Re: Behaviour for letter-spacing in indic scripts

On 25/04/14 9:32 AM, Richard Ishida wrote:

> If a conjunct doesn't display the virama, it's components and associated
> vowel-signs, diacritics, etc should be kept as a single unit, but
> otherwise the top bar is broken around each akshara.  For example, one
> would expect to see अंतर्राष्ट्रीयकरण [1] stretched as
>
> अं त र्रा ष्ट्री य क र ण
>
> If, however, the virama is displayed explicitly, one would expect to see
> the same word stretched as
>
> अं त र् रा ष् ट् री य क र ण

Unless an explicit virama has been triggered by insertion of ZWNJ (see 
TUS fig9.3), I don't see any 100% reliable way to determine whether a 
particular conjunct in a particular font displays with an explicit 
virama or not. For an OpenType font using <dev2> shaping, it might be 
possible to get an indication from querying the glyph string after GSUB 
cluster shaping features have been applied -- presuming that the font 
lookups have been made in a predictable way -- looking for glyphs that 
map to the virama character. But for the older <deva> shaping it is 
common for fonts to contain nominal half form glyphs (accessed via the 
<half> feature) that include a visible virama (below retroflex letters 
such as ट). In that case you have a visibly explicit virama but nothing 
in the glyph string to indicate that it is there. Nor can you make an 
assumption that a specific subset of letters will be handled in this 
way, because छ may display with explicit virama or with a true half form 
depending on the individual typeface design.

JH

Received on Friday, 11 July 2014 19:53:03 UTC