[HarfBuzz] hb_ot_tag_to_language

[Richard Wordingham]

On Mon, 10 Mar 2014 09:04:06 +0700
James Clark <jjc at jclark.com> wrote:

> This
> makes me wonder whether it would be better/more robust to map an IETF
> language tag to an ordered list of OT langsys tags, and then HB would
> use the first langsys tag that the font supports. However, I am not
> sure it is worth the effort/complication, since most of these cases
> are pretty obscure, and it's easy and efficient for fonts to make
> multiple langsys tags behave the same.

So what happens when a tag is assigned to a language?  Should the
assignment of a tag for Northeastern Thai suddenly result in NE Thai
text in the Tai Tham script being rendered in a Northern Thai style
rather than a Lao style, just because a Tai Tham font caters for
Northern Thai (NTA) as default but has Lao (LAO) features for when the
text is tagged as Lao?

I appreciate it could get silly - I believe NE Thai should render Latin
script e-mail addresses using the same typography as is normally used
in Thai, rather than following any Lao habits, which would be more
likely to be based on French habits.

Richard.