Re: [d.love@dl.ac.uk: x-font-family-list gives incomplete results]

["Jan D." <jan.h.d@swipnet.se>]

Richard Stallman wrote:
> This seems like an important issue, so I am forwarding the message here.
> 
> ------- Start of forwarded message -------
> To: bug-gnu-emacs@gnu.org
> From: Dave Love <d.love@dl.ac.uk>
> Date: 20 Jan 2003 18:32:46 +0000
> Subject: x-font-family-list gives incomplete results
> Sender: bug-gnu-emacs-bounces+rms=gnu.org@gnu.org
> 
> `x-font-family-list' misses a lot, specifically fonts which are
> suitable for offering the user as the default.  E.g. on a Debian
> stable system I have this:
> 
> (x-font-family-list)
>   => (("clean" . t) ("clearlyu") ("clearlyu alternate glyphs") ("clearlyu arabic extra") ("clearlyu ligature") ("clearlyu pua") ("fangsong ti" . t) ("fixed" . t) ("gothic" . t) ("mincho" . t) ("newspaper") ("nil" . t) ("open look cursor") ("open look glyph") ("song ti" . t) ("unifont" . t))
> 
> (face-font 'default)
>   => "-B&H-LucidaTypewriter-Medium-R-Normal-Sans-12-120-75-75-M-70-ISO8859-1"
> 
> Note that the lucidatypewriter I'm actually using isn't listed and I
> have 64 families according to xfontsel.
> 
> The code implementing this looks superficially correct to me.  Am I
> missing something?

There is a bug here.  x-font-family-list does this:

   for (limit = 500;;)
     {
       specbind (intern ("font-list-limit"), make_number (limit));
       nfonts = font_list (f, Qnil, Qnil, Qnil, &fonts);

       if (nfonts == limit)
	{
	  free_font_names (fonts, nfonts);
	  limit *= 2;
	}
       else
	break;
     }

The problem is that font_list return a filtered list.  For instance, duplicates 
are removed, and scalable fonts may also be removed (see variable 
scalable-fonts-allowed).  If I do

% xlsfonts | wc

I get 9568, but if I do

% xlsfonts | sort -u | wc

I get 5690.

So if there is just one duplicate or if scalable fonts are filtered, 
x-font-family-list stops increasing limit and stops reading font names.

One alternative solution would be to make maxnames passed to x_list_fonts 
(xterm.c) mean "get all font names" if it is less than zero.  This also affects 
w32 and mac, since those ports also have a function with this name.

Making maxnames < 0 mean "all font names" should perhaps be propagated into 
Fx_list_fonts?  Now it uses an arbitrary limit of 2000 if maximum is not given, 
which is too few on many machines.


	Jan D.