Re: 23.0.60; Heavy display problems with new font backend

[sand@blarg.net]

David Hansen writes:
> > A fellow Neep Alt-er!  Have you also tried the Neep Alt ISO10646-1
> > registry fonts from Debian's xfonts-jmk package?  When I use the
> > ISO10646 fonts with the new font backend, Emacs seems to think that
> > the font is missing large quantities of codepoints.  Left and right
> > quotes, for example, show up using double-width Chinese fonts.  I'm
> > curious whether other people see the same thing.
> 
> I noticed that problem not only with the neep font but also with Monaco
> and the fairly complete DejaVu Mono font.  I even reported it as a bug,
> but it may be possible that this is some limited understanding of
> dealing with fontsets on my side.
> 
> It may be worth a look how rxvt selects fonts.  When looking at the
> unicode test file it looks far better in urxvt, no matter which font I
> specify as the default.

I traced the fonts being sent to ftfont_has_char() and discovered that
for a letter like LATIN SMALL LETTER S ACUTE (#x15b), Emacs was asking
about the Neep Alt family as expected, but only about fonts with the
iso8859-1 registry/encoding within that family.  When I removed the
iso8859-1 fonts entirely from the font path and HUPed the font server,
Emacs started asking about the iso10646-1 registry/encoding fonts, and
those *were* found and displayed correctly.  (On the other hand, the
mode line's file name---and just the mode line's file name---dropped
down to a different font.)  So:

 1. It looks like Emacs has a problem determining the right registry
 to use for certain code points, or the font picking fallback code has
 problems.

 2. The file name display code may not be correctly integrated with
 the new font backend.

At this point I think I need to get more familiar with the contents of
etc/DEBUG...

Derek

-- 
Derek Upham
sand@blarg.net