* set-window-vscroll causes infinite loop in redisplay
@ 2003-02-24 1:31 Kim F. Storm
2003-02-24 15:47 ` Kim F. Storm
2003-02-26 9:47 ` Richard Stallman
0 siblings, 2 replies; 5+ messages in thread
From: Kim F. Storm @ 2003-02-24 1:31 UTC (permalink / raw)
This is with CVS head on GNU/Linux under X.
1) start emacs
emacs -q
2) get rid of splash screen
RET
3) In scratch buffer, enter:
(set-window-vscroll nil 0.5) C-j
4) (try to) move cursor to the first (partially visible) line.
C-p C-p C-p C-p C-p C-p C-p C-p
5) emacs loops.
The following patch fixes this. I'll install it tomorrow unless
someone finds a better fix.
Index: xdisp.c
===================================================================
RCS file: /cvsroot/emacs/emacs/src/xdisp.c,v
retrieving revision 1.806
diff -c -r1.806 xdisp.c
*** xdisp.c 18 Feb 2003 00:17:17 -0000 1.806
--- xdisp.c 24 Feb 2003 00:31:05 -0000
***************
*** 10821,10826 ****
--- 10821,10834 ----
if (!make_cursor_line_fully_visible (w))
{
+ /* If vscroll is non-zero, and the cursor is on the top line,
+ disable vscroll, and retry. */
+ if (w->vscroll < 0 && w->cursor.y < 0)
+ {
+ w->vscroll = 0;
+ clear_glyph_matrix (w->desired_matrix);
+ }
+
/* If centering point failed to make the whole line visible,
put point at the top instead. That has to make the whole line
visible, if it can be done. */
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: set-window-vscroll causes infinite loop in redisplay
2003-02-24 1:31 set-window-vscroll causes infinite loop in redisplay Kim F. Storm
@ 2003-02-24 15:47 ` Kim F. Storm
2003-02-25 13:34 ` Kim F. Storm
[not found] ` <87u1et7mf2.fsf@computer.localdomain>
2003-02-26 9:47 ` Richard Stallman
1 sibling, 2 replies; 5+ messages in thread
From: Kim F. Storm @ 2003-02-24 15:47 UTC (permalink / raw)
storm@cua.dk (Kim F. Storm) writes:
> This is with CVS head on GNU/Linux under X.
>
> 1) start emacs
>
> emacs -q
>
> 2) get rid of splash screen
>
> RET
>
> 3) In scratch buffer, enter:
>
> (set-window-vscroll nil 0.5) C-j
>
> 4) (try to) move cursor to the first (partially visible) line.
>
> C-p C-p C-p C-p C-p C-p C-p C-p
>
> 5) emacs loops.
>
>
>
> The following patch fixes this. I'll install it tomorrow unless
> someone finds a better fix.
I think the following fix is slightly better -- it retries the
recenter if vscroll was enabled. But it probably doesn't make much
visible difference...
Index: xdisp.c
===================================================================
RCS file: /cvsroot/emacs/emacs/src/xdisp.c,v
retrieving revision 1.807
diff -c -r1.807 xdisp.c
*** xdisp.c 24 Feb 2003 07:57:55 -0000 1.807
--- xdisp.c 24 Feb 2003 14:46:05 -0000
***************
*** 10822,10827 ****
--- 10822,10835 ----
if (!make_cursor_line_fully_visible (w))
{
+ /* If vscroll is enabled, disable it and try again. */
+ if (w->vscroll)
+ {
+ w->vscroll = 0;
+ clear_glyph_matrix (w->desired_matrix);
+ goto recenter;
+ }
+
/* If centering point failed to make the whole line visible,
put point at the top instead. That has to make the whole line
visible, if it can be done. */
--
Kim F. Storm <storm@cua.dk> http://www.cua.dk
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: set-window-vscroll causes infinite loop in redisplay
2003-02-24 15:47 ` Kim F. Storm
@ 2003-02-25 13:34 ` Kim F. Storm
[not found] ` <87u1et7mf2.fsf@computer.localdomain>
1 sibling, 0 replies; 5+ messages in thread
From: Kim F. Storm @ 2003-02-25 13:34 UTC (permalink / raw)
storm@cua.dk (Kim F. Storm) writes:
> I think the following fix is slightly better -- it retries the
> recenter if vscroll was enabled. But it probably doesn't make much
> visible difference...
I just committed the fix.
--
Kim F. Storm <storm@cua.dk> http://www.cua.dk
^ permalink raw reply [flat|nested] 5+ messages in thread
[parent not found: <87u1et7mf2.fsf@computer.localdomain>]
* Re: set-window-vscroll causes infinite loop in redisplay
[not found] ` <87u1et7mf2.fsf@computer.localdomain>
@ 2003-02-26 0:20 ` Kim F. Storm
0 siblings, 0 replies; 5+ messages in thread
From: Kim F. Storm @ 2003-02-26 0:20 UTC (permalink / raw)
Cc: emacs-devel
"D. Goel" <deego@gnufans.org> writes:
> hello
>
> I can get set-window-vscroll to work from M-: or from inside functions
> containing that one single command.
>
> Example:
>
> (defun vel-scroll-up-fractional (acc)
> (set-window-vscroll nil acc))
>
> works just fine when acc is 0.5
>
> However,
> try
>
> (defun vel-scroll-up (amount acc)
> (scroll-up amount)
> (set-window-vscroll nil acc))
>
> where amount is 0 and acc is 0.5. (the first one is a dummy line
> supposed to do nothing here..)
>
> And the second line seems to have no effect at all.
>
I can confirm this (not) happening here too.
The problem seems to that after a scroll (even a zero scroll), the
function window_scroll_pixel_based sets w->force_start = Qt, which
later causes the redisplay engine to set w->vscroll to 0.
Since this happens during redisplay, the set-window-vscroll
function has already been called, and the explicit setting of
w->vscroll is lost.
The following version is one way to work-around this problem:
(defun vel-scroll-up (amount acc)
(scroll-up amount)
(sit-for 0)
(set-window-vscroll nil acc))
I think the proper fix is to define a separate w->vscroll_extra member
(controlled via set-window-vscroll) which specifies the smooth scroll
offset the user wants ... and let the automatic vscroll adjustment
take this into account (except at the top and bottom of the buffer).
--
Kim F. Storm <storm@cua.dk> http://www.cua.dk
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: set-window-vscroll causes infinite loop in redisplay
2003-02-24 1:31 set-window-vscroll causes infinite loop in redisplay Kim F. Storm
2003-02-24 15:47 ` Kim F. Storm
@ 2003-02-26 9:47 ` Richard Stallman
1 sibling, 0 replies; 5+ messages in thread
From: Richard Stallman @ 2003-02-26 9:47 UTC (permalink / raw)
Cc: emacs-devel
The following patch fixes this. I'll install it tomorrow unless
someone finds a better fix.
I don't see anything obviously wrong with it.
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2003-02-26 9:47 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
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2003-02-24 1:31 set-window-vscroll causes infinite loop in redisplay Kim F. Storm
2003-02-24 15:47 ` Kim F. Storm
2003-02-25 13:34 ` Kim F. Storm
[not found] ` <87u1et7mf2.fsf@computer.localdomain>
2003-02-26 0:20 ` Kim F. Storm
2003-02-26 9:47 ` Richard Stallman
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