with THUMBNAIL_PREFIX do not concatenate the PREFIX
        #this way we avoid ending up with a url like /images/images/120x120/my.png
        if not path.startswith(settings.THUMBNAIL_PREFIX):
            return '%s%s' % (settings.THUMBNAIL_PREFIX, path) 
        
        return path

 def _get_thumbnail_filename(self, source, geometry_string, options):
     """
     Computes the destination filename.
     """
     key = tokey(serialize(options))
     image_path = os.path.relpath(source.url, source.storage.location)
     path = '%s-%s-%s' % (os.path.splitext(image_path)[0], geometry_string, key)
     return '%s%s.%s' % (settings.THUMBNAIL_PREFIX, path, EXTENSIONS[options['format']])

 def _get_thumbnail_filename(self, source, geometry_string, options):
     """
     Computes the destination filename.
     """
     key = tokey(source.key, geometry_string, serialize(options))
     # make some subdirs
     path = "%s/%s/%s" % (key[:2], key[2:4], key)
     return "%s%s.%s" % (settings.THUMBNAIL_PREFIX, path, self.extensions[options["format"]])

    def _get_thumbnail_filename(self, source, geometry_string, options):
        """
        Computes the destination filename.
        """
        # HACK: preserving output format of the image
        if options.get('format', 'auto') == 'auto':
            options['format'] = guess_image_format(source.name)

        key = tokey(source.key, geometry_string, serialize(options))
        # make some subdirs
        path = '%s/%s/%s' % (key[:2], key[2:4], key)
        return '%s%s.%s' % (settings.THUMBNAIL_PREFIX, path,
                            EXTENSIONS[options['format']])

    def _get_thumbnail_filename(self, source, geometry_string, options):
        """
        Computes the destination filename.
        """
        key = tokey(source.key, geometry_string, serialize(options))

        filename, _ext = os.path.splitext(os.path.basename(source.name))

        cache_path = '{}/{}/{}'.format(key[:2], key[2:4], key)

        filename = '{prefix}{cache_path}/{filename}.{ext}'.format(
            prefix=settings.THUMBNAIL_PREFIX,
            cache_path=cache_path,
            filename=filename,
            ext=EXTENSIONS[options['format']],
        )
        return filename

 def _get_thumbnail_filename(self, source, geometry_string, options):
     key = tokey(source.key, geometry_string, serialize(options))
     path = '%s/%s/%s' % (key[:2], key[2:4], key)
     return '%s%s/%s' % (settings.THUMBNAIL_PREFIX, path, basename(source.name))

 def key(self):
     return tokey(self.name, self.serialize_storage())

def get_minecraft_avatar(minecraft_user, geometry_string, force=True):
    """
    This method uses the sorl-thumbnail cache backend to
    prevent images from being downloaded every time.
    It requires an username.
    """
    avatar_file = UploadedFile(
        file=StringIO(),
        name='%s/%s.png' % (settings.MEDIA_ROOT, tokey(minecraft_user)))

    try:
        # Check if the avatar is cached
        thumbnail = get_thumbnail(
            avatar_file, '100x100', quality=100, format='PNG')
    except IOError:
        download_thumbnail = True

    else:
        is_dummy = not hasattr(thumbnail, 'storage')
        if not is_dummy and not thumbnail.storage.exists(thumbnail.name):
            # It seems we have the avatar on cache (kvstore)
            # but it's not present on the storage
            download_thumbnail = True
            # Force remove thumbnail from kvstore
            sorl_default.kvstore.delete(thumbnail)
            # Log
            logger.warning('Avatar cache mismatch: %s (resetting)' % (
                minecraft_user,))
        else:
            logger.debug('Avatar fetched from cache: %s' % minecraft_user)
            download_thumbnail = False

    if download_thumbnail:
        logger.debug('Downloading avatar: %s' % minecraft_user)

        # Otherwise download avatar
        thumbnail = None

        try:
            skin_bin = requests.get(
                'http://s3.amazonaws.com/MinecraftSkins/%s.png' % (
                    minecraft_user
                )
            ).content
        except ConnectionError:
            return None

        try:
            skin = Image.open(StringIO(skin_bin)).convert('RGBA')
        except IOError:
            # Image not found or some permission error with S3
            if minecraft_user != 'char':
                if not force:
                    return None
                # Return default user avatar
                return settings.STATIC_URL + settings.DEFAULT_USER_AVATAR
        else:
            face = skin.crop((8, 8, 16, 16))
            accessories = skin.crop((40, 8, 48, 16))

            r, g, b, a = accessories.split()

            accessories = Image.merge('RGB', (r, g, b))
            mask = Image.merge('L', (a,))

            face.paste(accessories, (0, 0), mask)

            avatar = face.resize((135, 135))

            avatar.save(avatar_file, 'PNG')

            avatar_file.seek(0)

            # Save through sorl backend
            thumbnail = get_thumbnail(avatar_file, '100x100',
                                      quality=100, format='PNG')

    # Use the cached file
    return get_thumbnail(thumbnail, geometry_string,
                         quality=100, format='PNG').url

 def key(self):
     if not hasattr(self, "_key"):
         self._key = tokey(self.name, self.serialize_storage())
     return self._key

    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.
        """
        logger.debug('Getting thumbnail for file [%s] at [%s]', file_, geometry_string)

        source = ImageFile(file_)

        # preserve image filetype
        if settings.THUMBNAIL_PRESERVE_FORMAT:
            options.setdefault('format', self._get_format(source))

        for key, value in self.default_options.items():
            options.setdefault(key, value)

        # For the future I think it is better to add options only if they
        # differ from the default settings as below. This will ensure the same
        # filenames being generated for new options at default.
        for key, attr in self.extra_options:
            value = getattr(settings, attr)
            if value != getattr(default_settings, attr):
                options.setdefault(key, value)

        name = self._get_thumbnail_filename(source, geometry_string, options)
        thumbnail = ImageFile(name, default.storage, key=tokey(source.key, geometry_string, serialize(options)))
        cached = default.kvstore.get(thumbnail)

        if cached:
            return cached

        # We have to check exists() because the Storage backend does not
        # overwrite in some implementations.
        if settings.THUMBNAIL_FORCE_OVERWRITE or not thumbnail.exists():
            try:
                source_image = default.engine.get_image(source)
            except IOError as e:
                logger.exception(e)
                if settings.THUMBNAIL_DUMMY:
                    return DummyImageFile(geometry_string)
                else:
                    # if S3Storage says file doesn't exist remotely, don't try to
                    # create it and exit early.
                    # Will return working empty image type; 404'd image
                    logger.warning(
                        'Remote file [%s] at [%s] does not exist',
                        file_, geometry_string,
                    )
                    return thumbnail

            
            # We might as well set the size since we have the image in memory
            image_info = default.engine.get_image_info(source_image)
            options['image_info'] = image_info
            size = default.engine.get_image_size(source_image)
            source.set_size(size)

            try:
                self._create_thumbnail(source_image, geometry_string, options,
                                       thumbnail)
                self._create_alternative_resolutions(source_image, geometry_string,
                                                     options, thumbnail.name)
            finally:
                default.engine.cleanup(source_image)


        # If the thumbnail exists we don't create it, the other option is
        # to delete and write but this could lead to race conditions so I
        # will just leave that out for now.
        default.kvstore.get_or_set(source)
        default.kvstore.set(thumbnail, source)
        return thumbnail

 def _generate_thumbnail_url_cache_key(self, file_, size):
     source = ImageFile(file_)
     key = "thumbnail_url_%s" % (tokey(source.key, size))
     return key