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

Previous Topic Next Topic
classic Classic list List threaded Threaded
1 message Options
Reply | Threaded
Open this post in threaded view

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

Frédéric Wang-2


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.