Re: Adding Tai Tham Script to GNU/Linux Distribution's Version of Emacs

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sun, 15 Mar 2015 12:32:20 +0000
> From: Richard Wordingham <richard.wordingham@ntlworld.com>
> 
> I am currently using a distribution's latest version of Emacs.
> The distribution is Ubuntu 12.04, precise pangolin, and the version of
> Emacs it currently delivers is 23.3.1.  Is it 'simple' to add complex
> text layout (CTL) for the Tai Tham script on non-Windows systems?

I recommend to get Emacs 24, as its support of Unicode is much better.

> I hope that all I have to do is to:
> 
> 1) Modify fontset.el to add the script.
> 2) Replace fontset.elc
> in /usr/share/emacs/23.3/lisp/international/fontset.elc by the modified
> version of fontset.el from the source description.
> 3) Augment the m17n library to use a HarfBuzz-compatible Tai Tham
> font.  I have such a font, and it works fine with Emacs when CTL is not
> needed.
> 
> One of my worries is that I may have to update characters.el and
> recompile Emacs.
> 
> I already have a working Emacs input method for the Tai Tham script.

Only this should be necessary:

  1) Modify fontset.el to add the script.

There are examples in the Emacs manual's node "Modifying Fontsets", go
by them.  AFAIU, either the 1st or the last one should fix the issue
for you, assuming you have a suitable font.

Caveat: I only tried these examples with Emacs 24, not with 23.3.