On 08/22/2011 04:34 PM, Behdad Esfahbod wrote:
On 08/22/11 06:53, Shriramana Sharma wrote:
>
>
> 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 ?
Depends on your specific shaping engine logic. OpenType assumes native
direction per script. So if you have Arabic text between LRO/PDF, you have to
reverse the order then apply OpenType shaping. Other engines may decide to
handle these differently. But the general statement is true: ligatures are
visual artifacts and hence only form in one direction, not the other (except
if it's, say, the "ff" ligature).
Hi Behdad. I only asked whether the OT *tables* would contain the
entries in the logical order or the visual order. Clearly it would still
be the visual order (but Philippe Verdy seemed to imagine/suggest
otherwise).
It is clear that in the *script itself* the ligature would form in the
direction of writing.
--
Shriramana Sharma
