On 26/08/2013 2:52 AM, "Tab Atkins Jr." <jackalmage@gmail.com> wrote:
>
>
> The use-case for <auto> has been explained - it provides a useful
> number without the author having to take the time to measure things
> themselves, and there's a good chance that it matches the font
> currently being used, since most pages just uses the browser default
> fonts for most text. The default font for the browser is presumably
> nicely legible, such that matching its x-height is acceptable. Having
> all of your fonts match *some* reasonable x-height is useful all by
> itself; you don't need the ability to specify a specific x-height to
> make this functionality useful.
>
There are quite a few assumptions here that don't hold water.
1. That default font for a browser is nicely legible.
Considering not all browsers allow you you to set defaults for all scripts
... it is pot luck what font you will get and whether it is appropriate for
body text.
2. It assumes that the default fonts have suitable x-heights in the first
place. I can think of some default OS fonts for some scripts that were
optimised for UI and have very small x-heights, which woild provide very
unprefictable results across platforms.
If there is marked difference between x-heights in default fonts across
platforms then auto vlaue woild introduced marked differences in layout for
same content on different platforms.
Khmer on certain platforms is noteable in this regard.
3. That x-height is universal, and whether it will achieve the desired
results, esp in mixed language content.
At the moment we are working on an audit of all Myanmar script Unicode
fonts from point of view of x-height.
Initially taking into account English content, but also eventually taking
into account Thai, Kayah Li and Leke within the mix.
Andrew.