initialize zoom center even when viewer not shown

[kecnry]

Description

This pull request sets the zoom center/radius traitlets as soon as the viewer is assigned back to the state to ensure they are initialized immediately rather than waiting for a zoom event when the viewer is shown on the screen. @duytnguyendtn - can you confirm if this fixes the case that you were running into?

Fixes #3217

Change log entry

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.56%. Comparing base (7b8aeba) to head (b6de9b5).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3222   +/-   ##
=======================================
  Coverage   88.56%   88.56%           
=======================================
  Files         125      125           
  Lines       18751    18754    +3     
=======================================
+ Hits        16606    16609    +3     
  Misses       2145     2145           

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[pllim]

Thanks! Maybe turn Duy's example code into a regression test? 🤔

[kecnry]

yep - wanted to make sure this works on top of #2872 first and see whether tests there will cover this case or whether we want a dedicated test just for this

[kecnry]

on second thought, this can be tested on an even simpler case (confirmed to fail on main). @duytnguyendtn - if you think this will later get duplicated coverage in #2872, feel free to remove the test there when you rebase.

[pllim]

Can we be a little more specific? Maybe allclose check instead of just non-zero check?

[kecnry]

I intentionally left this flexible so if the zoom behavior changes this does not break except for the regression (where the values were left uninitialized at their default values). Other tests handle specific zoom-tool behavior already. But if you'd still prefer to enforce the current values, I can easily make that change.

[duytnguyendtn]

Thanks for the quick fix! I tested this on top of #2872 and that fixed one of the two failures that happened, but digging into it last night it seems like the two failures are two separate cases. But at least the one that was failing due to the uninitialized zoom center is now passing. Thanks!

[duytnguyendtn]

on second thought, this can be tested on an even simpler case (confirmed to fail on main). @duytnguyendtn - if you think this will later get duplicated coverage in #2872, feel free to remove the test there when you rebase.

While technically true the test_autocenter_coords does cover this initialization case, I would say it's incidental rather than intended. I could see value in having this test as a standalone to be clear what's failing, in the event something causes this to break. Ultimately I'll leave that to y'all about whether the extra runtime is worth it for testing clarity

[pllim]

Thanks!