Re: How to convert char from Emacs-20 internal to UTF-8?

[Adrian Robert <arobert@cogsci.ucsd.edu>]

On Mar 16, 2005, at 12:19 PM, Stefan Monnier wrote:

>> I apologize for the "retro" question, but I was wondering if there 
>> was an
>> easy way to convert a character in the Emacs-20 internal 19-bit 
>> encoding
>> (from FAST_GLYPH_CHAR(glyph)) to UTF-8 (preferable) or straight 
>> Unicode.
>> I'd like to do it fully within C if possible, and it needs to be 
>> efficient.
>
> Since Emacs-21's internal chars are a superset of Emacs-20's internal 
> chars,
> you can just use Emacs-21's facilities like (encode-coding-string <str>
> 'utf-8) or (encode-char <char> 'ucs).

Thanks.  Are the encode-coding-string and encode-char functions a) fast 
enough to be used inside of dumpglyphs() for screen rendering and b) 
something I can easily lift out of 21 and backport to 20?  I'm asking 
because this is for a GNUstep/OS X interface for emacs 20 
(http://emacs-on-aqua.sf.net/), and while we'd like to bring it up to 
date to work with the coming emacs-22 (where I assume this problem 
disappears completely), this is a large job and we'd like to have 
support for 2-byte font and other i18n rendering in the meantime.  (In 
the OpenStep APIs, conversions to native font encoding are handled 
internally, so we don't need all of CCL's generality, but we need to 
get characters in UTF-8 or unicode to give to the APIs in the first 
place.)