Artist autolim

[jayyxiao]

PR summary

Move auto-limit logic inside respective Artists

This will allow for relim to work with Collections. closes #25139 .

_update_*_limits() were moved inside respective Artists. An _in_autoscale flag was created in base Artist, with setters and getters. This flag can be a bool or tuple, as specified in #15595 . Also, _update_limits() was created in Collection. Thus, relim checks the _in_autoscale flag and calls a generic _update_limits(), which now exists in Collection.

_in_autoscale is set to True in the Artist constructor. Expansion to a tuple will be done by the setter. _in_autoscale can be set to False when theautolim parameter of add_collection is False.

Since I am a new contributor, I hope this can be a starting point. I'm just looking for some feedback.

PR checklist

• "closes #0000" is in the body of the PR description to link the related issue
• new and changed code is tested
• [N/A] Plotting related features are demonstrated in an example
• New Features and API Changes are noted with a directive and release note
• Documentation complies with general and docstring guidelines

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[tacaswell]

@jayyxiao I'm sorry this got no attention when you opened this (I have been super busy the last month and know some of the other core developers are in a similar situation). I assure you our lack of response is in no way commentary on your work!

Giving it a quick skim this seems like it is heading the right direction, however I have one concern. Passing the Axes object into an artist method which then "returns" the results by mutating its parent is a bit odd. I think it would be better if the return from _update_limits was made uniform so the loop over children would look something like:

for artist in self.children:
    if not visible_only or (artist.get_visible() and artist.get_in_autoscale()):
        limits, to_update = artist._get_limits(self.transData)
        self.update_datalim(limits, **to_update)

Put another way, currently we have too much artist-specific stuff in Axes, but this swings too far the other way and puts too much Axes specific stuff into the Artists.

Additionally, being able to get the data limits of an artist is useful for other things (maybe cheaper hit-checking for picker, improving the auto-placement of the legend, etc) so being able to get at this might be useful.