Workaround to prevent thumbnail creation for GIFs

[wfehr]

Since a solution to preserve animations on GIFs is a bit tricky I made a little workaround to prevent thumbnail creaton for GIFs.

Issues for this problem: #184 and #217

[jrief]

I would rather use

Suggested change

	if settings.THUMBNAIL_PREVENT_GIF_CONVERT and '.gif' in source.url:
	bits = os.path.splitext(source.url)
	if settings.THUMBNAIL_PREVENT_GIF_CONVERT and bits[1] == '.gif':

to explicitly state what's the intention.

[wfehr]

Thanks for the quick review! I just pushed it with that changes.

Edit: Forgot about the tests, trying to fix that.
Edit2: I changed the piece of code so tests are running again.
Don't really understand why this

117             bits = os.path.splitext(getattr(source, 'url', source.name))
118             if settings.THUMBNAIL_PREVENT_GIF_CONVERT and bits[1] == '.gif':

is a reason for some tests to fail.

[wfehr]

Any news on a possible release date?

[jrief]

You wrote:

Since a solution to preserve animations on GIFs is a bit tricky I made a little workaround to prevent thumbnail creation for GIFs.

Is there any way to detect, if a gif has animations? What kind of errors happen, if Pillow creates a thumbnail from an animated gif.

[wfehr]

Is there any way to detect, if a gif has animations? What kind of errors happen, if Pillow creates a thumbnail from an animated gif.

Sorry for the misunderstanding: I didn't really try out how to solve the problem myself. I wrote this based on the comments in the above mentioned issues.
What I meant is, if this workaround is going to be released?

[jrief]

For me it seems to solve a problem, which is too specific to one use-case.
If this is really a problem for animated GIFs, then I would apply it only this class of images.

[Akiat]

Really interested by this PR. I need to preserve GIF animation and it would be great to have this in the release.

Edit: I tried it, but the animation isn't preserved in my case.