From: Keith David Bershatsky <esq@lawlist.com>
To: Eli Zaretskii <eliz@gnu.org>
Cc: 29002@debbugs.gnu.org
Subject: bug#29002: it.first_visible_x is erroneously 0 while horizontal scrolling.
Date: Sun, 29 Oct 2017 10:29:29 -0700 [thread overview]
Message-ID: <m2k1zd6ex2.wl%esq@lawlist.com> (raw)
In-Reply-To: <m2h8umbu0k.wl%esq@lawlist.com>
Here is a link to screen-shot #3:
https://www.lawlist.com/images/bug_hscl_03.png
In that screen-shot, we make the following observations:
* A total of 5 screen lines.
* Line 1 is the current line.
* All 5 lines visually appear to be horizontally scrolled.
* Using the revised function bug-hscroll (below), we iterate over each screen line and generate the values for it.first_visible_x and it.vpos.
* it.first_visible_x returns as being 0 for each of the 5 screen lines.
It is as though Emacs is unaware that the non-current lines still visually appear to be hscrolled, because Emacs "thinks" they are not.
DEFUN ("bug-hscroll", Fbug_hscroll, Sbug_hscroll, 0, 0, 0,
doc: /* Demonstrate the Emacs hscroll bug. */)
(void)
{
struct window *w = decode_live_window (selected_window);
struct it it;
void *itdata = bidi_shelve_cache ();
struct text_pos start_text_position;
Lisp_Object temp = Qnil;
Lisp_Object result = Qnil;
Vmax_mini_window_height = make_number (1);
SET_TEXT_POS_FROM_MARKER (start_text_position, w->start);
start_display (&it, w, start_text_position);
while (true)
{
temp = listn (CONSTYPE_HEAP, 3,
make_number (it.vpos),
build_string (" | "),
make_number (it.first_visible_x));
result = Fcons (temp, result);
if (IT_CHARPOS (it) == ZV)
break;
move_it_by_lines (&it, 1);
if (it.current_y >= it.last_visible_y)
break;
}
bidi_unshelve_cache (itdata, false);
result = Fnreverse (result);
AUTO_STRING (my_string_one, "%s");
CALLN (Fmessage, my_string_one, result);
return result;
}
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
DATE: [10-29-2017 04:23:07] <29 Oct 2017 13:23:07 +0200>
FROM: Eli Zaretskii <eliz@gnu.org>
>
> > Date: Thu, 26 Oct 2017 11:56:08 -0700
> > From: Keith David Bershatsky <esq@lawlist.com>
> > Cc: 29002@debbugs.gnu.org
> >
> > Unfortunately, w->min_hscroll returns a value of 0 in this example.
>
> For the lines other than the current one, you should use
> it.first_visible_x, it is simpler. For the current line, use
> w->hscroll.
next prev parent reply other threads:[~2017-10-29 17:29 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-26 1:03 bug#29002: it.first_visible_x is erroneously 0 while horizontal scrolling Keith David Bershatsky
2017-10-26 3:45 ` Keith David Bershatsky
2017-10-26 4:51 ` Eli Zaretskii
2017-10-26 6:20 ` Keith David Bershatsky
2017-10-26 15:56 ` Eli Zaretskii
2017-10-26 18:56 ` Keith David Bershatsky
2017-10-29 11:23 ` Eli Zaretskii
2017-10-29 17:29 ` Keith David Bershatsky [this message]
2017-10-29 18:29 ` Eli Zaretskii
2017-10-29 18:56 ` Eli Zaretskii
2017-10-29 18:56 ` Keith David Bershatsky
2017-10-29 19:23 ` Eli Zaretskii
2017-10-29 19:08 ` Keith David Bershatsky
2017-10-29 20:12 ` Keith David Bershatsky
2017-10-30 18:02 ` Eli Zaretskii
2017-10-30 19:36 ` Keith David Bershatsky
2017-11-04 9:32 ` Eli Zaretskii
2017-11-05 0:16 ` Keith David Bershatsky
2017-11-05 9:15 ` Keith David Bershatsky
2017-11-05 10:44 ` Eli Zaretskii
2017-11-05 16:59 ` Keith David Bershatsky
2017-11-05 18:12 ` Eli Zaretskii
2017-11-06 1:05 ` Keith David Bershatsky
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