From: npostavs@users.sourceforge.net
To: Eli Zaretskii <eliz@gnu.org>
Cc: ahyatt@gmail.com, 5718@debbugs.gnu.org, gavenkoa@gmail.com
Subject: bug#5718: scroll-margin in buffer with small line count.
Date: Sat, 21 Jan 2017 13:46:37 -0500 [thread overview]
Message-ID: <87pojguu7m.fsf@users.sourceforge.net> (raw)
In-Reply-To: <83a8ar9bl6.fsf@gnu.org> (Eli Zaretskii's message of "Mon, 16 Jan 2017 19:08:37 +0200")
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Eli Zaretskii <eliz@gnu.org> writes:
>
> There's already such a calculation in window_scroll_pixel_based:
>
> /* See if point is on a partially visible line at the end. */
> if (it.what == IT_EOB)
> partial_p = it.current_y + it.ascent + it.descent > it.last_visible_y;
> else
> {
> move_it_by_lines (&it, 1);
> partial_p = it.current_y > it.last_visible_y;
> }
>
> (This is preceded by moving the iterator to the point's screen line or
> to EOB, whichever comes first.) The value it.current_y is the Y
> coordinate of the top edge of a glyph row (the value is zero for the
> first screen line), so if it.last_visible_y is farther away from that
> than the height of the glyph row, that glyph row is fully visible;
> otherwise it isn't.
I'm not entirely clear why there is a branch in that code. I came up
with this; it works, though I'm not sure if it's the best way:
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From 6944c7badade2477f381acf3b0922e5309e063d8 Mon Sep 17 00:00:00 2001
From: Noam Postavsky <npostavs@gmail.com>
Date: Sat, 21 Jan 2017 13:24:47 -0500
Subject: [PATCH v3] Fix scrolling with partial lines
* src/xdisp.c (partial_line_height): New function.
(try_scrolling):
* src/window.c (window_scroll_pixel_based): Use it for calculating the
pixel scroll margin correctly in a window with partial lines.
---
src/dispextern.h | 1 +
src/window.c | 2 +-
src/xdisp.c | 14 +++++++++++++-
3 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/src/dispextern.h b/src/dispextern.h
index 51222e6..470330a 100644
--- a/src/dispextern.h
+++ b/src/dispextern.h
@@ -3263,6 +3263,7 @@ void move_it_past_eol (struct it *);
void move_it_in_display_line (struct it *it,
ptrdiff_t to_charpos, int to_x,
enum move_operation_enum op);
+int partial_line_height (const struct it *it_origin);
bool in_display_vector_p (struct it *);
int frame_mode_line_height (struct frame *);
extern bool redisplaying_p;
diff --git a/src/window.c b/src/window.c
index f664597..300472e 100644
--- a/src/window.c
+++ b/src/window.c
@@ -5148,7 +5148,7 @@ window_scroll_pixel_based (Lisp_Object window, int n, bool whole, bool noerror)
in the scroll margin at the bottom. */
move_it_to (&it, PT, -1,
(it.last_visible_y - WINDOW_HEADER_LINE_HEIGHT (w)
- - this_scroll_margin - 1),
+ - partial_line_height (&it)- this_scroll_margin - 1),
-1,
MOVE_TO_POS | MOVE_TO_Y);
diff --git a/src/xdisp.c b/src/xdisp.c
index 55bb34a..9dc65b8 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -9859,6 +9859,17 @@ move_it_by_lines (struct it *it, ptrdiff_t dvpos)
}
}
+int
+partial_line_height (const struct it *it_origin)
+{
+ struct it it = *it_origin;
+ move_it_to (&it, ZV, -1, it.last_visible_y, -1,
+ MOVE_TO_POS | MOVE_TO_Y);
+ int vis_height = it.last_visible_y - it.current_y;
+ int log_height = it.ascent + it.descent;
+ return max (0, log_height - vis_height);
+}
+
/* Return true if IT points into the middle of a display vector. */
bool
@@ -15368,7 +15379,8 @@ try_scrolling (Lisp_Object window, bool just_this_one_p,
/* Compute the pixel ypos of the scroll margin, then move IT to
either that ypos or PT, whichever comes first. */
start_display (&it, w, startp);
- scroll_margin_y = it.last_visible_y - this_scroll_margin
+ scroll_margin_y = it.last_visible_y - partial_line_height (&it)
+ - this_scroll_margin
- frame_line_height * extra_scroll_margin_lines;
move_it_to (&it, PT, -1, scroll_margin_y - 1, -1,
(MOVE_TO_POS | MOVE_TO_Y));
--
2.9.3
next prev parent reply other threads:[~2017-01-21 18:46 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-14 17:26 bug#5718: scroll-margin in buffer with small line count Oleksandr Gavenko
2016-08-11 4:11 ` Andrew Hyatt
2016-08-11 12:03 ` npostavs
2016-08-11 13:05 ` Oleksandr Gavenko
2016-08-11 13:24 ` Noam Postavsky
2016-08-12 7:54 ` Oleksandr Gavenko
2016-08-11 15:28 ` Eli Zaretskii
2016-08-13 22:01 ` npostavs
2016-08-14 2:36 ` Eli Zaretskii
2016-09-11 20:58 ` npostavs
2016-09-12 6:19 ` martin rudalics
2016-09-14 2:23 ` npostavs
2016-09-14 5:30 ` martin rudalics
2016-09-12 17:36 ` Eli Zaretskii
2016-09-14 2:40 ` npostavs
2016-09-14 17:26 ` Eli Zaretskii
2017-01-03 0:48 ` npostavs
2017-01-07 8:17 ` Eli Zaretskii
2017-01-14 4:18 ` npostavs
2017-01-14 7:58 ` Eli Zaretskii
2017-01-15 21:43 ` npostavs
2017-01-16 17:08 ` Eli Zaretskii
2017-01-21 18:46 ` npostavs [this message]
2017-01-21 19:17 ` Eli Zaretskii
2017-01-22 17:21 ` npostavs
2017-01-22 17:58 ` Eli Zaretskii
2017-01-29 0:57 ` npostavs
2017-01-30 15:29 ` Eli Zaretskii
2017-01-31 4:52 ` npostavs
2017-01-31 15:33 ` Eli Zaretskii
2017-02-03 2:40 ` npostavs
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