Re: [gtk-i18n-list] Unicode PUA supporting issue in gtk+/pango

[mpsuzuki hiroshima-u ac jp]

On Sat, 24 Dec 2005 12:53:34 +0800
Chia-I Wu <b90201047 ntu edu tw> wrote:

>> >This is another and big problem, not related to fonts.  You can imagine,
>> >after a system switches to unicode 4.1, you will hear complaints such as
>> >"I can see the characters (in a document or of a filename).  But when I
>> >search, it just don't match!"
>> 
>> >IMHO, we can have a script to convert all filenames, at the post-install
>> >time on package upgrade.  As for the documents, users should manually
>> >convert them, if he/she needs searchability.
>> 
>> I think it's still font-related issue. The utilization
>> of PUA codepoint is induced by the font. The "displayable"
>> PUA codepoint is determined by the font (or, it's determined
>> by some national standards? if so, please let me know),
>
>No, not by the font.  There indeed are standards:
>http://www.info.gov.hk/digital21/eng/hkscs/mapping_table.html

Please let me know the situation of update cycle of HKSCS and
HKSCS-compliant fonts. Reading the inclusion policy of HKSCS
at

http://www.info.gov.hk/digital21/eng/hkscs/applicn.html#application

I think HKSCS will be used as a sum of temporal charset of
the characters that are not included in Unicode (at that time)
and pushed for future Unicode (at that time). So it may be very
often revised. I heard of GCCS-1998, HKSCS-1999, HKSCS-2001,
and HKSCS-2004. Nothing to say, even if the charset/mapping
table of new HKSCS is published, the release of the font for
new HKSCS will be delayed (especially high-quality scalable
fonts). Therefore, even if we ignore the possibility that
some fonts have all characters of HKSCS-2001 and a part of
HKSCS-2004, we have to use HKSCS-2001 mapping table for the
font that is compliant to HKSCS-2001 and not to HKSCS-2004.
If we use HKSCS-2004 mapping table and HKSCS-2001 fonts,
some PUA codepoints are mapped to undisplayable public codepoints,
coversion scripts generate undisplayable string. Therefore,
I think, still we have to care which standards the font is
compliant...?

>Some characters in (Taiwan-)BIG5 are also mapped to PUA.  The `P' here
>means Taiwan.  A codepoint in PUA may be assigned different glyphs in
>different areas.
>
>Therefore, even if HKSCS contains all characters defined by
>(Taiwan-)BIG5, a font to be used in HK can _not_ be used in Taiwan.
>
>(Well, it _can_ actually, but not under pango.)

Interesting. Could you tell me the framework to use the font
in Taiwan?

Regards,
mpsuzuki