Re: Unicode repertoire of X11 fonts

From: Erik van der Poel (erik@netscape.com)
Date: Mon Dec 07 1998 - 01:09:53 EST


Markus Kuhn wrote:
>
> (Minor terminology nitpicking: I think talking about UCS-2 doesn't
> make sense in the context of a font, because glyphs in fonts have just
> integer numbers and not byte sequences assigned to them, and UCS-2 (at
> least for me) refers only to how to store a sequence of characters as a
> byte sequence.)

Yes, but the XChar2b struct is simply filled with the high and low byte
of the UCS-2 character code, right?

The iso10646-1 fonts use a one-to-one character-to-glyph mapping, right?
Or do you somehow support true character to glyph mapping?

> We left the option for future
> standardization to indicate a subset (such as MES2) in the
> CHARSET_ENCODING field.

So, until the subsets are standardized in the future, the application
programmer needs to look at the per_char array (if that info is
required).

> > Is the application supposed to look at the per_char array of the
> > XFontStruct to find out which characters are available? My guess is
> > that's the only way...
>
> You can do either this, or leave it to Xlib to display the DEFAULT_CHAR
> specified in the font for all characters that are not in the font.

Some applications need to know which glyphs are available. For example,
in CSS you can say e.g.:

  font-family: helvetica, mincho, serif

The implementation is supposed to go down this list until it finds a
font that contains the glyph that you need. The generic names such as
"serif" are themselves typically defined in terms of yet another list of
fonts.

Erik



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