Re: [Bug: 21.4.19] smooth vscroll-{up,down}

Re: [Bug: 21.4.19] smooth vscroll-{up,down}

[Jérôme Bouat]

But emacs can move smoothly the window,
it is simply not mapped in 'next-line' function.
For the expected result, make emacs evaluate:
(dotimes (i 10) (set-window-vscroll nil (* i 0.1)) (sit-for 0.05))

On Fri, 2007-06-15 at 03:42 +0900, Stephen J. Turnbull wrote:
> Jérôme Bouat writes:
> 
>  > Could you add an option for smooth scrolling
> 
> Refactoring window configuration and redisplay to be more friendly to
> pixel-based scrolling has been discussed, but AFAIK nobody is actively
> working on it, and AFAIK it's not currently possible in any version of
> XEmacs.  Contributions welcome.
> 
> 

Re: [Bug: 21.4.19] smooth vscroll-{up,down}

[Stephen J. Turnbull]

Jérôme Bouat writes:

 > But emacs can move smoothly the window,
 > it is simply not mapped in 'next-line' function.
 > For the expected result, make emacs evaluate:
 > (dotimes (i 10) (set-window-vscroll nil (* i 0.1)) (sit-for 0.05))

`set-window-vscroll' is an Emacs function not present in XEmacs.  Nor
is there equivalent functionality as far as I know.

Re: [Bug: 21.4.19] smooth vscroll-{up,down}

[Johan Bockgård]

>  > (dotimes (i 10) (set-window-vscroll nil (* i 0.1)) (sit-for 0.05))

Great, that hung my Emacs. A recipe:

emacs -Q -eval '(progn (setq scroll-conservatively 1) (set-window-vscroll nil 1))'

-- 
Johan Bockgård

Re: [Bug: 21.4.19] smooth vscroll-{up,down}

[David Kastrup]

Jérôme Bouat <jerome.bouat@wanadoo.fr> writes:

> But emacs can move smoothly the window,
> it is simply not mapped in 'next-line' function.
> For the expected result, make emacs evaluate:
> (dotimes (i 10) (set-window-vscroll nil (* i 0.1)) (sit-for 0.05))

It must be noted that while this Emacs (not XEmacs) code somewhat
works, it is not integrated with the display engine in a manner that
will cause sane and smooth recentering and cursor movement behavior.

Also, true smooth scrolling works by whole pixel amounts, not "line
fractions", and the scrolling happens at vertical retrace time for
best effect.

The complex display engine of Emacs (can't vouch for XEmacs) is not
all too well suited for this sort of pixel-based action.  If it were,
scrollbars would behave "more naturally" already.

-- 
David Kastrup, Kriemhildstr. 15, 44793 Bochum