State of Unicode display support on Windows

State of Unicode display support on Windows

[Óscar Fuentes]

Some characters display fine on GNU/Linux but not on Windows. An example
is FISHEYE (?\u25c9) with the Consolas font. Apparently, that font does
not include that character. In GNU/Linux Emacs simply uses DejaVu for
displaying the character, but not on Windows, where a white space is
displayed (the Windows machine also has DejaVu installed.)

Is this a known limitation or a bug?

This is the output of M-x describe-char on Windows XP:

        character: ◉ (9673, #o22711, #x25c9)
preferred charset: unicode (Unicode (ISO10646))
       code point: 0x25C9
           syntax: w 	which means: word
         category: .:Base, j:Japanese
      buffer code: #xE2 #x97 #x89
        file code: #xE2 #x97 #x89 (encoded by coding system utf-8-dos)
          display: by this font (glyph code)
    uniscribe:-outline-Consolas-normal-normal-normal-mono-20-*-*-*-c-*-iso10646-1 (#x03)

Character code properties: customize what to show
  name: FISHEYE
  general-category: So (Symbol, Other)

Re: State of Unicode display support on Windows

[Jason Rumney]

On 12/10/2010 01:33, Óscar Fuentes wrote:
> Some characters display fine on GNU/Linux but not on Windows. An example
> is FISHEYE (?\u25c9) with the Consolas font. Apparently, that font does
> not include that character. In GNU/Linux Emacs simply uses DejaVu for
> displaying the character, but not on Windows, where a white space is
> displayed (the Windows machine also has DejaVu installed.)
>
> Is this a known limitation or a bug?
>
>      uniscribe:-outline-Consolas-normal-normal-normal-mono-20-*-*-*-c-*-iso10646-1 (#x03)
>    

The font is claiming to have that character in position 3 in the glyph 
table. I've also seen the same thing with fonts claiming position 1.  
There is nothing in the documentation for opentype or the font related 
Windows API functions that suggests that there is anything special about 
those glyph indexes, or that it is safe to assume that they mean a 
character is missing from the font.  Currently I think we only treat a 
return of 0 as indicating that the character is missing, as that is 
reserved by the truetype and opentype specs for the character ".notdef".

Re: State of Unicode display support on Windows

[Juanma Barranquero]

On Mon, Oct 11, 2010 at 20:22, Jason Rumney <jasonr@gnu.org> wrote:

> The font is claiming to have that character in position 3 in the glyph
> table.

Which version of DejaVu?

I see the character just fine, and describe-char says:

        character: ◉ (9673, #o22711, #x25c9)
preferred charset: unicode-bmp (Unicode Basic Multilingual Plane
(U+0000..U+FFFF))
       code point: 0x25C9
           syntax: w 	which means: word
         category: .:Base, j:Japanese
      buffer code: #xE2 #x97 #x89
        file code: #xE2 #x97 #x89 (encoded by coding system utf-8-dos)
          display: by this font (glyph code)
    uniscribe:-outline-DejaVu Sans
Mono-normal-normal-normal-mono-13-*-*-*-c-*-iso10646-1 (#x989)

Character code properties: customize what to show
  name: FISHEYE
  general-category: So (Symbol, Other)
  canonical-combining-class: 0 (Spacing, split, enclosing, reordrant,
and Tibetan subjoined)
  bidi-class: ON (Other Neutrals)
  mirrored: N

There are text properties here:
  fontified            t


    Juanma

Re: State of Unicode display support on Windows

[Óscar Fuentes]

Juanma Barranquero <lekktu@gmail.com> writes:

> On Mon, Oct 11, 2010 at 20:22, Jason Rumney <jasonr@gnu.org> wrote:
>
>> The font is claiming to have that character in position 3 in the glyph
>> table.
>
> Which version of DejaVu?
>
> I see the character just fine, and describe-char says:

The character looks fine with DejaVu. It is displayed as whitespace with
Consolas.

[snip]

Re: State of Unicode display support on Windows

[Juanma Barranquero]

On Mon, Oct 11, 2010 at 21:00, Óscar Fuentes <ofv@wanadoo.es> wrote:

> The character looks fine with DejaVu. It is displayed as whitespace with
> Consolas.

OK, sorry for the noise.

    Juanma

Re: State of Unicode display support on Windows

[Eli Zaretskii]

> From: Juanma Barranquero <lekktu@gmail.com>
> Date: Mon, 11 Oct 2010 20:52:35 +0200
> Cc: emacs-devel@gnu.org
> 
> I see the character just fine

So do I, in Emacs 24 as in Emacs 23.2.

> and describe-char says:
> 
>         character: ◉ (9673, #o22711, #x25c9)
> preferred charset: unicode-bmp (Unicode Basic Multilingual Plane
> (U+0000..U+FFFF))
>        code point: 0x25C9
>            syntax: w 	which means: word
>          category: .:Base, j:Japanese
>       buffer code: #xE2 #x97 #x89
>         file code: #xE2 #x97 #x89 (encoded by coding system utf-8-dos)
>           display: by this font (glyph code)
>     uniscribe:-outline-DejaVu Sans
> Mono-normal-normal-normal-mono-13-*-*-*-c-*-iso10646-1 (#x989)

In my case, Emacs uses this font:

    uniscribe:-outline-Arial Unicode MS-normal-normal-normal-sans-13-*-*-*-p-*-gb2312.1980*-*