I see - thank you very much for the explanation and test cases! Sounds good to me. :)
☆*PhistucK* On Mon, Oct 20, 2025 at 8:15 AM Frédéric Wang <[email protected]> wrote: > Hi, > Le 18/10/2025 à 19:51, PhistucK a écrit : > > Hmmm how does it know whether to mirror or not to mirror? And what will be > mirrored? > Is there an example/demo of failure, success and fix-dependent success > renderings? > > First note that right-to-left layout of MathML formulas as well as text > mirroring inside MathML formulas is already supported. For example Chromium > lays out the following formula from right-to-left and mirrors summation, > "element of" and right/left fences (but not the rest of the text): > > <!DOCTYPE html> > <meta charset="utf-8"/> > <link rel="stylesheet" href= > "https://fred-wang.github.io/MathFonts/XITS/mathfonts.css"; > <https://fred-wang.github.io/MathFonts/XITS/mathfonts.css>> > <math dir="rtl" display="block"> > <mrow> > <munderover> > <mo largeop="false">∑</mo> > <mrow> > <mi>n</mi> > <mo>=</mo> > <mn>1</mn> > </mrow> > <mn>∞</mn> > </munderover> > <mfrac> > <mn>1</mn> > <msup> > <mi>n</mi> > <mn>2</mn> > </msup> > </mfrac> > </mrow> > <mo>∊</mo> > <mrow> > <mo stretchy="false">(</mo> > <mfrac> > <mn>3</mn> > <mn>2</mn> > </mfrac> > <mo>,</mo> > <mfrac> > <mn>7</mn> > <mn>4</mn> > </mfrac> > <mo stretchy="false">]</mo> > </mrow> > </math> > > Attached file rtl-math.html uses largeop="true" and stretchy="true" > instead: the summation symbol is drawn bigger, the fences are stretched > vertically but mirroring no longer happens (see attached screenshot > rtl-math-chrome-canary-experimental-web-platform-features-disabled.png). > This intent is trying to fix the latter while still preserving the > largeop/stretchy feature (see > rtl-math-chrome-canary-experimental-web-platform-features-enabled.png for > how it should look like). I believe that gives you an example of failure, > success and fix-dependent success renderings. > > As I said, right-to-left layout of formulas is described in the MathML > Core spec, covered by tests and already implemented in Chromium. Regarding > mirroring technique of text (character-level and glyph-level mirroring) > they are described outside MathML Core, and that spec was amended to use > these techniques for largeop/stretchy operators. You can find demos and > more details on the explainer: > https://people.igalia.com/fwang/mathml-operator-mirroring-explainer.html > > Does the dir="rtl" attribute have to be specified specifically on <math>, > or will it inherit the directionality of the ancestor? > Hebrew, as far as I am aware, uses left-to-right for written math, so > inheriting regardless of the language would not be correct for Hebrew, I > think? > > You are right regarding Hebrew. Actually even in some Arabic countries > text is written from right-to-left but mathematical formulas remain in > left-to-right direction. That's why the default UA sheet for MathML sets > "direction: ltr" on the <math> element: > https://w3c.github.io/mathml-core/#user-agent-stylesheet ; so indeed it's > necessary to use an explicit dir="rtl" (which is mapped to direction: rtl). > > Hope that answers your questions, > > Frédéric > > > ☆*PhistucK* > > > On Tue, Oct 14, 2025 at 2:53 PM Chromestatus < > [email protected]> wrote: > >> *Contact emails* >> [email protected], [email protected] >> >> *Specification* >> https://w3c.github.io/mathml-core/#layout-of-operators >> >> *Summary* >> Support for character-level and glyph-level mirroring when rendering >> MathML operators in right-to-left mode. When using RTL mode some operators >> can be mirrored by changing them to another code point (e.g. a right >> parentheses becomes a left parentheses). This is character-level mirroring, >> with equivalences defined by Unicode's `Bidi_Mirrored` property. There are >> operators that have no appropriate mirroring character. Glyph-level >> mirroring applies in this case, with the `rtlm` font feature, where another >> glyph can replace it in a mirrored context. Some existing implementations >> mirror the original glyph directly, but this may change the meaning for >> asymmetrical characters, such as the clockwise contour integral. >> >> *Blink component* >> Blink>MathML >> <https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3EMathML%22> >> >> *Web Feature ID* >> mathml <https://webstatus.dev/features/mathml> >> >> *TAG review* >> None >> >> *TAG review status* >> Not applicable >> >> *Risks* >> >> >> *Interoperability and Compatibility* >> None >> >> *Gecko*: Shipped/Shipping ( >> https://bugzilla.mozilla.org/show_bug.cgi?id=945183) Working >> implementation shipping under the `mathml.rtl_operator_mirroring.enabled` >> feature. Planning to send an intent to ship. >> >> *WebKit*: In development Already has character-level mirroring. rtlm >> support is being worked on for the harfbuzz ports. >> >> *Web developers*: No signals >> >> *Other signals*: >> >> *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? >> None >> >> >> *Goals for experimentation* >> >> >> *Ongoing technical constraints* >> None >> >> *Debuggability* >> None >> >> *Will this feature be supported on all six Blink platforms (Windows, Mac, >> Linux, ChromeOS, Android, and Android WebView)?* >> Yes >> >> *Is this feature fully tested by web-platform-tests >> <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>?* >> Yes >> New tests: - Character-level mirroring: checks that when switching text >> direction the codepoints of the characters change to the corresponding >> BidiMirrored equivalent (e.g. right to left parentheses) - Glyph-level >> mirroring: checks that the rtlm font feature is supported and that a >> specific glyph is used for certain characters when switching text direction. >> >> *Flag name on about://flags* >> None >> >> *Finch feature name* >> MathMLOperatorRTLMirroring >> >> *Requires code in //chrome?* >> False >> >> *Tracking bug* >> https://issues.chromium.org/issues/40120782 >> >> *Estimated milestones* >> DevTrial on desktop 140 >> DevTrial on Android 140 >> >> *Link to entry on the Chrome Platform Status* >> https://chromestatus.com/feature/6317308531965952 >> >> *Links to previous Intent discussions* >> Intent to Prototype: >> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/686d2758.170a0220.a35ba.00d7.GAE%40google.com >> >> >> This intent message was generated by Chrome Platform Status >> <https://chromestatus.com>. >> -- >> You received this message because you are subscribed to the Google Groups >> "blink-dev" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To view this discussion visit >> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/68ee55b8.050a0220.2a8282.0245.GAE%40google.com >> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/68ee55b8.050a0220.2a8282.0245.GAE%40google.com?utm_medium=email&utm_source=footer> >> . >> > -- > You received this message because you are subscribed to the Google Groups > "blink-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion visit > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CABc02_JdGb5qv3A3JEs0SCbkK7NtJ3F74HN1EeyODbavy9YkcQ%40mail.gmail.com > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CABc02_JdGb5qv3A3JEs0SCbkK7NtJ3F74HN1EeyODbavy9YkcQ%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > > -- > You received this message because you are subscribed to the Google Groups > "blink-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion visit > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/fe9dd258-93dc-4104-baca-5cee655f393e%40igalia.com > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/fe9dd258-93dc-4104-baca-5cee655f393e%40igalia.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "blink-dev" group. 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