[Fonts]blank glyph list in fonts.config

[Jungshik Shin]

Since the release of a new CODE2000 font(by James Kass at
http://home.att.net/~jameskass) with glyphs for Hangul Jamos, I've
been trying to test how it works with various browsers. Mozilla
with direct access to  truetype fonts works fine, but Mozilla
with Xft patch has a problem with U+115F(Hangul leading consonant
filler) and U+1160(Hangul vowel filler). In CODE2000, the former
is a spacing(non-zero width) _blank_ glyph while the latter is a
non-spacing(zero-width/combining) _blank_ glyph. When Mozilla with
Xft patch is used to render http://jshin.net/i18n/korean/fillers.html
(or http://jshin.net/i18n/korean/hunmin.html), U+115F and U+1160 are
rendered with hollow boxes instead of spacing and non-spacing(combining)
blanks seemingly because they're not listed among characters allowed
to have blank glyphs.   It's 'seemingly' because Mozilla with Xft patch
has this problem while 'gedit' doesn't have this problem.
Anyway, adding U+115F and U+1160 to the list in fonts.config
solved the problem.

Two screenshots are put up at

http://linux.mizi.com/~ganadist/filler1.png  (with U+115F/U+1160 added
 to blank glyph list)
http://linux.mizi.com/~ganadist/filler2.png  (without )

Mozilla for MS-Windows has a similar problem and I came up with
a similar fix that works. See
.

I'm not sure adding U+115F/U+1160 to the blank glyph list is the best
way, but it works. Keith, could you consider this?

Thank you,

Jungshik

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Re: [Fonts]blank glyph list in fonts.config

[Jungshik Shin]

On Sat, 7 Sep 2002, Keith Packard wrote:

> Around 9 o'clock on Sep 7, Jungshik Shin wrote:
>
> > I'm not sure adding U+115F/U+1160 to the blank glyph list is the best
> > way, but it works. Keith, could you consider this?
>
> The blank glyph list is supposed to be filled with all of the Unicode
> values which have an empty visual representation.  It's a hack to work
...

> I adapted the data I found in Mozilla for this purpose, hence the similar
> issues you found in the two programs.

  Thank you for going through the Unicode  tables to
come up with a more extensive list.  I've just posted your list to bugzilla
bug 167136 mentioned previously.

> I'm reading through the Unicode tables looking for other blank values,
> so far I've found:
>
> Unicode range added? comments
>
> U+180B - U+180E   no  (but I don't have a Mongolian font to check against)
> U+200C - U+200F  yes  (the Unicode description isn't clear)
> U+2028 - U+2029 no  (these seem like they're supposed to be drawn)
> U+202A - U+202F  yes  (these also appear blank from the description)
> U+3164 yes  (HANGUL FILLER, similar to U+1160)
> U+FEFF   yes  (byte order detector (ZERO WIDTH NO-BREAK SPACE))
> U+FFA0 yes   HALFWIDTH HANGUL FILLER (similar to U+3164)
> U+FFF9 - U+FFFByes   INTERLINEAR ANNOTATION marks for furigana

> Rules for inclusion -- if a font could reasonably draw these as blank,
> they should be included in the list.  The idea is to ignore empty glyphs
> which should always have some visual representation.

  I think that U+200C/U+200D(ZWNJ, ZWJ) are meant to be used mainly(
though not exclusively. Latin ligature formation may also be controlled
by them.) with Indic scripts and fonts for Indic scripts are supposed to
have some OT tables built-in to map a sequence of characters including
ZWNJ/ZWJ to appropriate glyph(s). As for U+200E/U+200F and U+202A -
U+202F, I guess a lower-level layer like fontconfig is never supposed to
see them because they have to be taken care of at a higher level(layout.
e.g. Pango?).  Nonetheless, it seems like it's harmless(except for a
little performance hit, if any) to include them in the blank glyph list.
The same appears true of U+FFF9 - U+FFFB.

  BTW,  although depcecated, U+206A - U+206D seem to have to be included
as well.  U+206E and U+206F may or may not have to be added. I'm not
sure what they're for.

  Jungshik

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Re: [Fonts]blank glyph list in fonts.config

[James H. Cloos Jr.]

> "Keith" == Keith Packard <[EMAIL PROTECTED]> writes:

Keith> 0x1680 

AIUI, and I do not read Ogham, U+1680 is only blank in some fonts, and
is a horizontal line in others.

-JimC

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Re: [Fonts]blank glyph list in fonts.config

[Keith Packard]

Around 17 o'clock on Sep 7, "James H. Cloos Jr." wrote:

> AIUI, and I do not read Ogham, U+1680 is only blank in some fonts, and
> is a horizontal line in others.

Yes, that's the same reading I had of the spec.  The question isn't 
whether the glyphs are always blank, but whether finding an empty glyph
is acceptable, or whether the glyph must always produce an image.

In this case, because the glyph may reasonably be displayed as a blank, 
the unicode value should be included in the list of acceptable blank
encodings.

Keith PackardXFree86 Core TeamHP Cambridge Research Lab


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