[WIP] Explore ways to make napari-animation work with async prototype

This task is motivated by a comment in the NAP’s first PR.

The napari-animation plugin is an example of a plugin that relies on the mutation of Dims.current_step being synchronous (both with an active viewer and headless). There are likely others too, but it should serve as a good example that we know is well used.

Here are some possible solutions/ideas, but others likely exist.

• Define new async entry points in the API and leave the existing sync ones alone (e.g. Dims.set_current_step_async).
• Define a context manager that forces synchronous (or maybe asynchronous?) slicing.
• Define functions like LayerSlicer.waitUntilIdle to wait for any pending slicing tasks to be done.

The output of this task should describe a solution with working prototype code. We should probably cover the examples in the napari-animation repo. We should incorporate the description into the NAP to address the questions and feedback in the original comment and replies.

Edit: Initial text comes from @andy-sweet. Github didn’t seem to track the attribution.

[alisterburt]

loving watching this from afar @kephale and @andy-sweet !

Define a context manager that forces synchronous (or maybe asynchronous?) slicing.

I think I like this option the most 😃

[kephale]

Great. I’m happy to close this one now.