bug#24699: Some characters should have char-width of 2

[Georges Ko <gko@gko.net>]

Eli Zaretskii <eliz@gnu.org> writes:

> Not all characters of a code block have the same width attribute.

OK, understood. I'll use EastAsianWidth.txt as reference.

>> (char-width ?🍁) => 2
>> (char-width ?🐻) => 1
>
> Yes, the 1F400..1F43E range was missing.  I now fixed that on the
> emacs-25 branch, so both of the above expressions return 2.

OK.

>> Could the EastAsianWidth.txt (not found in Emacs sources) used to
>> generate was an old version?
>
> It's more probable that this range was simply omitted.

>> Is the generated output in characters.el starting from this line?
>
> It's not aut-generated, it was written by hand.

Shouldn't all current char-width be checked against EastAsianWidth.txt?
I'll check for discrepancies...

>> A side effect of having non-consistent char-width is badly aligned
>> org-mode tables. A table with a MAPLE LEAF (width=2) and a BEAR FACE
>> (width=1) is aligned like this by org-mode:
>
> The width attribute will only help in alignment of text if the font
> used for these characters is monospaced, and then if the font
> designers indeed kept the width according to Unicode.  Most fonts that
> support these characters are variable-pitch fonts, so you won't have
> any alignment anyway, unless org-table aligns columns on the pixel
> level, by using the pixel size of the text.
>
>> E | W | Char  | Code Point       | Name
>> --+---+-------+------------------+-------------------------------
>> 2 | 1 | 🐀    | #x1F400 (128000) | RAT
>> 2 | 1 | 🐁    | #x1F401 (128001) | MOUSE
>> 2 | 1 | 🐂    | #x1F402 (128002) | OX
>
> On my display, these columns are not aligned at all, even for
> characters whose char-width is 2.  And I don't expect them to be
> aligned, because the font used is Symbola, which is not monospaced.

Segoe UI Symbol seems better in this regard, unfortunately, it has less
displayable characters.

> OK to close this bug now?

OK.

Georges
-- 
 Georges Ko                     gko@gko.net                      2016-10-16