[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
bug#56008: 29.0.50; image-mode buffer scrolled down automatically
From: |
Visuwesh |
Subject: |
bug#56008: 29.0.50; image-mode buffer scrolled down automatically |
Date: |
Thu, 16 Jun 2022 22:53:01 +0530 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/29.0.50 (gnu/linux) |
[வியாழன் ஜூன் 16, 2022 20:11] Eli Zaretskii wrote:
>> From: Visuwesh <visuweshm@gmail.com>
>> Cc: larsi@gnus.org, 56008@debbugs.gnu.org
>> Date: Thu, 16 Jun 2022 22:25:05 +0530
>>
>> [வியாழன் ஜூன் 16, 2022 18:49] Eli Zaretskii wrote:
>>
>> > What do you mean by "it was `save-window-excursion'"? what is "it" in
>> > this case?
>>
>> I thought the source of the random, unwarranted scrolling could be
>> `save-window-excursion' since it did come with the following warning,
>>
>> BEWARE: Most uses of this macro introduce bugs.
>> E.g. it should not be used to try and prevent some code from opening
>> a new window, since that window may sometimes appear in another frame,
>> in which case ‘save-window-excursion’ cannot help.
>
> We don't create new windows in this case, so that warning is not
> relevant.
>
> But save-window-excursion is indeed part of the puzzle, see below.
>
>> > And how did you see that this is not the case?
>>
>> Sorry, but it is close to a year since I looked at the source code. All
>> I remember is being annoyed by the bug despite removing the
>> `save-window-excursion' bit willy-nilly.
>>
>> [ This was all in ement.el's source code if I wasn't clear, BTW. ]
>
> I don't know what ement.el does and whether this is related, but
> here's what was happening in this case:
>
> . we invoke eww to fetch some URL
> . before it finishes to fetch the URL, we switch to another window
> . eww finishes fetching the URL and calls shr.el to render it
> . shr.el uses the selected window for rendering, and as part of
> that, it calls set-window-buffer to temporarily make the buffer in
> which it renders be the buffer of the selected window
> . set-window-buffer resets the window's hscroll and vscroll values
> . shr.el calls set-window-buffer inside save-window-excursion, but
> save-window-excursion didn't preserve the value of vscroll, and in
> addition shr.el called set-window-hscroll in one place that wasn't
> inside save-window-excursion
> . so both vscroll and hscroll of the window showing the image ended
> up with zero hscroll and vscroll
> . since image-mode overrides the usual definition of M-> with a
> command that works by setting the window's hscroll and vscroll,
> resetting these two makes the (mistaken) impression that the
> window was scrolled
> . the reason M-x and M-: appeared to "fix" the problem is that
> image-mode defines a window-configuration-change-hook that forces
> the display back to what it was -- this looked to us as if the
> problem was caused by some redisplay bug, something that took me
> some time to realize its being completely wrong
Thanks for the explanation, Eli! If I still the remember the ement.el
code, I think your commit _should_ fix the problem. But if it doesn't,
at least now I have a better idea of where to look. Thanks, again.
- bug#56008: 29.0.50; image-mode buffer scrolled down automatically, Visuwesh, 2022/06/16
- bug#56008: 29.0.50; image-mode buffer scrolled down automatically, Lars Ingebrigtsen, 2022/06/16
- bug#56008: 29.0.50; image-mode buffer scrolled down automatically, Lars Ingebrigtsen, 2022/06/16
- bug#56008: 29.0.50; image-mode buffer scrolled down automatically, Visuwesh, 2022/06/16
- bug#56008: 29.0.50; image-mode buffer scrolled down automatically, Eli Zaretskii, 2022/06/16
- bug#56008: 29.0.50; image-mode buffer scrolled down automatically, Lars Ingebrigtsen, 2022/06/16
- bug#56008: 29.0.50; image-mode buffer scrolled down automatically, Visuwesh, 2022/06/16
- bug#56008: 29.0.50; image-mode buffer scrolled down automatically, Eli Zaretskii, 2022/06/16
- bug#56008: 29.0.50; image-mode buffer scrolled down automatically, Visuwesh, 2022/06/16
- bug#56008: 29.0.50; image-mode buffer scrolled down automatically, Eli Zaretskii, 2022/06/16
- bug#56008: 29.0.50; image-mode buffer scrolled down automatically,
Visuwesh <=
- bug#56008: 29.0.50; image-mode buffer scrolled down automatically, Eli Zaretskii, 2022/06/16
- bug#56008: 29.0.50; image-mode buffer scrolled down automatically, Eli Zaretskii, 2022/06/16
- bug#56008: 29.0.50; image-mode buffer scrolled down automatically, Visuwesh, 2022/06/16
- bug#56008: 29.0.50; image-mode buffer scrolled down automatically, Eli Zaretskii, 2022/06/16
bug#56008: 29.0.50; image-mode buffer scrolled down automatically, Eli Zaretskii, 2022/06/16