Re: Scrolling commands and skipping redisplay, was: Re: emacs rendering comparisson between emacs23 and emacs26.3

[Dmitry Gutov]

On 21.04.2020 17:02, Eli Zaretskii wrote:

> > A certain amount of work that's also part of redisplay.
>
> I suggest to use a common terminology, otherwise we will just confuse
> each other.  Let's agree to call "redisplay" only what happens when
> Emacs calls one of the two functions: redisplay_internal and
> echo_area_display.  OK?  Redisplay calls many functions, including
> fontification-functions, but those functions themselves are not to be
> called "redisplay", because they don't display anything.

Do scrolling commands and/or code that calls posn-at-point do anything 
else common with redisplay other than fontification functions?

For instance, converting the buffer text into some other structure that 
rendering the window will be based on. I think you called it a "glyphs 
table" or something like that.

If *that* work (together with fontification) is usually what takes the 
most time during redisplay, there could be some simple cache added on to 
of it, which would make skipping redisplay unnecessary in cases when the 
command would pre-fill such cache.

Otherwise, this idea is a dud.