[csswg-drafts] [css-inline-3] About the central baseline (#5177)

fantasai has just created a new issue for https://github.com/w3c/csswg-drafts:

== [css-inline-3] About the central baseline ==
[XSL:FO](https://www.w3.org/TR/xsl/#area-alignment), [css-inline-3 2002 WD](https://www.w3.org/TR/2002/WD-css3-linebox-20020515/#AlignmentBaselineType), and [SVG1.1](https://www.w3.org/TR/SVG11/text.html#BaselineAlignmentProperties) define the `central` baseline in terms of the ascent / descent metrics. However, we know that these metrics are [not interoperable](https://github.com/w3c/csswg-drafts/issues/2228). We could define it as the same mysterious metric used for `vertical-align: text-top` and `vertical-align: text-bottom` (which is how I've currently drafted the definition), but to the extent that ends up being equivalent to this non-interoperable ascent/descent metrics (does it?), we have the same problem...

The `central` baseline is defined as the default for vertical text layout. And that default really needs to be something interoperable. So I see two ways forward here:

- Option A: Define `central` in a way that everyone can implement.
- Option B: Add an `ideographic-central` baseline halfway between the `ideo` and `idtp` baselines, which falls back to the ambiguously-defined `central` baseline when those metrics are missing, and make *that* the default in vertical writing modes.

Interested to hear from @litherum, @jfkthame, @kojiishi, @macnmm ...

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/5177 using your GitHub account

Received on Saturday, 6 June 2020 06:40:44 UTC