[webkit-dev] Implementing MathML stylistic attributes in WebKit

[Frédéric Wang]

On 02/09/2019 16:11, Frédéric Wang wrote:
> Hello,
>
> Currently MathML attributes mathvariant, displaystyle and scriptlevel
> [1] [2] are implemented in WebKit using custom "style resolution" and
> "one-glyph rendering" inside the MathML layout code [3] [4] [5]. These
> features involve text rendering and interaction with CSS font-size, so
> it is difficult to implement them properly and completely that way.
> There are known bugs and missing features right now (e.g. mathvariant
> transform only applies to one-character strings, automatic
> displaystyle/scriptlevel does not work with fractions, etc)

Hi,

An update on this, we have been discussing these and new properties with
the CSSWG:

https://github.com/w3c/csswg-drafts/issues/5384

The math-depth / math-style CSS properties are being implemented in
Chromium and renamed/exposed/tweaked in Gecko:

https://mathml-refresh.github.io/mathml-core/#the-math-style-property

https://mathml-refresh.github.io/mathml-core/#the-math-script-level-property

So it makes sense to implement them in WebKit (it seems we still don't
have a "intent to" mechanism, but people can follow
https://bugs.webkit.org/show_bug.cgi?id=195797).

The CSSWG is fine with a new text-transform value for automatic italic
but using it for other values is controversial (see
https://github.com/w3c/csswg-drafts/issues/3775). So if we want to
preserve backward compatibility and fix existing bugs with mathvariant,
we should probably re-implement it using an internal math-transform
property (like what Gecko does) which according to our previous
discussion is nowadays possible in WebKit.

-- 
Frédéric Wang

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.webkit.org/pipermail/webkit-dev/attachments/20200925/1dc21935/attachment.htm>