On Thu, Nov 29, 2001 at 08:08:55PM +0900, Tomohiro KUBOTA wrote:
> Hi,
> 
> At Thu, 29 Nov 2001 12:08:02 +0700,
> Theppitak Karoonboonyanan wrote:
> 
> > In fact, they should have been said to be restricted to "UCS" support.
> > The special treatment for combining characters can be considered as
> > "implementation level 2" in ISO/IEC 10646-1.
> 
> Sorry, I don't understand your opinion well.  You said that "-m-" and
> "-c-" fonts should be exactly fixed-width, without negative expand nor
> offset.  Then, what fonts should terminal emulators (and other column-
> based softwares) use?  "-m-*-tis620-0" or "-c-*-tis620-0" fonts which
> are exactly fixed-width?  Or, "-p-*-tis620-0" with negative expand
> but virtually fixed-width?

IMO, "-c-*-tis620-0" fonts which are exactly fixed-width, plus special
treatment of UCS combining characters, and multiple-character screen
cells.

According to X spec, -p- fonts are not guaranteed to fit in columns,
and -m- fonts are not safe to overlay glyphs in a single cell without
overcrossing.

Hmm.. In fact, I have once proposed the three modes of rendering (with
illustration) at http://www.links.nectec.or.th/~thep/thaisupp/#OM_Render
in the "Stacking of combining characters" subsection:

- Proportional fonts: sequential advancement with the aids of
  negative-expand glyphs for combining characters.
- Monospace fonts: no stacking at all.
- CharCell fonts: special treatment of combining characters.

> I read your web page that advocate usage of "tis620-0" fonts instead
> of "tis620.xxxx-x" fonts.  However, the page doesn't mention detailed
> technical design of such fonts. 

Sorry about that. The page is just under construction.  Currently,
tis620-2.enc is already in XFree86 CVS. That's all you can get for now.
I'll add more info soon. :->

> (The page 
> http://linux.thai.net/~thep/th-xwindow/ seems not accessable now.
> Could you please check the page?)

Please refer to another mirror at
http://www.links.nectec.or.th/~thep/th-xwindow/ for the time being.

> Anyway, I think that native Thai people should have a political voice
> for the detailed technical design of tis620.0 fonts, because other people
> (including I) don't know how deeply Thai people depend on the de-facto
> standard of fonts.

We just try to conform to international standards as much as possible,
so that we can benefit from existing tools and applications without
much hacking.

The tis620-[012] convention is a concensus that comes up to adjust
the existing practices into existing specs and standards. So, the
technical details are to be extracted from current Windows and Mac
font designs.

> Of course, if Thai people think the modification of the fonts doesn't
> cost very much, we (people from all over the world) can attend the
> discussion on the detailed technical design of Thai fonts.

That's good. :) But you know it may also require the implementations of
applications to be more strict to Unicode. And we will also adjust
ourselves to the standards.

I will prepare the detailed design soon.

Regards,
-Thep.
-- 
Theppitak Karoonboonyanan
Information Research and Development Division, NECTEC
http://www.links.nectec.or.th/~thep/  mailto:[EMAIL PROTECTED]
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