Exciting times! Since the layout implementation of MathML is pure NG (i.e. it has no legacy engine counterpart), you should be aware that this is somewhat uncharted territory. We *do* have mechanisms that kick in when we need to fall back to legacy layout (e.g. when printing, or when there are tables inside multicol), and have NG-only content inside (such as MathML), but no pure NG features have shipped yet, so we don't really know how well this works on the world wild web.
That said, we're also about to ship container queries, which has the same problem - so you're not alone. I was hoping that we'd be rid of the legacy engine completely before we started shipping pure NG features, because of this risk. I'm not saying that we definitely need to wait for the legacy engine to be completely gone, but you need to be aware of the risk, at least. Maybe clusterfuzz will find something interesting once this feature is switched to "stable". :) By the way, I just tested, and MathML inside legacy layout doesn't seem to work. I filed https://bugs.chromium.org/p/chromium/issues/detail?id=1338882 Frédéric Wang <fw...@igalia.com> writes: > Contact emails > > fw...@chromium.org, rb...@chromium.org, bkard...@igalia.com > > Explainer > > https://github.com/mathml-refresh/mathml-core/blob/master/docs/explainer.md > https://people.igalia.com/fwang/explainer-font-family-math > > Specification > > https://mathml-refresh.github.io/mathml-core > > Design docs > > https://drafts.csswg.org/css-fonts-4/#valdef-font-family-math > https://w3c.github.io/mathml-aam > https://docs.google.com/document/d/1biGEaWN8ThNTDtAbT1M5GIf6N5uQLWdxh2QhrG9uN5c > > https://docs.google.com/document/d/1bvY_Npe2zLW_705KXdmecsH6P9I9wBMpHRsZ9CxWNOI/edit#heading=h.u9hwm9tp8nuy > > > Summary > > Adds native DOM/IDL, accessibility support and CSS-compatible OpenType-based > layout of mathematical formulas. The reference > specifications are MathML Core (which describes in extensive details a > fundamental subset of the MathML 3 recommendation), MathML AAM > (which describes mapping to platform accessibility APIs). This includes the > "math" font-family as well as features included in section "CSS > Extensions for Math Layout". > > Blink component > > Blink > > Search tags > > mathml > > TAG review > > https://github.com/w3ctag/design-reviews/issues/438 > https://github.com/w3ctag/design-reviews/issues/313#issuecomment-460523527 > > TAG review status > > Issues addressed > > Risks > > Interoperability and Compatibility > > - This is not implementing the complete list of MathML3, OpenType MATH or > accessibility features that one can find in other browsers. > > - New enhancements (e.g. clarification regarding CSS interoperability) may > not be implemented in other browsers yet. > > - MathML Core and MathML AAM are still working drafts. > > Gecko: Shipped/Shipping > > WebKit: Shipped/Shipping > > Web developers: Positive > (https://twitter.com/search?q=mathml%20chrome&f=live) Users have recently > been excited about it, > experimented exiting implementation under a flag and are eager to see it > shipped soon. It is currently the 5th most starred Blink issue, see > https://bugs.chromium.org/p/chromium/issues/list?can=2&q=component:Blink&sort=-stars&colspec=ID%20Stars%20Pri%20Status%20Component%20Opened%20Summary > > > Other signals: > > Ergonomics > > In the past, MathML trees were not treated specially at all and this was fast > ! Now, more work is needed for pages that do math rendering > e.g. accessing data from the MATH table, handling operator dictionary, using > ink text bounds, performing low-level shaping of stretchy > operators, loading and applying CSS UA sheet, or exposing an accessibility > tree. However, the only performance report we received so far > was issue #1073760, which was discarded after further analysis. In any case, > performance is definitely better than existing non-native > technologies. Additionally, pages will likely need loading WOFF fonts on > operating systems that don't ship math fonts. Work is in progress > here, see https://frederic-wang.fr/update-on-open-type-math-fonts.html for > recent status. > > Activation > > - Editing MathML source is difficult but special authoring tools & converters > do exist. > > - Implementation may not be as complete as expected by users but the spec > tries to allow extensibility and the Math WG provides polyfills > at https://github.com/mathml-refresh/mathml-polyfills > > - Users may require WOFF fonts to properly render formulas (see above). > > Security > > There is a risk due to the new attack surface: > > - Relatively large amount of new code. > > - Newly exposed APIs. > > - Interacting with several parts of the web platform. > > However, risks related to violation of layout algorithm are reduced now that > the specification clarifies how to perform it in a CSS-compatible > way. We've fixed 17 issues reported during 2.5 years of development and there > are currently 0 open security issues (last report was in > March). > > Finally, similar security & privacy considerations as existing layout > specifications apply, see the relevant sections from the MathML Core > spec: https://w3c.github.io/mathml-core/#security-considerations > https://w3c.github.io/mathml-core/#privacy-considerations > > WebView application risks > > Does this intent deprecate or change behavior of existing APIs, such that it > has potentially high risk for Android WebView-based > applications? > > No. > > Debuggability > > - Nothing particular expected besides what is already provided for SVG and > HTML. > > - Existing devtools API was extended to handle "font-family: math", see > https://chromedevtools.github.io/devtools-protocol/tot/Page/#method-setFontFamilies > > Will this feature be supported on all six Blink platforms (Windows, Mac, > Linux, Chrome OS, Android, and Android WebView)? > > Yes > > Is this feature fully tested by web-platform-tests? > > Yes > > Flag name > > MathMLCore > > Requires code in //chrome? > > True (this is only to implement support for “font-family: math”, which has a > user preference menu for math font, see > https://docs.google.com/document/d/1bvY_Npe2zLW_705KXdmecsH6P9I9wBMpHRsZ9CxWNOI/edit#heading=h.u9hwm9tp8nuy). > > Tracking bug > > http://crbug.com/6606 > > Sample links > > https://people.igalia.com/fwang/2022-06-igalia-week-shipping-mathml-in-chromium/#/12 > > https://fred-wang.github.io/MathFonts > > Estimated milestones > > DevTrial on desktop 103 > > DevTrial on Android 103 > > Anticipated spec changes > > Open questions about a feature may be a source of future web compat or > interop issues. Please list open issues (e.g. links to known github > issues in the project for the feature specification) whose resolution may > introduce web compat/interop risk (e.g., changing to naming or > structure of the API in a non-backward-compatible way). > > https://github.com/w3c/csswg-drafts/issues/5866 > https://github.com/w3c/mathml-core/issues/74 > https://github.com/w3c/mathml-core/issues/75 > https://github.com/w3c/mathml-core/issues/76 > https://github.com/w3c/mathml-core/issues/77 > > Link to entry on the Chrome Platform Status > > https://chromestatus.com/feature/5240822173794304 > > Links to previous Intent discussions > > Intent to prototype: > https://groups.google.com/a/chromium.org/g/blink-dev/c/OOZIrtSPLeM > > This intent message was generated by Chrome Platform Status. > -- > Frédéric Wang -- Morten Stenshorne, Software developer, Blink/Layout, Google, Oslo, Norway -- You received this message because you are subscribed to the Google Groups "blink-dev" group. 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