Update preview.py, fix issue #575

[Victrollia]

Fixed issue #575. Added two pg.quit statements at lines 146 and 162. For line 146, this statement adds quit functionality for " event.type == pg.KEYDOWN and event.key == pg.K_ESCAPE". This allows the window to close whenever the event triggers. For line 162, once the for loop ends (the video ends), the window closes instead of crashing.

• I have provided code that clearly demonstrates the bug and that only works correctly when applying this fix
• I have added suitable tests demonstrating a fixed bug or new/changed feature to the test suite in tests/
• I have properly documented new or changed features in the documentation or in the docstrings
• I have properly explained unusual or unexpected code in the comments around it

[coveralls]

Coverage decreased (-0.04%) to 68.4% when pulling 3667459 on jlindo33:master into 778233d on Zulko:master.

[mondeja]

Thank you for opening this pull request @Victrollia

I'm really worried about if this could have side effects, for example: have you tried this change concatenating multiples previews in the same Python session? Something like:

from moviepy.editor import VideoFileClip

filename = r"media\chaplin.mp4"
clip1 = VideoFileClip(filename)
clip2 = VideoFileClip(filename)

clip1.preview()
clip2.preview()

Also, I've tried to reproduce the problem and I couldn't in the next environment:

• Windows: 10 version 1909
• Moviepy: master branch
• pygame: 2.0.1

Could you specify what are the versions of Windows, moviepy and pygame for which this problem happens? This only happens when running the preview in a Jupyter Notebook, or also appears standalone?

[Victrollia]

Thank you for opening this pull request @Victrollia

I'm really worried about if this could have side effects, for example: have you tried this change concatenating multiples previews in the same Python session? Something like:

from moviepy.editor import VideoFileClip

filename = r"media\chaplin.mp4"
clip1 = VideoFileClip(filename)
clip2 = VideoFileClip(filename)

clip1.preview()
clip2.preview()

Also, I've tried to reproduce the problem and I couldn't in the next environment:

• Windows: 10 version 1909
• Moviepy: master branch
• pygame: 2.0.1

Could you specify what are the versions of Windows, moviepy and pygame for which this problem happens? This only happens when running the preview in a Jupyter Notebook, or also appears standalone?

Tested on Jupyter Notebook, on Windows 10 10.0.19041 Build 19041. Tested with two previews like in the sample code you provided, once one closes, the next clip preview opens. Didn't add a checkmark on tests because it was mentioned prior that it is tricky to test pygame. Only two lines were added to close the pygame to minimize the chances of any side effects. The first one closes the window if it was interrupted midway while the clip was playing, but then I noticed that it would still crash if the preview ended, that's why another line of code was added that closes the window once it ended the preview. Contributing to this project has been an assignment for a capstone class for CS degree, and therefore my team (3 other people) had the same issue with crashing previews on their Jupyter Notebooks. The Moviepy master branch was cloned recently so it's the latest version. Tested on Python 3.8 & 3.9. Using the latest version of pygame (2.0.1). Let me know if you have any other questions.

[mondeja]

Thanks for the detailed response @Victrollia 🙏

I finally have been able to reproduce it. Seems that your fix has no side effects in any platform and solves the problem, it's perfect 👍

[mondeja]

Thanks again for the fix! If you or someone from your team finds another problem, do not hesitate to open a pull request 💯