Recentering during article scrolling with scroll-margin

Recentering during article scrolling with scroll-margin

[Ralf Angeli]

Hi,

the handling of `scroll-margin' has recently changed a bit in Emacs CVS
and recentering seems to happen more agressively now.  This becomes a
problem if `scroll-margin' is greater than 0 and one is scrolling an
article with <RET>.  When the bottom of the article is reached the last
line will not stay at the bottom of the window but jump to the middle of
it.

The recentering is triggered by the statement
(move-to-window-line -1)
in `gnus-article-next-page'.  It is usually countered by
`gnus-article-next-page-1', but not at the end of an article where the
latter function will not be called.

The problem can be circumvented by changing the above statement to
(move-to-window-line (- -1 scroll-margin))

If necessary I can provide a change log entry for such a change.

-- 
Ralf

Re: Recentering during article scrolling with scroll-margin

[Katsumi Yamaoka]

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>>>>> Ralf Angeli wrote:
> the handling of `scroll-margin' has recently changed a bit in Emacs CVS
> and recentering seems to happen more agressively now.  This becomes a
> problem if `scroll-margin' is greater than 0 and one is scrolling an
> article with <RET>.  When the bottom of the article is reached the last
> line will not stay at the bottom of the window but jump to the middle of
> it.

> The recentering is triggered by the statement
> (move-to-window-line -1)
> in `gnus-article-next-page'.  It is usually countered by
> `gnus-article-next-page-1', but not at the end of an article where the
> latter function will not be called.

> The problem can be circumvented by changing the above statement to
> (move-to-window-line (- -1 scroll-margin))

I tried (setq scroll-margin 3) on the latest Emacs 22.0.50 and
23.0.60 and confirmed this fix is necessary for the case where
`gnus-article-over-scroll' is nil (the default).

> If necessary I can provide a change log entry for such a change.

Please provide it and I'll commit the slightly modified one like:


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(Note that there is no `scroll-margin' control in XEmacs.)

BTW, another problem related to `scroll-margin' seems to have
been solved in the latest Emacs 22.0.50 and 23.0.60:

>>>>> In <b4m4pbs7c2e.fsf@jpl.org> Katsumi Yamaoka wrote:
> The problem is, in short, that the cursor in the Gnus summary
> buffer jumps to a subject line that is not for the article being
> displayed just after selecting the article by the `g' command, if
> `scroll-margin' is a non-zero value (actually it is 3).  You may
> need to have many articles in threads and to expand the summary
> window to a certain height.

Regards,

Re: Recentering during article scrolling with scroll-margin

[Ralf Angeli]

* Katsumi Yamaoka (2008-08-11) writes:

> I tried (setq scroll-margin 3) on the latest Emacs 22.0.50 and
> 23.0.60 and confirmed this fix is necessary for the case where
> `gnus-article-over-scroll' is nil (the default).

Thanks for confirming.

>> If necessary I can provide a change log entry for such a change.
>
> Please provide it and I'll commit the slightly modified one like:
>
> (move-to-window-line (if (featurep 'xemacs) -1 (- -1 scroll-margin)))
>
> (Note that there is no `scroll-margin' control in XEmacs.)

Okay, here is a change log entry and a patch:

2008-08-11  Ralf Angeli  <angeli@caeruleus.net>

	* gnus-art.el (gnus-article-next-page): Respect `scroll-margin' when
	moving point to the bottom of the window in order to avoid recentering.


--- gnus-art.el.~7.279.~	2008-08-03 12:03:34.000000000 +0200
+++ gnus-art.el	2008-08-11 18:30:35.000000000 +0200
@@ -6113,7 +6113,7 @@
 If end of article, return non-nil.  Otherwise return nil.
 Argument LINES specifies lines to be scrolled up."
   (interactive "p")
-  (move-to-window-line -1)
+  (move-to-window-line (if (featurep 'xemacs) -1 (- -1 scroll-margin)))
   (if (and (not (and gnus-article-over-scroll
 		     (> (count-lines (window-start) (point-max))
 			(+ (or lines (1- (window-height)))


-- 
Ralf

Re: Recentering during article scrolling with scroll-margin

[Katsumi Yamaoka]

>>>>> Ralf Angeli wrote:
> 2008-08-11  Ralf Angeli  <angeli@caeruleus.net>

>         * gnus-art.el (gnus-article-next-page): Respect `scroll-margin' when
>         moving point to the bottom of the window in order to avoid recentering.

Thanks.  I've committed it.

Re: Recentering during article scrolling with scroll-margin

[Reiner Steib]

On Mon, Aug 11 2008, Ralf Angeli wrote:

> 	* gnus-art.el (gnus-article-next-page): Respect `scroll-margin' when
> 	moving point to the bottom of the window in order to avoid recentering.
[...]
> +  (move-to-window-line (if (featurep 'xemacs) -1 (- -1 scroll-margin)))

Should we test for `scroll-margin' instead of (featurep 'xemacs)?
E.g. (and (boundp 'scroll-margin) (numberp scroll-margin))?

Bye, Reiner.
-- 
       ,,,
      (o o)
---ooO-(_)-Ooo---  |  PGP key available  |  http://rsteib.home.pages.de/

Re: Recentering during article scrolling with scroll-margin

[Katsumi Yamaoka]

>>>>> In <87vdy4buyf.fsf@marauder.physik.uni-ulm.de>
>>>>>	Reiner Steib <reinersteib+gmane@imap.cc> wrote:

>> +  (move-to-window-line (if (featurep 'xemacs) -1 (- -1 scroll-margin)))

> Should we test for `scroll-margin' instead of (featurep 'xemacs)?
> E.g. (and (boundp 'scroll-margin) (numberp scroll-margin))?

That's right if XEmacs team plan to introduce the scroll-margin
control in the future.  But the reason I arbitrarily decided to
use (featurep 'xemacs) is that I don't think so.  It also makes
the source code be clean and makes the byte code be a little bit
fast.  Is it a wrong approach?  In other words, does XEmacs plan
to have the scroll-margin control in the future?

Regards,