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: Sun, 22 Jan 2017 12:21:20 -0500 [thread overview]
Message-ID: <87inp7ui27.fsf@users.sourceforge.net> (raw)
In-Reply-To: <83d1fg5iku.fsf@gnu.org> (Eli Zaretskii's message of "Sat, 21 Jan 2017 21:17:05 +0200")
npostavs@users.sourceforge.net writes:
>
> I came up with this; it works
Actually, that doesn't work, I must have not compiled before testing.
Eli Zaretskii <eliz@gnu.org> writes:
>>
>> I'm not entirely clear why there is a branch in that code.
>
> Because of line-spacing, perhaps? Did you test your code when
> line-spacing is at non-default value? In general, it is safer to go
> to the next screen line than reason about where it will start.
>
>> +int
>> +partial_line_height (const struct it *it_origin)
>> +{
>> + struct it it = *it_origin;
>
> When you copy the iterator structure and modify the copy, you need to
> save and restore the bidi cache, using SAVE_IT and RESTORE_IT macros.
> Otherwise, the code which calls this function will work incorrectly if
> it uses the original iterator after the call, because the bidi cache
> is not restored to its state before the call.
I came up with this modified version of partial_line_height, which does
actually work. Having to do RESTORE_IT (&it, &it, it_data) is a bit
unintuitive though. I don't understand what the typical use case of
this macro is, if it's going to copy back the new state into the
original `it', then why use a separate `it' in the first place?
By the way, while testing I noticed that `set-window-text-height'
doesn't take `line-spacing' into account, should it?
int
partial_line_height (struct it *it_origin)
{
int partial_height;
void *it_data = NULL;
struct it it;
SAVE_IT (it, *it_origin, it_data);
move_it_to (&it, ZV, -1, it.last_visible_y, -1,
MOVE_TO_POS | MOVE_TO_Y);
if (it.what == IT_EOB)
{
int vis_height = it.last_visible_y - it.current_y;
int height = it.ascent + it.descent;
partial_height = (vis_height < height) ? vis_height : 0;
}
else
{
int last_line_y = it.current_y;
move_it_by_lines (&it, 1);
partial_height = (it.current_y > it.last_visible_y)
? it.last_visible_y - last_line_y : 0;
}
RESTORE_IT (&it, &it, it_data);
return partial_height;
}
next prev parent reply other threads:[~2017-01-22 17:21 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
2017-01-21 19:17 ` Eli Zaretskii
2017-01-22 17:21 ` npostavs [this message]
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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