Re: mutt/2019: menu_context itches
The following reply was made to PR mutt/2019; it has been noted by GNATS.
From: Thomas Roessler <roessler@xxxxxxxxxxxxxxxxxx>
To: bug-any@xxxxxxxxxxxxx
Cc: Mutt Developers <mutt-dev@xxxxxxxx>
Subject: Re: mutt/2019: menu_context itches
Date: Tue, 1 Nov 2005 09:33:57 +0100
On 2005-10-31 19:55:01 +0100, Alain Bench wrote:
> Your patch fixes the break-dance in said conditions, but
> unfortunately creates other problems in other conditions. Especially
> cursor altitude is no more stable in odd menu height, in all conditions
> $menu_context keeps one less margin below indicator, and scrolling down
> with $menu_context=3D0 overwrites pager status line.
ooops.
> Or same but clearer the
> patch-1.5.11.ab.menu_context_itches_2019.2a (against straight
> 1.5.11) I upload to Gnats. With big $menu_context this should
> always give stable altitude cursor: Centered on an odd height
> menu, and just below center on an even one.
I had missed your patch.
I don't like the explicit special-casing, though... So, why don't
we change the flow of control a little bit, as in the patch below?
(Let me know if I'm missing another corner case with that version. ;-)
--=20
Thomas Roessler =B7 Personal soap box at <http://log.does-not-exist.org/>.
diff -u -r3.22 menu.c
--- menu.c 31 Oct 2005 10:29:45 -0000 3.22
+++ menu.c 1 Nov 2005 08:29:12 -0000
@@ -384,19 +384,32 @@
set_option (OPTNEEDREDRAW);
}
}
- else if (menu->current >=3D menu->top + menu->pagelen - c) /* indicator =
below bottom threshold */
- {
- if (option (OPTMENUSCROLL) || (menu->pagelen <=3D 0))
- menu->top =3D menu->current - menu->pagelen + c;
- else
- menu->top +=3D (menu->pagelen - c) * ((menu->current - menu->top) / =
(menu->pagelen - c)) - c;
- }
- else if (menu->current < menu->top + c) /* indicator above top threshold=
*/
+ else=20
{
- if (option (OPTMENUSCROLL) || (menu->pagelen <=3D 0))
- menu->top =3D menu->current - c;
- else
- menu->top -=3D (menu->pagelen - c) * ((menu->top + menu->pagelen - 1=
- menu->current) / (menu->pagelen - c)) - c;
+ /*=20
+ * If c =3D menu->pagelen / 2 and menu->pagelen is even, then (obvious=
ly):
+ *=20
+ * menu->top + menu->pagelen - c =3D=3D menu->top + c
+ *
+ * In that case, having an "else if" below leads to what has become kn=
own as the
+ * indicator break dance effect. Instead of special-casing, we just f=
orget the=20
+ * "else".
+ */
+ =20
+ if (menu->current < menu->top + c) /* indicator above top threshold */
+ {
+ if (option (OPTMENUSCROLL) || (menu->pagelen <=3D 0))
+ menu->top =3D menu->current - c;
+ else
+ menu->top -=3D (menu->pagelen - c) * ((menu->top + menu->pagelen - 1 -
me=
nu->current) / (menu->pagelen - c)) - c;
+ }
+ if (menu->current >=3D menu->top + menu->pagelen - c) /* indicator bel=
ow bottom threshold */
+ {
+ if (option (OPTMENUSCROLL) || (menu->pagelen <=3D 0))
+ menu->top =3D menu->current - menu->pagelen + c + 1;
+ else
+ menu->top +=3D (menu->pagelen - c) * ((menu->current - menu->top) /
(menu=
->pagelen - c)) - c;
+ }
}
=20
if (!option (OPTMENUMOVEOFF)) /* make entries stick to bottom */