[HarfBuzz] Handling OpenType layout across itemisation boundaries

[Jonathan Kew]

On 9/11/15 18:31, Khaled Hosny wrote:
> While reading page 13 of John Hudson’s IUC39 presentation [1], I was
> wondering if HarfBuzz can handle script, language and direction
> properties the same way it handles optional features; i.e. instead of
> sending HarfBuzz buffers that has a single script, language and
> direction, one sends a single buffer for the whole paragraph with
> arrays of script etc. ranges similar to hb_feature_t ranges and let
> HarfBuzz do its magic on it, allowing for any cross boundary lookups to
> be applied as the required context will not be lost.
>
> WDYT?
>
> 1. http://tiro.com/John/Hudson_IUC39_Beyond_Shaping.pdf
> _______________________________________________

While this might be nice in principle, I suspect it would be of limited 
value in most real-world use cases, because it's very common that 
script- and language-run boundaries also turn out to be font boundaries. 
(This is much less likely to be the case for language changes within a 
single script, of course; but it's also relatively uncommon for content 
to actually be marked-up for language at this level.)

So I'm not sure it'd be worth the added complexity for the few cases 
where it could actually be applied.

JK