From: Eli Zaretskii <eliz@gnu.org>
To: Yuan Fu <casouri@gmail.com>
Cc: larsi@gnus.org, emacs-devel@gnu.org
Subject: Re: Line wrap reconsidered
Date: Sat, 30 May 2020 09:14:56 +0300 [thread overview]
Message-ID: <83blm6lzj3.fsf@gnu.org> (raw)
In-Reply-To: <BFCA1242-EA8C-4C1A-85CF-DD9E7A3E5FE1@gmail.com> (message from Yuan Fu on Fri, 29 May 2020 17:20:21 -0400)
> From: Yuan Fu <casouri@gmail.com>
> Date: Fri, 29 May 2020 17:20:21 -0400
> Cc: Lars Ingebrigtsen <larsi@gnus.org>,
> emacs-devel@gnu.org
>
> > Then you'll need to augment the test
> >
> > else if (may_wrap)
> >
> > with a test that the current character can be at BOL. Maybe you
> > should also make may_wrap a tristate instead of just a boolean YES/NO.
> >
>
> I think I did jus that, i.e., if (may_wrap && char_can_wrap_before(it)).
Fundamentally, yes. But having a complex condition
if (FOO && BAR)
makes the code harder to read and understand, and thus makes logical
errors easier, than a simple condition like
if (FOOBAR == some_value)
> >> Essentially I want to ask “if may_wrap == true, what does that mean? (In bidi context)” Did the character to the left of me (on glass) set it or the character to the right of me set it?
> >
> > The one to the left. But it is not necessarily the "previous"
> > character in buffer position order.
>
> I see, but then I don’t don’t understand how does the current code work with bidi display. In bidi context, space char can’t appear on the right of the line, which is the beginning of a logic line, right? That requires the logic to reverse. Is there something I’m missing?
I think the cause of the confusion is the "in bidi context" part.
There are two such "contexts", and they behave differently:
. RTL characters when bidi-paragraph-direction is left-to-right
. RTL characters when bidi-paragraph-direction is right-to-left
Which one were you talking about? I was talking about the first one.
> Since may_wrap’s meaning is in terms of left and right, it need to be reversed in bidi text, no?
If bidi-paragraph-direction is right-to-left, then yes, they are
reversed. But not if the paragraph direction is left-to-right.
> One more question. If I type 123456789... and set bidi-paragraph-direction to ‘right-to-left, it is still 123456789…, just aligned to the right. I expected to see …987654321, that’s what right-to-left mean in Chinese text. Why the order of each character not revered?
Digits and LTR characters (like English text) are rendered
left-to-right even in RTL paragraphs, so what you see is correct.
That's why this is called "bidirectional": the direction is not just
universally right-to-left.
> UAX#9 didn’t say anything helpful.
It does, albeit in a convoluted and hard-to-grasp way. See paragraph
3.3.6 there, and then rule L2 in paragraph 3.4, which describes the
reordering procedure.
next prev parent reply other threads:[~2020-05-30 6:14 UTC|newest]
Thread overview: 88+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-25 18:13 Line wrap reconsidered Yuan Fu
2020-05-25 19:23 ` Eli Zaretskii
2020-05-25 19:31 ` Yuan Fu
2020-05-26 1:55 ` Ihor Radchenko
2020-05-26 12:55 ` Joost Kremers
2020-05-26 13:35 ` Yuan Fu
2020-05-26 14:47 ` Eli Zaretskii
2020-05-26 15:01 ` Ihor Radchenko
2020-05-26 15:29 ` Eli Zaretskii
2020-05-26 15:46 ` Ihor Radchenko
2020-05-26 16:29 ` Eli Zaretskii
2020-05-26 15:59 ` Stefan Monnier
2020-05-26 16:31 ` Eli Zaretskii
2020-05-26 16:43 ` Yuan Fu
2020-05-26 16:43 ` Ihor Radchenko
2020-05-26 18:57 ` Eli Zaretskii
2020-05-26 19:10 ` Yuan Fu
2020-05-26 19:59 ` Eli Zaretskii
2020-05-26 19:12 ` Ihor Radchenko
2020-05-26 20:04 ` Eli Zaretskii
2020-05-26 21:01 ` Stefan Monnier
2020-05-25 19:31 ` Stefan Monnier
2020-05-25 19:51 ` Yuan Fu
2020-05-25 20:43 ` Lars Ingebrigtsen
2020-05-25 23:26 ` Yuan Fu
2020-05-25 23:32 ` Yuan Fu
2020-05-26 2:15 ` Yuan Fu
2020-05-26 3:30 ` Yuan Fu
2020-05-26 4:46 ` Yuan Fu
2020-05-26 15:14 ` Eli Zaretskii
2020-05-26 15:00 ` Eli Zaretskii
2020-05-26 14:54 ` Eli Zaretskii
2020-05-26 17:34 ` Yuan Fu
2020-05-26 19:50 ` Eli Zaretskii
2020-05-26 20:31 ` Yuan Fu
2020-05-26 22:29 ` Yuan Fu
2020-05-27 17:29 ` Eli Zaretskii
2020-05-28 17:31 ` Yuan Fu
2020-05-28 18:05 ` Eli Zaretskii
2020-05-28 19:34 ` Yuan Fu
2020-05-28 20:42 ` Yuan Fu
2020-05-29 7:17 ` Eli Zaretskii
2020-05-29 6:56 ` Eli Zaretskii
2020-05-29 21:20 ` Yuan Fu
2020-05-30 6:14 ` Eli Zaretskii [this message]
2020-05-31 17:39 ` Yuan Fu
2020-05-31 17:55 ` Eli Zaretskii
2020-05-31 18:23 ` Yuan Fu
2020-05-31 18:47 ` Eli Zaretskii
2020-06-18 21:46 ` Yuan Fu
2020-06-19 6:17 ` Eli Zaretskii
2020-06-19 12:04 ` Yuan Fu
2020-06-19 12:38 ` Eli Zaretskii
2020-06-19 17:22 ` Yuan Fu
2020-06-19 17:47 ` Eli Zaretskii
2020-06-19 18:03 ` Yuan Fu
2020-06-19 18:34 ` Eli Zaretskii
2020-07-12 17:25 ` Yuan Fu
2020-07-12 18:27 ` Eli Zaretskii
2020-07-12 19:28 ` Yuan Fu
2020-07-13 19:46 ` Yuan Fu
2020-07-18 8:15 ` Eli Zaretskii
2020-07-18 17:14 ` Yuan Fu
2020-07-18 19:49 ` Yuan Fu
2020-07-18 20:25 ` Stefan Monnier
2020-07-19 14:52 ` Eli Zaretskii
2020-07-19 16:16 ` Yuan Fu
2020-07-19 16:17 ` Yuan Fu
2020-08-13 19:35 ` Yuan Fu
2020-08-14 5:55 ` Eli Zaretskii
2020-08-14 15:08 ` Yuan Fu
2020-08-15 9:10 ` Eli Zaretskii
2020-08-15 13:10 ` Fu Yuan
2020-08-15 14:56 ` Eli Zaretskii
2020-08-15 17:34 ` Yuan Fu
2020-08-15 17:46 ` Eli Zaretskii
2020-08-15 18:00 ` Yuan Fu
2020-08-15 18:47 ` Eli Zaretskii
2020-08-16 3:22 ` Yuan Fu
2020-08-16 14:15 ` Eli Zaretskii
2020-08-16 17:31 ` Yuan Fu
2020-08-22 7:42 ` Eli Zaretskii
2020-08-22 20:58 ` Yuan Fu
2020-08-23 7:12 ` Eli Zaretskii
2020-08-24 14:00 ` Yuan Fu
2020-05-27 15:20 ` Eli Zaretskii
2020-05-26 8:02 ` martin rudalics
2020-05-26 12:38 ` Yuan Fu
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