Re: [Silgraphite-devel] Re: Pango and SILGraphite

[Peter_Constable sil org]

[I'm not on the gtk-i18n list, so if that list accepts posts only from
members, could some member please forward.]

Hi, there, Edward!


On 01/24/2003 06:21:37 PM Edward Cherlin wrote:

>So is it easier to code modules for these nine scripts plus any others
that
>may turn up, or to make use of a general-purpose engine that requires the
>design of some font tables in order to support a new script?

Well, the general-purpose engine (Graphite) exists! It's not question of
making it, but getting it supported in various applications, commonly-used
support libraries or application frameworks.


>The complexities
>of the script have to be encoded somehow, whether as program or data

In each of AAT, OpenType and Graphite, both are involved. The differences
are that OpenType implementations rely on a lot of script-specific
information being coded in software (benefit: it doesn't have to be
duplicated in multiple fonts; shortcoming: any given script won't be
supported until the software is updated), whereas the software involved
with AAT and Graphite has little script-specific information that's
hard-coded (there is some, such as most or all of the bidi algorithm).


>, so it
>is not clear whether either approach really saves work.

There is work to be done either way; the differences are in who has to do
the work -- font developers or software developers -- and in how the work
gets packaged and distributed. From the perspective of users of a complex
script that's not widely supported, it's much easier, and more accessible
and feasible to develop a font than to get software revised. Moreover, if
there is a lot of software that can utilise a general-purpose-engine
approach, then there's less work and a lot more payoff for them: if they
develop a font, then their script can be supported in multiple applications
immediately



>According to SIL's experts, several of the complex scripts, such as
Burmese,
>cannot be rendered completely correctly from TrueType or ordinary OpenType
>fonts.

Well, there's no debate that plain-vanilla TrueType can't deal with any
complex script adequately. As for OpenType, it can do quite a bit, though
some have questioned whether it can hold up in some situations. I'm not
sure if any of us in SIL has flatly said that several complex scripts
cannot be rendered completely correctly using OpenType, though I suspect
some of us might have said that implementing certain behaviours and,
perhaps, certain scripts can be a pain in OpenType.


>SIL has created a new kind of table to add to its own OpenType fonts,
>and has been discussing the possibility of getting those tables added to
the
>OT standard.

No, we have not defined any additions to OpenType. We *have* defined a
TrueType extension (additional tables), namely the Graphite-related tables,
that are an alternative to either the OpenType or AAT extensions of
TrueType.



>I don't know the technical issues that SIL is concerned with

Our primary concern in developing Graphite has been to see that uses of a
not-widely-supported script can get their script supported as easily as
possible, and specifically without having to re-write software (since
that's the thing that is least accessible to most users, even in an
open-source context).



- Peter


---------------------------------------------------------------------------
Peter Constable

Non-Roman Script Initiative, SIL International
7500 W. Camp Wisdom Rd., Dallas, TX 75236, USA
Tel: +1 972 708 7485