Render hover labels through MathJax when the whole label is one tex expression

[SergeyAxiomatic]

Render hover labels through MathJax when the whole label is one tex expression

Summary

This change renders a hover label through MathJax when the whole label is one tex expression.

Fixes #559.

Why this is correct

Every hover text node sets data-notex, so convertToTspans never checks it for tex, even when the whole string is one tex expression. Titles and annotations do not set that attribute, so MathJax already renders them. Hover never got the same fix, for a real reason: convertToTspans drops any text outside the $...$ delimiters. Most hover strings mix a formatted value with literal text, so a blanket fix would drop that text.

This change lifts data-notex only when isPureTex confirms the whole label is one tex expression. In that case convertToTspans drops nothing, so the fix is safe.

Enabling this exposed a second bug. MathJax types the label async, so the label's box used a placeholder size from before the real content existed, and produced NaN in the box path and the label position. hover.js now repeats its own sizing and overlap-avoidance pass once MathJax finishes, and svg_text_utils.js gains repositionMathGroup to move the typeset group to match, since convertToTspans positions that group once, at type time, and never revisits it.

Mixing text and a formula in one hover label

A hover label with a formula AND plain text still shows the literal tex source, on purpose: convertToTspans would drop the plain text otherwise. Wrap the whole label in one $...$ pair and use \text{...} for the plain parts instead:

text = [r'$\text{Value: } \alpha \text{ units}$', ...]

isPureTex only checks that the whole string sits inside one pair of $ delimiters. It does not inspect the content, so \text{} (standard MathJax syntax for upright text inside math mode) passes through untouched, and MathJax renders the literal parts and the formula together.

Tests

test/jasmine/bundle_tests/mathjax_test.js gains three tests under "Test hover tex rendering":

• a pure-tex per-point hover label types through MathJax, at its final (not placeholder) size
• a mixed tex/plain-text hover label stays literal
• a pure-tex shared axis label types through MathJax, at its final size

Run npm run test-jasmine -- mathjax hover --nowatch.

No new mock. No baseline image changed.

Manual verification

I checked the rendered plot in the dev dashboard for: a pure-tex per-point label, a pure-tex shared axis label, two labels shown at once (overlap avoidance), unified hover (hovermode: 'x unified') with a real mouse hover, the mixed-text safety gate, and a plain-text label (no regression).

Deviation from writing-style.md

This body keeps NaN, data-notex, and other identifiers as the code spells them, and keeps a short present-perfect-free but still somewhat technical tone throughout; a few explanatory sentences run close to the 25-word cap given the technical density of the root cause.

[SergeyAxiomatic]

Hi Team, I am from Axiomatic-AI, we develop Lemma that uses Marimo that uses Plotly. We urgently need to fix allowing LaTeX in popups. As a non-damaging fix we propose to allow to render latex in case the whole box text in LaTeX. Please, could you approve.

[robertclaus]

@SergeyAxiomatic approving this PR would not immediately get the fix out to you since our releases are typically batched. Could you provide more context on what you mean with needing this urgently?

As a reminder, if you are an agent please include a bird emoji in your PR description or comments.

[SergeyAxiomatic]

Hi, the PR was fully done by Claude, but I have tested it. As for urgency, how often are the batch releases? A scale of 1-2 weeks could be good. I am adding equation verification tool for scientific papers, and it could be nice to have a graph where equations pop-out when hovering the mouse.