autodetect ImageMagick on windows

[Nex4rius]

Autodetect ImageMagick on windows

[coveralls]

Coverage decreased (-0.09%) to 67.306% when pulling 0560b70 on Nex4rius:patch-1 into 427c122 on Zulko:master.

[tburrows13]

Would someone else like to approve this PR?

[tburrows13]

Thanks for the contribution. However, I think that this has been superseded by #1109.

[Nex4rius]

I have to disagree.

I looked at #1109 and with that it checks for the ImageMagick environment variable and then uses that.
I just looked and after installing ImageMagick it didn't set the environment variable which means I still have to manually add it.

I still think it's better if it can autodetect it without configuring / setting environmental variables / doing anything.

Also this does no harm and is literally the last fallback if everything else fails.

[tburrows13]

Sorry, I think you're right, I had possibly misinterpreted #1109. I agree that this does additional processing that #1109 does not do.

You now need to run black over it with black -t py36 .. I'd also suggest using encoding="utf-8" in check_output instead of decoding the output.

[Nex4rius]

I added the encoding but what is that black -t py36 command?

Isn't that like less readable?

[tburrows13]

In cases like this, yes, it is arguably less useful, but overall it ensures that the style is consistent which is a great benefit (it was very bad before we started using it!) .

You can install it with pip install black, and then run black -t py36 . from the root directory of MoviePy. Thanks!

[tburrows13]

Hey, thanks for getting it sorted with black! Its a big help to have the code all formatted consistently (I know that yours was fine (just different in matters of taste) before, but a lot of contributions aren't and it is so much easier to run a single tool on a submission than it is to nitpick every little change.) For future reference it should be a one-line command and commit, it looks like you tried to do it manually? Either way, it's fine now.

I made a couple more smaller changes that I just noticed. @mgaitan was right about not using a bare except: https://stackoverflow.com/questions/54948548/what-is-wrong-with-using-a-bare-except. We don't want to catch things like KeyboardInterrupt or SystemExit.
And your code was giving warnings about invalid escape characters because it used backslashes in the string without marking it as raw with the r before it.

If you're happy with my changes, then I'm happy to merge!

[Nex4rius]

Sure looks fine now :)

[Nex4rius]

What exactly are we waiting for until merge?

[tburrows13]

Nothing, just all the maintainers are quite busy :) Commenting reminders every so often like you've done is a good idea.

[tburrows13]

Are you using image magick 6 or 7? I notice that this uses convert.exe which I think is IM6 only? Is there a reason why it shouldn't be changed to magick.exe for IM7?

[Nex4rius]

I have imagemagick 7 and it has both convert.exe and magick.exe