Re: redisplay system of emacs

[Eli Zaretskii <eliz@gnu.org>]

> From: Paul R <paul.r.ml@gmail.com>
> Cc: Lennart Borgman <lennart.borgman@gmail.com>,  alinsoar@voila.fr,  Eli Zaretskii <eliz@gnu.org>,  Emacs-devel@gnu.org
> Date: Fri, 29 Jan 2010 11:04:42 +0100
> 
> Hello,
> 
> > Note that mozilla's display engine makes some dramatically different
> > assumptions about what is important for the display engine to do.
> 
> 
> I found a related discussion in a previous thread, mid-2009 :
> 
>   http://lists.gnu.org/archive/html/emacs-devel/2009-07/threads.html#00344

Yeah, this pops up from time to time.

> As many emacs youngsters, I feel that emacs really uses too much
> home-made code. Surprisingly, Emacs does not benefit that much from the
> free software ecosystem.

That's a pretty general assessment.  Any data points other than the
display engine?

> This is certainly connected to the fact that it
> has been ahead of its time in many aspects, so it had to build its own
> bricks without waiting for others to provide them. But in the meantime
> some things has changed, high quality generic free software fragments
> has entered the game. Entrusting them rather than home-made code would
> certainly be a big job, but would instantly enlarge emacs (indirect)
> contributors list.

"Big job" is an understatement of the century.  Most of these "generic
free software fragments" are not written with Emacs peculiar
requirements in mind, and don't have a Lisp API.

Where these issues don't matter, Emacs does use existing software,
like with the font support and display-specific back ends that
actually render the characters on glass.

> The performance of those engines has gotten surprisingly good, and is
> still improving at a very fast rate. I would be interested to have some
> real-case benchmarks.

One of the most important benchmarks would be inserting or deleting a
small amount of text in a very large document.  As an interactive
editor, Emacs has to deal with this most of the time.  Not sure if
those other display engines are optimized to this modus operandi.