From: Christopher Fynn (email@example.com)
Date: Tue Aug 23 2005 - 23:44:27 CDT
John Hudson wrote:
> But if you ask anyone at Microsoft and Adobe, they will tell you that
> this is the expectation, because separation of common language shaping
> from glyph processing is one of the key design philosophies of OpenType.
> This has been stated so many times in so many places, beginning with the
> OT Jamboree at Microsoft way back in 1998, that I'm surprised we're
> having this conversation.
When first reading about OpenType, I think it is still fairly easy for
people to get the impression that, if there are lookups in the font,
almost any feature will be applied to to any character by the shaping
engine. It is not made clear enough that for non-Latin complex script
rendering the logic for each particular script is built into the shaping
engine - and that for any given script only a particular (defined)
sub-set of OT features is automatically applied by the shaping engine.
If one wants to Microsoft's shaping engine (Uniscribe) for a particular
script then that script has to be already supported (or one has to wait
for Microsoft to add support) - and, in the font, one has to use lookups
only under the particular sub-set of OT features Uniscribe actually
supports for that script.
For unsupported scripts, applying OT shaping to PUA characters and so on
in MS Windows there aren't many choices: 1) Try to find an application
supporting a font and shaping system where you can put all the necessary
logic into the font tables (GRAPHITE, AAT) and use that. 2) Find an
application using an open source OpenType shaping engine (like Pango or
ICU) and add your own code to enable shaping support for the script /
characters you need. 3) Wait for Microsoft to add support for your
script in Uniscribe.
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