Re: API to control the GTK parts from Elisp

[Basile Starynkevitch <basile@starynkevitch.net>]

On 8/25/23 03:47, Po Lu wrote:
> Sébastien Gendre <seb@k-7.ch> writes:
>
>> Hello world!
>>
>> On GNU/Linux, the GUI version use GTK for some parts, like the
>> header-bar, the tool-box, etc.
>>
>> Is it possible to control these GTK elements from Elisp ? Like modifying
>> their CSS rules or the GTK theme applied ?
>>
>>
>> Best regards
> Such features aren't available in Emacs Lisp.


But recent GNU emacs is (on Linux) already using dlopen and dlsym (in 
file emacs/src/dynlib.c)

So I guess it should not be too difficult to customize your GNU emacs 
source code (or its GNU Elisp scripts) to add the necessary Elisp 
primitives to control these GTK elements. Some C and Elisp code is needed.

A practical possibility (see https://arxiv.org/pdf/1109.0779.pdf ...) 
could even be to generate -in some temporary file- some short C code 
dynamically on the fly (using your Elisp scripts), compile that short C 
temporary code as a plugin, then have it dlopen-ed and dlsym-ed. Current 
Linux laptops are fast enough to make that compatible with human 
interaction. (e.g. generating 200 lines of C and compiling it into a 
shared object can be done in a fraction of a second, and is doable 
perhaps once every few keystrokes handed by GNU emacs).

Another practical possibility could be to develop (in a few hundred 
lines of C) your background process handling these.   The GNU emacs 
process would start it at initialization and communicate with it (e.g. 
thru pipes or AF_UNIX sockets). Proof of concept code on 
https://github.com/bstarynk/misc-basile/blob/master/manydl.c and 
https://github.com/bstarynk/misc-basile/blob/master/execicar.c ...


PS. My pet open source project is the RefPerSys inference engine (see 
code on https://github.com/RefPerSys/RefPerSys/ ....)


-- 

Basile Starynkevitch                  <basile@starynkevitch.net>
(only mine opinions / les opinions sont miennes uniquement)
92340 Bourg-la-Reine, France
web page: starynkevitch.net/Basile/