Re: Emacs design and architecture

[Gerd Möllmann]

Dmitry Gutov <dmitry@gutov.dev> writes:

> On 15/09/2023 12:32, Gerd Möllmann wrote:
>> I think it would maybe be good to think about the following:
>> Random thoughts about a parallel redisplay, from a height of 10 km.
>> What currently happens to bring changes to the screen is that
>> redisplay
>> is called quite frequently in the course of processing input for
>> example.  Redisplay determines what part of the a "model" (buffer) has
>> changed, if any.  It makes sure that all info it needs to proceed is
>> available; think jit-lock, i.e. it calls Lisp. Because redisplay is
>> called frequently, it must minimize what it does, which is the reason
>> for the complicated optimizations there.
>> Whatever is done in the end, I think it would first be necessary to
>> change this general principle, so that layout/drawing whatever can
>> happen in parallel.  Without that, I suspect redisplay would get too
>> slow, or would finally collapse to a black hole by its complexity.
>
> I think it'd be an interesting project to study how an existing Emacs
> could output into a web page. Or a web driver, etc. How a "toolkit
> port" into HTML/JS could work.
>
> That system is historically more complex than what you described,
> including lots of callbacks, e.g. it might be possible to implement
> jit-lock using the 'DOMContentLoaded' and 'scroll' events.
>
> Consequently, though, parallel layout has been historically a hard
> problem for web browsers, but the current engines do that, at least to
> an extend (I think that was one of the selling features of Servo,
> later incorporated into Gecko). Complexity is definitely an issue,
> though.

Maybe it would be worth looking at emacs-ng

  https://github.com/emacs-ng/emacs-ng

The README lists the feature

  Webrender

  WebRender is a GPU-based 2D rendering engine written in Rust from
  Mozilla. Firefox, the research web browser Servo, and other GUI
  frameworks draw with it. emacs-ng use it as a new experimental graphic
  backend to leverage GPU hardware.