Support mathjax (v3) math rendering#98
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Introduces xkcd-mathjax3.js, a self-contained drop-in script that
renders MathJax 3 CHTML through xkcd-script:
- Hand-drawn sqrt surd and fraction-vinculum overlays built at runtime
from font-extracted glyph outlines via a cut-and-extend algorithm
(no manually maintained SVG paths in the script).
- pt8a_mathjax3.py orchestrator extracts the extensible glyph data
from pt7's SFD and splices it into the script between markers.
- ss01 stylistic-alternate wiring for display-sized sigma / pi /
integral: the base font carries inline-sized summation / product /
integral at U+2211 / U+220F / U+222B with unencoded .disp variants
reached via the ss01 feature, so a single xkcd-script.woff serves
both body text and MathJax math (no separate math font).
- Initial samples directory with playwright-driven PNG generator.
Each YAML group may carry a `mathjax: { packages: [...], tags: ... }`
block so each sample loads only the MathJax TeX-input packages it
needs; the default is no extras.
- ss01 GSUB lookup registered under DFLT script so browsers shape the common-script U+2211 / U+220F / U+222B operators through the feature (without DFLT binding, font-feature-settings has no effect on those codepoints and operators render at letter size). - Consolidate inline-sum / inline-int / inline-prod into a single inline-ops multi-formula grid so the three inline operators diff together against the same render context.
MathJax CHTML wraps each char of \text{...} in a width-0 mjx-c with
padding-right baked from MJXTEX metrics, which produced fake-ligature
overlaps and big gaps when xkcd-script's different advances were
applied. Collapse mjx-c / mjx-c::before inside mjx-mtext to
display: inline; padding: 0; width: auto so the text run flows
naturally through HarfBuzz instead.
Three DOM-overlay passes in xkcd-mathjax3.js — replaceStretchyBraces, replaceStretchyParens, replaceStretchyBrackets — replace the MathJax CHTML stacked-piece assemblies (mjx-stretchy-v) and TEX-Sn sized variants with hand-drawn glyphs extended via the cut-and-extend runtime. - braceleft.tall + tall paren imports (pt5), bracket reuses the regular bracketleft glyph for straight strokes. - Paren strokes thin uniformly with thicknessScale (X+Y shrink, then Y restored), compact mode for \binom via mjx-texatom detection. - TEX-S1 filtered out so \bigl[ etc. stay at MathJax's intended size.
replaceCombiningAccents rewrites single-letter \hat / \bar / \tilde / \dot / \ddot / \check / \breve / \acute / \grave mover boxes as a mjx-c-accent text node containing baseChar + combiningChar, so HarfBuzz shapes the pair through xkcd-script's mark anchors instead of falling back to MathJax's CSS-positioned overlay. The injected base character comes from the math-italic codepoint directly — pt6 cmap-aliases math-italic / bold / Greek codepoints to their plain Latin / Greek glyphs, so the browser shapes the text node through the alias automatically (no JS-side codepoint remapping needed). replaceWideMovers handles \vec (font's U+2192 overlay), \overline (emdash extender), \widehat / \widetilde (CSS-centred non-stretchy caret/wave).
- replaceVerticalRules + grouped rule collection draw one continuous hand-drawn bar per shared edge in array / matrix tables, instead of per-cell border segments. Vertical bars are mirrorBarHTML rotated 90° around their top-left corner. - replaceVinculums groups bars by row to avoid stitched-together segments at row boundaries, and honours dataset.xkcdHidden so the sqrt's combined surd+bar overlay does not get a second bar painted on top. - Digit-1 padding: collapse mjx-mn mjx-c padding to 0 / width auto, mirroring the mjx-mtext fix — xkcd-script's narrow `1` no longer leaves a visible gap right of every digit.
arrowright is added as an extensible glyph (EXTENSIBLE_CONFIG entry)
and replaceStretchyArrows overlays stretched copies for:
- \xrightarrow{f} / \xleftarrow{g} with labelled arrows.
- \overrightarrow{ABC} / \overleftarrow{ABC} wide-mover cases (the
single non-stretchy fallback in replaceWideMovers is replaced for
multi-letter bases).
- \vec{multi-letter} where the natural -> would look undersized.
- All four AMScd directions (CD horizontal + vertical arrows).
The amscd-commutative-diagram sample opts into the [tex]/amscd
package via its `mathjax:` block — no other sample loads amscd.
- \circ (U+2218): reuses the ring contours extracted from Å (same hand-drawn shape used as a diacritic above å/ů), recentred on the math axis. - \ast (U+2217): asterisk outlines translated down to the math axis. - \otimes (U+2297): hand-drawn from the 2034 equations comic via extras/2034_equations_2x__circled_times.png. - Use createChar(cp, name) instead of createMappedChar(cp) when adding Unicode-mapped glyphs in pt6 — createMappedChar leaves unicode=-1 in the SFD and the OTF cmap omits the codepoint (which is why \cdot had been silently falling back to MJXTEX since it was introduced). - Samples: align-eqref (AMS align + tag + eqref, opts into the [tex]/ams package via its `mathjax:` block) and math-symbols-zoo (binops / relations / arrows / delimiters / logic / misc reference).
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Closes #90 and #96.
Follows-up from lessons learned in #96 to introduce an
xkcd-script-mathjax3.jsfile that you can include to have XKCD rendering of mathjax (v3). I believe that mathjax v4 gives us more flexibility in terms of custom fonts etc., but for now I targeted v3 as it is still particularly prevalent in the wild. I designed this setup to easily add v4 support independently of the v3 one (and it shouldn't be as much work as was done here).