[MathML4] thin, medium and thick values for mfrac@linethickness

Frédéric Wang <[email protected]> Mon, 1 Aug 2016 18:02:13 +0200
Newsgroups	gmane.comp.web.mathematics
Message-ID	<[email protected]>
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Hi,

The mfrac elements has values "thin", "medium" and "thick" which are
"left up to the rendering agent". This is prone to inconsistencies
between implementations. During Igalia's MathML refactoring, we aligned
WebKit on Gecko's behavior. This is essentially what is suggested in the
MathML in HTML5 implementation note and that should probably be included
in an official MathML recommendation too:

* The default linethickness "medium" is given by the
FractionRuleThickness constant of the MATH table of the font used for
the MathML rendering (see
https://lists.w3.org/Archives/Public/www-math/2016Jul/0025.html for
discussion about how to determine that font).

* "thin" is 50% and "thick" is 200% of the default linethickness (these
values are arbitrary and based on how it has been implemented in Gecko
probably for more than 15 years).

But are these keywords really used in practice? If not maybe you may be
inclined to deprecate them too.

Frédéric


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    <p>Hi,</p>
    <p>The mfrac elements has values "thin", "medium" and "thick" which
      are "left up to the rendering agent". This is prone to
      inconsistencies between implementations. During Igalia's MathML
      refactoring, we aligned WebKit on Gecko's behavior. This is
      essentially what is suggested in the MathML in HTML5
      implementation note and that should probably be included in an
      official MathML recommendation too:</p>
    <p>* The default linethickness <span class="ltx_text MATH
        ltx_font_typewriter">"medium" is </span>given by the <span
        class="ltx_text MATH ltx_font_typewriter">FractionRuleThickness
        constant of the MATH table of the font used for the MathML
        rendering (see
        <a class="moz-txt-link-freetext" href="https://lists.w3.org/Archives/Public/www-math/2016Jul/0025.html">https://lists.w3.org/Archives/Public/www-math/2016Jul/0025.html</a>
        for discussion about how to determine that font).</span></p>
    <p><span class="ltx_text MATH ltx_font_typewriter">* </span><span
        class="ltx_text MATH ltx_font_typewriter">"thin" is 50% and
        "thick" is 200% of the default linethickness (these values are
        arbitrary and based on how it has been implemented in Gecko
        probably for more than 15 years).</span></p>
    <p><span class="ltx_text MATH ltx_font_typewriter">But are these
        keywords really used in practice? If not maybe you may be
        inclined to deprecate them too.</span><span class="ltx_text MATH
        ltx_font_typewriter"></span></p>
    <p><span class="ltx_text MATH ltx_font_typewriter">Frédéric</span></p>
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