[OpenType] Re: [mpeg-OTspec] Vertical ligatures

[John Hudson]

Eric Muller wrote:

> ... currently the resolution of feature
> tags to actual lookups takes into account an OT script and an OT
> language; it could also include another parameter, the relative
> position. Thus, ('liga', script, language, horizontal_lr) could resolve
> to lookups that forms the usual "fi" ligature for the run<f, i>, while
> ('liga', script, language, horizontal_rl) could resolve to lookups that
> form the "fi" ligature for the run<i, f>....

Boustrophedon here we come! I would very much welcome this capability.


While we're on the subject of relative position and direction, I wonder 
if there is any hope of solving the issue of contextual substitutions in 
which the context string extends across direction run barriers? The case 
I run into is the Arabic year sign, which is an encompassing RTL 
character that is stored before and sits to the right of one or more LTR 
numerals, which are followed in many instances by an RTL isolated mim 
character. In many styles a variant form of mim should be used in this 
situation to avoid colliding with the end of the year sign, which 
extends under the mim. But there seems no way to contextually trigger 
the substitution of this variant relative to the year sign because of 
the intervening direction changes.


JH


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