FIX: AnnotationBbox extents before draw

[rcomer]

PR summary

Fixes #24453

Calling update_positions before working out the bbox within get_tightbbox means constrained layout will get sensible numbers to work with so the example from the issue works as expected. We can now also have constrained layout make space for the annotation if it is not contained within the axes:

import matplotlib.pyplot as plt
from matplotlib.offsetbox import AnnotationBbox, TextArea

fig, ax = plt.subplots(layout="constrained")

ab = AnnotationBbox(
    TextArea("Some text", textprops={"size": 42}),
    (1, 0.5),
    xycoords="axes fraction",
    box_alignment=(0.5, 0.5),
    pad=0
)

ax.add_artist(ab)
fig.savefig("annotation_box.png", dpi=100)

I'm not sure where get_window_extent is used, but I updated that in the same way for consistency (and to get the test passing after I removed the draw from it).

Also split the test into two so that the two methods can be checked independently of each other.

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
• [N/A] New Features and API Changes are noted with a directive and release note
• [N/A] Documentation complies with general and docstring guidelines

[oscargus]

Minor suggestion, but otherwise looks good!

[rcomer]

I don't know what's going on with the Azure Linux tasks. If I click through to Azure it says they all succeeded. But they are currently showing for me as in progress below.

[tacaswell]

This seems correct to me, but I am a bit concerned about how to drive these objects to a state where they do not know what Figure they are part of.

I'm confused

[tacaswell]

Sorry, hid my comment was working on the wrong branch 🤦🏻

[rcomer]

@tacaswell has pointed out that if you take the code from the OP and use plt.show(), then resize the window, the result jumps around. I welcome any guidance/suggestions about where to look to understand that.

[QuLogic]

I can't reproduce that, and also @tacaswell mentioned that he was on the wrong branch?

[rcomer]

@tacaswell mentioned at the start of yesterday's call that he then tried with the right branch and it was still a problem (and I also reproduced it after the call). I have also now reproduced with multiple calls to savefig and set_size_inches. Everything seems fine if you don't resize.

import matplotlib.pyplot as plt
from matplotlib.offsetbox import AnnotationBbox, TextArea

fig, ax = plt.subplots(layout="constrained")
fig.set_facecolor('lightgray')

ab = AnnotationBbox(
    TextArea("Some text", textprops={"size": 42}),
    (1, 0.5),
    xycoords="axes fraction",
    box_alignment=(0.5, 0.5),
    pad=0
)

ax.add_artist(ab)

plt.savefig("test1.png")
fig.set_size_inches(8, 3)
plt.savefig("test2.png")
plt.savefig("test3.png")

I'm using QtAgg.

Edit: if I run this with main, the second and third images are the same as with my branch...

As there are issues I'm dismissing the review for now.

[QuLogic]

Oh, I see it's because it's at (1, 0.5), not (0.5, 0.5) as in the original issue. I thought that's where you meant by OP and not from here.

[rcomer]

Ok I think I have it. I probably need to go educate myself better about what stale actually means....

@tomicapretto I think this also now fixes the case from tomicapretto/flexitext#11 (comment)

[rcomer]

Should I add a test for the draw-then-resize case? I'm not sure how realistic it is that a future contributor would break it in that specific way.

[tacaswell]

I think this is fine without an additional test.