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Re: [MathML 4] Add rules to map from non-combining to combining accents

From: Frédéric Wang <fwang@igalia.com>
Date: Fri, 22 Feb 2019 15:05:18 +0100
To: www-math@w3.org
Message-ID: <4a70f04c-729b-99fe-e31c-5616a87a6f25@igalia.com>
Moved to https://github.com/mathml-refresh/mathml/issues/11

On 09/03/2018 18:31, Frédéric Wang wrote:
>
> Hello,
>
> Another idea for a future MathML spec.
>
> MathML suggests to use non-combining characters for operators and most
> of the operators in its dictionary are non-combining. However, TeX
> seems to rely on combining characters for accents and hence in
> practice OpenType fonts with a MATH table only provide size variants
> or glyph assemblies for these combining characters ; and nothing for
> the non-combining equivalents. That means non-combining characters are
> not stretchable with these fonts and users may be tempted to use the
> combining versions instead.
>
> I think it would be good if MathML specifies how web engines can
> fallback from non-combining to combining accents in order to stretch
> accents. Ideally, we should have a list of such mappings (maybe data
> in the XML Entity Definitions for Characters). For example to stretch
> U+00AFMACRON, WebKit will also try and find size variants or glyph
> assemblies associated to that character inthe OpenType MATH table and
> otherwise fallback to data associated to U+0304 (COMBINING MACRON) or
> U+0305 (COMBINING OVERLINE).
>
> Having such a list will allow to improve consistencies between web
> engines and to write WPT tests for that feature (currently it's
> non-standard so only tested in WebKit repo).
>
> WebKit bug: https://bugs.webkit.org/show_bug.cgi?id=159513
>
> Mozilla bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1285277
>
> -- 
> Frédéric Wang - frederic-wang.fr


-- 
Frédéric Wang
Received on Friday, 22 February 2019 14:05:51 UTC

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