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Re: Set-window-vscroll sometimes doesn't work
From: |
Eli Zaretskii |
Subject: |
Re: Set-window-vscroll sometimes doesn't work |
Date: |
Thu, 22 Oct 2020 19:05:01 +0300 |
> From: Yuan Fu <casouri@gmail.com>
> Date: Wed, 21 Oct 2020 15:05:26 -0400
> Cc: help-gnu-emacs@gnu.org
>
> But my point was that you shouldn't set window-start if you need to
> use a non-zero vscroll.
>
> It does: mwheel-scroll calls scroll-down/up, which calls
> window_scroll_pixel_based, which sets w->start
> (and it sets vscroll for tall image).
If you examine the code in window_scroll_pixel_based carefully, you
will see that it either sets vscroll or w->start, but never both.
> next-line and friends only vscroll when scroll-conservatively=0 and ARG=1,
> which allows it to get
> away from the problem I face (set-window-start and set-window-vscroll in the
> same time). I either
> implements smooth scrolling to only work when ARG=1 or I need to set both
> value at the same
> time.
>
> I don't understand why you say this. First, C-n works on tall images
> with arguments greater than 1. And second, I still don't understand
> why you need to set window-start, because vscroll should be enough for
> your needs, as far as I understand.
>
> C-n doesn’t smooth scroll on tall images when ARG > 1: The code checks for
> ARG = 1, if not, it doesn’t do
> line-move-partial. I also tried C-2 C-n, no smooth scrolling.
What do you mean by "smooth scrolling" here? If I invoke C-2 C-n" on
a large image, the image gets scrolled by the amount of pixels that is
equivalent to 2 screen lines. Isn't that what you see?
> I thought vscroll is a relative measure and is measured against window-start.
> And it kind of makes sense to
> set a window start as the basis and set vscroll based on that. So I kind of
> assumed that window-start is
> always at least partially visible and vscroll is always less than the height
> of the first line. Now, if I throw away
> window-start and scrolls entirely by vscroll, will there be any problems?
> Like, does anyone relies on
> window-start being visible? I felt like that’s what people uses to get the
> first line displayed in the window.
When vscroll is so large that the window-start point is entirely not
visible, you should move window-start so it becomes visible. But that
shouldn't be a problem, because it means you've scrolled the entire
image off-screen.
- Re: Set-window-vscroll sometimes doesn't work, (continued)
- Re: Set-window-vscroll sometimes doesn't work, Yuan Fu, 2020/10/22
- Re: Set-window-vscroll sometimes doesn't work, Eli Zaretskii, 2020/10/23
- Re: Set-window-vscroll sometimes doesn't work, Yuan Fu, 2020/10/23
- Re: Set-window-vscroll sometimes doesn't work, Eli Zaretskii, 2020/10/23
- Re: Set-window-vscroll sometimes doesn't work, Yuan Fu, 2020/10/23
- Re: Set-window-vscroll sometimes doesn't work, Eli Zaretskii, 2020/10/24
- Re: Set-window-vscroll sometimes doesn't work, Jens C . Jensen, 2020/10/26
- Re: Set-window-vscroll sometimes doesn't work, Eli Zaretskii, 2020/10/26
- Re: Set-window-vscroll sometimes doesn't work, Yuan Fu, 2020/10/27
- Re: Set-window-vscroll sometimes doesn't work, Eli Zaretskii, 2020/10/27
- Re: Set-window-vscroll sometimes doesn't work,
Eli Zaretskii <=