Re: char-displayable-p returns t for undisplayable characters

[Kenichi Handa]

In article <address@hidden>, Jonathan Yavner <address@hidden> (by way of 
Jonathan Yavner        <address@hidden>) writes:
> The output is reasonable: 351 for iso88591 mode, 303 251 for utf8.  The docs
> for xterm do not specify how to change the locale; presumably changing LANG
> isn't enough, so I'm getting a blank because Emacs is sending Latin-1 but
> xterm is still expecting UTF-8.

But, you wrote:

> Note: xterm in locale iso88591 *can* display an e-acute, but not when running
> Emacs.  Why?

How did you see e-acute on xterm?

Anyway, locale should be changed before you invoke xterm (or
any other X client).  If you are using Emacs under a locale
different from what xterm thinks, you must adjust Emacs
manually by C-x RET l.   In the above case, C-x RET l utf-8 RET.

JY>  Under X11, the e-acute and ellipsis characters both display properly in
JY>  Emacs, while '√' (square root) displays as a white rectangle.

KH>  Please tell me the result of the followings:
KH>  (fontset-font (frame-parameter nil 'font) ?√)
>   nil
KH>  (fontset-font "fontset-default" ?√)
>   (nil . "iso10646-1")
KH>  And please type C-u C-x = while putting cursor on √.
>   character: √ (01236072, 343098, 0x53c3a, U+221A)
>     charset: mule-unicode-0100-24ff
>            (Unicode characters of the range U+0100..U+24FF.)
>  code point: 120 58
>      syntax: w        which means: word
> buffer code: 0x9C 0xF4 0xF8 0xBA
>   file code: 0xE2 0x88 0x9A (encoded by coding system mule-utf-8)
>     display: by this font (glyph code)
>      -Adobe-Courier-Medium-R-Normal--14-140-75-75-M-90-ISO10646-1 (0x221A)

So, this abobe font doesn't contain a glyph for square.
Currently Emacs can't detect if an iso10646-1 fonts surely
contains specific glyph or not.

> -----------------------------------------------------------------------------
> ---------------- Actually, the above is for U+221A "SQUARE ROOT".  If I
>  cut-and-paste from your

> email, I get a square root character that Emacs does display:
>>  (fontset-font (frame-parameter nil 'font) ?√)

>   nil

>>  (fontset-font "fontset-default" ?√)

>   (nil . "jisx0208.1990")

Ah, it seems that the square root is encoded into the
charset japanese-jisx0208 (not unicode) in the previous
mail.

---
Ken'ichi HANDA
address@hidden