From: Keith David Bershatsky <esq@lawlist.com>
To: Eli Zaretskii <eliz@gnu.org>
Cc: emacs-devel@gnu.org
Subject: Re: Problems with move_it_in_display_line_to X when tabs exist.
Date: Sun, 14 Jan 2018 21:48:12 -0800 [thread overview]
Message-ID: <m2k1wjk6zn.wl%esq@lawlist.com> (raw)
I am still working on troubleshooting how the value of it->pixel_width is determined. In the current fact pattern, I am using the following settings:
(setq display-line-numbers t)
(setq buffer-display-table (make-display-table))
(aset buffer-display-table
?\t
(vector (make-glyph-code ?\u00BB 'font-lock-warning-face)
(make-glyph-code ?\t 'highlight)))
(setq tab-width 8)
I am placing a tab at flush-left and some text following the tab, such as:
Hello-world.
I am calling interactively (scroll-left 1) to temporarily scroll the text to the left 1 column at a time.
I believe that x_produce_glyphs sets the it->pixel-width of the stretch tab incorrectly (while scrolling 2 or more columns to the left), which affects the ability to properly move by it.pixel_width when calling move_it_in_display_line_to. As far as I can tell, this problem _only_ happens when displaying native line numbers.
The problem likely begins at line 28228 of xdisp.c where we have a comment:
/* i.e. (it->char_to_display == '\t') */
I am trying to understand that section of code.
QUESTION: Is this line of code:
int next_tab_x = ((1 + x + tab_width - 1) / tab_width) * tab_width;
the same thing as:
int next_tab_x = x + tab_width;
If we add 1 and then subtract 1, we did not do anything meaningful.
If we divide something by tab_width and then multiply it by tab_width, then we are back again at where we started.
EXAMPLE #1: (1 + 11 + 77 - 1) / 77) * 77 = 88
EXAMPLE #2: 11 + 77 = 88
Thanks,
Keith
next reply other threads:[~2018-01-15 5:48 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-15 5:48 Keith David Bershatsky [this message]
2018-01-15 12:06 ` Problems with move_it_in_display_line_to X when tabs exist Eli Zaretskii
-- strict thread matches above, loose matches on Subject: below --
2018-01-23 7:38 Keith David Bershatsky
2018-01-21 20:32 Keith David Bershatsky
2018-01-16 17:53 Keith David Bershatsky
2018-01-16 4:41 Keith David Bershatsky
2018-01-16 17:00 ` Eli Zaretskii
2017-12-06 16:24 Keith David Bershatsky
2017-12-04 8:03 Keith David Bershatsky
2017-12-04 3:01 Keith David Bershatsky
2017-12-04 16:26 ` Eli Zaretskii
2017-12-03 20:56 Keith David Bershatsky
2017-12-04 15:48 ` Eli Zaretskii
2017-12-03 3:38 Keith David Bershatsky
2017-12-03 14:29 ` Eli Zaretskii
2017-12-02 22:28 Keith David Bershatsky
2017-12-03 3:32 ` Eli Zaretskii
2017-12-02 19:52 Keith David Bershatsky
2017-12-02 21:14 ` Eli Zaretskii
2017-11-30 4:29 Keith David Bershatsky
2017-11-29 6:12 Keith David Bershatsky
2017-11-29 18:04 ` Eli Zaretskii
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