Re: bidi and shaping problems in describe-input-method

[Kenichi Handa <handa@m17n.org>]

In article <83399i149j.fsf@gnu.org>, Eli Zaretskii <eliz@gnu.org> writes:
>   (insert (char-code-property-description 'decomposition '(#x64C)))

> Somehow, using this produces a correct display of the character
> (albeit enclosed in quotes) without any problems.  Perhaps Handa-san
> could explain what kind of magic the above does, as compared to simply
> inserting the same character into the buffer.  The only sign of magic
> I see is this:

>   (char-code-property-description 'decomposition '(#x64C))

>>> #("'ٌ'" 1 2 (composition ((1 . "	ٌ	"))))

Yes, that function inserts a static composition that uses
this magic (excerpt from the docstring of compose-region):

------------------------------------------------------------
If it is a string, the elements are alternate characters.  In
this case, TAB element has a special meaning.  If the first
character is TAB, the glyphs are displayed with left padding space
so that no pixel overlaps with the previous column.  If the last
character is TAB, the glyphs are displayed with right padding
space so that no pixel overlaps with the following column.
------------------------------------------------------------

And if there's a static composition, the automatic (dynamic)
composition is surpressed.

> Anyway, maybe we could use something like this in generating the
> keyboard layouts by quail.el.

I agree.  I'll commit a proper fix soon.

---
Kenichi Handa
handa@m17n.org