On 08/19/2011 11:21 AM, Michael Everson wrote:
Directionality is a very deep property. A CSUR LTR script works fine out of the box on
all platforms at least as far as directionality goes. A CSUR RTL script simply can't, and
do you really think that "defining the properties" will effectively override
the system-level expectations for LTR PUA on multiple platforms?
Very very very unlikely.
Pretty sure it can't. I remember a discussion about the directionality
of the PUA some time ago, and I thought it was here, but looking back it
may have been on another mailing list. Here it is, from the
Fontforge-users mailing list (fontforge is an open-source font-design
program). Back in March:
Khaled Hosny ([email protected]) wrote:
On Tue, Mar 01, 2011 at 07:43:13PM +0100, Pocok Előd wrote:
Could you tell me if there is a solution for changing the writing direction to
> RTL while using the Latin area?
Not in the font itself, OpenType engines relay on character's Unicode
properties for directionality (using Unicode BiDi algorithm). But you
can force a string of text to be RTL by surrounding it with U+202E
(right to left override mark) and U+202C (pop directional formatting
mark).
It's pretty disingenuous to say "Well, if you want a private-use RTL
script, you should be prepared to write an engine that can render it,"
ignoring the fact that LTR people can get by with just a font. Why
should it be so much harder to write RTL?
~mark
