Add a preview functionality

[Fifourche]

Following #99 , added functions to enable a preview ability. This preview capability is compatible with the slider as it allows to still change frame interactively using it (see video snippet).

animation_previewer.mp4

I'll add corresponding tests if you agree on the idea at least !

[codecov]

Codecov Report

Attention: Patch coverage is 87.88732% with 43 lines in your changes missing coverage. Please review.

Project coverage is 86.14%. Comparing base (07f93c7) to head (72dc5ae).
Report is 140 commits behind head on main.

Files with missing lines	Patch %	Lines
napari_animation/_qt/frameslider_widget.py	89.18%	24 Missing ⚠️
napari_animation/_qt/playbutton_widget.py	76.78%	13 Missing ⚠️
napari_animation/_qt/_tests/test_play.py	91.54%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #100      +/-   ##
==========================================
+ Coverage   84.91%   86.14%   +1.23%     
==========================================
  Files          21       24       +3     
  Lines         928     1256     +328     
==========================================
+ Hits          788     1082     +294     
- Misses        140      174      +34     

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[sofroniewn]

Hi @Fifourche, sorry just seeing this now. Maybe @alisterburt @tlambert03 and I can give this some review when we get the chance. Am I right in thinking this is sort of like having a "play button" for our preview slider? If so we might be able to re-use some of the play button code we have for our dims slider. I'll check out #99 too when i can as well. Nice work here!!!

[Fifourche]

Hi ! :) Yes that was the idea indeed, but I also wanted to give the ability to have a play function even without the GUI.

That's why I started #99 in fact ! I wanted to have a current_frame attribute much like the dims.current_step, so that I could reuse the dims_slider play function there. In this PR I already use something similar to what's happening in the dims slider play (AnimationWorker, and precautions to allow the slider to still be interactive).

I still need to work on #99 though, and give the current_frame attribute to the FrameSequence rather than Animation for instance.

[sofroniewn]

@Fifourche - do you want to reuse the "play button" from inside napari here

It wasn't quite clear to me how to turn the playing on and off based on the GUI

[Fifourche]

Hey ! Yes, that's I want to do indeed ! But as we didn't have any equivalent of the Dims element, I wanted to wait for #99 to have something similar ; now I want to replace the slider we have for an equivalent of the QtDimSliderWidget from napari, maybe without some options like reverse play. I should probably put this PR as a draft one in fact, sorry ! ^^

[sofroniewn]

I should probably put this PR as a draft one in fact, sorry ! ^^

No worries, all good! Let us know if we can help!!

[Fifourche]

I have a working version of it, ~ready for review I guess ! :)

What I'd like to do still is to move the QtPlayButton from here to superqt, and use subclasses if needed in napari and napari-animation. Do you think this would be worth it @tlambert03 ?

[Fifourche]

The tests failed here but for a napari related issue ?

[sofroniewn]

The tests failed here but for a napari related issue ?

Ok thanks for flagging! @alisterburt or I should be able to review this soon, thanks!!

[Fifourche]

Once again, a napari related issue :

    File "/home/runner/work/napari-animation/napari-animation/.tox/py39-linux-pyside/lib/python3.9/site-packages/napari/_qt/utils.py", line 304, in remove_flash_animation
      widget.setGraphicsEffect(None)
  RuntimeError: Internal C++ object (QtWidgetOverlay) already deleted.

Otherwise it seems ok I think !