Re: Pango Status Report, 9 Feb 2000

[Steve Underwood <steveu coppice org>]

Owen Taylor wrote:

> Recent progress:
>
>  In the last few weeks, I've been concentrating my efforts
>  on the font system, both for the rendering-independent
>  interfaces and for X.
>
>  The general design for the font independent stuff is pretty
>  similar to lots of existing systems ... whether Java or
>  gnome-font. The exact set of properties is based most
>  closely on the font properties from CSS2.
>
>  You can check out the API for this at:
>
>   http://www.pango.org/api/pango-fonts.html
>
>  The X work I've done is mostly implementing this API for the X
>  platform, and also improving the selection algorithms for finding
>  XLFDs to match a particular PangoFontDescription and size. (I'm now
>  just listing all fonts from the X server with XListFonts() and
>  doing all the matching client side.)
>
>  The other thing I've been working on is getting fonts to report
>  their own coverage maps. This will allow better handling of
>  selecting fonts with fallbacks to other fonts for character
>  points not handled by the first font.
>
>  The implementation of this is pretty much complete, though it isn't
>  yet used by the shaping core.

How do you plan to do the fallback? Will you require a list of fallback fonts to
be defined by the application, or do you aim to have some automated approach, by
scanning available fonts? Pango 0.6 doesn't yet handle the fallback, and so it
gives pretty crazy results if I select anything but unifont. I can't see the
direction in which things are going, though. If I try to pick, say, the fixed
font, where I have GB, JIS, and Big5 fonts called fixed, Pango doesn't need to
fallback. It just needs to check all the fonts called fixed, to find one with an
available glyph. I can't see your strategy for handling this, though. Right now
it seems to simply reject the characters not covered by the first font it tries.
Am I missing something?

Steve