Fixed a number of issues with the changes to fetchart:
- Remove redundant fetches. This was making the Amazon source download every
image twice even when art resizing was not enabled!
- Restore local_only switch in plugin hook, which got lost in the shuffle at
some point.
- Don't replace the original image file in-place; use a temporary file instead.
This would clobber the original source image on the filesystem with the
downscaled version!
The previous method was to change self.__class__ dynamically to make __init__
instantiate different classes. This new way, which uses bare functions instead
of separate functor-like classes, instead just forwards the resize() call to
a module-global implementation based on self.method.
Additionally, the semantics of ArtResizer have changed. Clients now *always*
call resize() and proxy_url(), regardless of method. The method makes *one* of
these a no-op. This way, clients need not manually inspect which method is
being used.
artresizer.py instances an ArtResizer object that uses internally the PIL; ImageMagick
or a web proxy service to perform the resizing operations.
Because embedart works on input images located on filesystem it requires PIL or ImageMagick, whereas
fetchart is able to do the job with the fallback webproxy resizer.
This necessitated a slight refactoring in the plugin event handling mechanism.
Rather than loading all handlers up front and storing them in a module-scope
structure, we now scan for event handlers at every send(). This is probably
very slightly less efficient but allows for more flexible logic.
