Re: RTL PUA?

On 08/22/2011 12:53 AM, Shriramana Sharma wrote:
> On 08/22/2011 12:01 AM, Peter Constable wrote:
>> If you mean a rule to substitute [g1 g2] with [g3] won't apply if the
>> sequence processed by the OpenType Layout lookup processor is [g2
>> g1],
>
> Peter, actually I suspect Philippe is thinking that in the case of
> RTL, the *glyphs* are placed in reverse order and then he is asking
> how can the ligation take place.
>
> While I don't know much about RTL scripts, if the logic order is ALEF
> + LAMED, but the presentation order is LAMED + ALEF *because of the
> RTL nature* do you write the rule as ALEF + LAMED =
> ALEF_LAMED_LIGATURE or LAMED + ALEF = ALEF_LAMED_LIGATURE ?
>

I'm not certain I understand the question, but if I have it right... The
logic order is ALEF + LAMED, and the presentation... places those in a
right-to-left sequence, shall we say (since talking about the
presentation *order* is confusing here). The font table contains the
lookup that ALEF + LAMED ⇒ ALEF_LAMED_LIGATURE. It all goes according
to the logical order, since the presentation "order" isn't really an
order, it's just a direction. (this is different from things like
devanagari short-i vowel, which "moves" with respect to the other
letters in the script.)

~mark
Received on Mon Aug 22 2011 - 00:30:38 CDT