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Fix bug #12811 with scrolling under scroll-up/down-aggressively.

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src/xdisp.c (try_scrolling): Fix correction of aggressive-scroll
 amount when the scroll margins are too large.  When scrolling
 backwards in the buffer, give up if cannot reach point or the
 scroll margin within a reasonable number of screen lines.  Fixes
 point position in window under scroll-up/down-aggressively when
 point is positioned many lines beyond the window top/bottom.
This commit is contained in:
Eli Zaretskii 2012-11-06 18:36:02 +02:00
parent 072c7b659c
commit acf93bcf19
2 changed files with 34 additions and 16 deletions
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10
src/ChangeLog
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@ -1,3 +1,13 @@
2012-11-06 Eli Zaretskii <eliz@gnu.org>
* xdisp.c (try_scrolling): Fix correction of aggressive-scroll
amount when the scroll margins are too large. When scrolling
backwards in the buffer, give up if cannot reach point or the
scroll margin within a reasonable number of screen lines. Fixes
point position in window under scroll-up/down-aggressively when
point is positioned many lines beyond the window top/bottom.
(Bug#12811)
2012-11-05 Eli Zaretskii <eliz@gnu.org>
* ralloc.c (relinquish): If real_morecore fails to return memory

40
src/xdisp.c
View file

@ -14791,13 +14791,18 @@ try_scrolling (Lisp_Object window, int just_this_one_p,
if (NUMBERP (aggressive))
{
double float_amount = XFLOATINT (aggressive) * height;
amount_to_scroll = float_amount;
if (amount_to_scroll == 0 && float_amount > 0)
amount_to_scroll = 1;
int aggressive_scroll = float_amount;
if (aggressive_scroll == 0 && float_amount > 0)
aggressive_scroll = 1;
/* Don't let point enter the scroll margin near top of
the window. */
if (amount_to_scroll > height - 2*this_scroll_margin + dy)
amount_to_scroll = height - 2*this_scroll_margin + dy;
the window. This could happen if the value of
scroll_up_aggressively is too large and there are
non-zero margins, because scroll_up_aggressively
means put point that fraction of window height
_from_the_bottom_margin_. */
if (aggressive_scroll + 2*this_scroll_margin > height)
aggressive_scroll = height - 2*this_scroll_margin;
amount_to_scroll = dy + aggressive_scroll;
}
}
@ -14857,7 +14862,8 @@ try_scrolling (Lisp_Object window, int just_this_one_p,
/* Compute the vertical distance from PT to the scroll
margin position. Move as far as scroll_max allows, or
one screenful, or 10 screen lines, whichever is largest.
Give up if distance is greater than scroll_max. */
Give up if distance is greater than scroll_max or if we
didn't reach the scroll margin position. */
SET_TEXT_POS (pos, PT, PT_BYTE);
start_display (&it, w, pos);
y0 = it.current_y;
@ -14867,7 +14873,8 @@ try_scrolling (Lisp_Object window, int just_this_one_p,
y_to_move, -1,
MOVE_TO_POS | MOVE_TO_X | MOVE_TO_Y);
dy = it.current_y - y0;
if (dy > scroll_max)
if (dy > scroll_max
|| IT_CHARPOS (it) < CHARPOS (scroll_margin_pos))
return SCROLLING_FAILED;
/* Compute new window start. */
@ -14885,15 +14892,16 @@ try_scrolling (Lisp_Object window, int just_this_one_p,
if (NUMBERP (aggressive))
{
double float_amount = XFLOATINT (aggressive) * height;
amount_to_scroll = float_amount;
if (amount_to_scroll == 0 && float_amount > 0)
amount_to_scroll = 1;
amount_to_scroll -=
this_scroll_margin - dy - FRAME_LINE_HEIGHT (f);
int aggressive_scroll = float_amount;
if (aggressive_scroll == 0 && float_amount > 0)
aggressive_scroll = 1;
/* Don't let point enter the scroll margin near
bottom of the window. */
if (amount_to_scroll > height - 2*this_scroll_margin + dy)
amount_to_scroll = height - 2*this_scroll_margin + dy;
bottom of the window, if the value of
scroll_down_aggressively happens to be too
large. */
if (aggressive_scroll + 2*this_scroll_margin > height)
aggressive_scroll = height - 2*this_scroll_margin;
amount_to_scroll = dy + aggressive_scroll;
}
}