Re: Apropos emacs-intl-fonts & https://wiki.debian.org/DebianHebrew

[Eli Zaretskii <eliz@gnu.org>]

> From: Jambunathan K <kjambunathan@gmail.com>
> Cc: oub@mat.ucm.es,  emacs-devel@gnu.org
> Date: Mon, 04 Nov 2013 00:21:00 +0530
> 
> What I see differs from what Uwe said he wanted.  See the attached
> screenshots.  The "other" screenshot is from LibreOffice.  I cannot read
> Hebrew so I have no idea what is Hello or what is David.

Then I guess you want this:

| שלום       | דוד  ‏ |
| Hello      | ‏David |

It doesn't really matter, the solution (one of them) was demonstrated
by my previous example as well.

> I am just trying to get a quick help on Bidi.  I am trying to figure out
> what markers would be needed to achieve the rendering in Emacs.  I can
> use that as a baseline to form a basic understanding of Bidi.

If you really want basic understanding of bidi, you will need to read
the UAX#9, the annex to the Unicode standard that describes the
Unicode Bidirectional Algorithm.  That is what Emacs implements.

But IMO, that's overkill.  The node in the ELisp manual that I pointed
to includes a cookbook that you should be able to use to get this
stuff right, without understanding too much how it works internally.

> Is there a Bidirectional mode (think Whitespace mode) whereby I can get
> a visual feedback on the markers used in the text?

Not sure what you mean.  The bidirectional control characters by
default are visible (as thin spaces), and you can type "C-x =" on them
(or "C-u C-x =", if you want more details) to see which one is which.
Alternatively, you can customize glyphless-char-display-control to
display these characters as boxes with the Unicode codepoint spelled
out inside.

So the visual feedback is immediate without any special modes.  But
I'm not sure how this will help you: the effect of these marks on the
surrounding text is complex and cannot be predicted without a deep
understanding of the reordering algorithm.  You are welcome to study
it, but that is not needed just to solve your immediate problems.

> (I have consulted the Info node briefly. May be multiple readings would
> be required to form a good understanding.)

The manual gives precise instructions how to use each method, just try
them one by one and see which one fits best.