DejaVu vs. Lucida and `slant' face attribute

DejaVu vs. Lucida and `slant' face attribute

[Giorgos Keramidas]

Hi everyone,

I recently updated my Emacs installation to a CVS snapshot which
includes the new Xft backend code.  Things look great, and I'm quite
happy about the ability to use scalable monospaced fonts in my X11 based
Emacs sessions.

I noticed something odd, however.  A difference in the handling of the
`DejaVu Sans Mono' and `Lucida Sans Typewriter' fonts.

After setting the following X11 resources:

  Emacs.FontBackend: xft
  Emacs*font: DejaVu Sans Mono:size=12

Emacs correctly uses `DejaVu Sans Mono:style=Oblique' for displaying
slanted text in Gnus article buffers, i.e. for text with the
`gnus-cite-attribution' face property.

When I fire up the same Emacs build with:

  emacs -fn 'Lucida Sans Typewriter'

The same text is not slanted, italic or oblique.

The two fonts seem to have `Oblique' and `Bold Oblique' styles, when I
try to list them with fc-list(1):

  keramida@kobe:/home/keramida$ fc-list 'Lucida Sans Typewriter'
  Lucida Sans Typewriter:style=Bold
  Lucida Sans Typewriter:style=Oblique
  Lucida Sans Typewriter:style=Regular
  Lucida Sans Typewriter:style=Bold Oblique
  keramida@kobe:/home/keramida$ fc-list 'DejaVu Sans Mono'
  DejaVu Sans Mono:style=Bold Oblique
  DejaVu Sans Mono:style=Oblique
  DejaVu Sans Mono:style=Book
  DejaVu Sans Mono:style=Bold
  keramida@kobe:/home/keramida$

Any hints or help about troubleshooting why Emacs doesn't use the
`Lucida Sans Typewriter:style=Oblique' font for text with a face whose
`Slant' is `italic'?

When I use `C-u C-x =' on gnus-cite-attribution text, the output with
the Lucida font is:

%         character: F (70, #o106, #x46)
% preferred charset: ascii (ASCII (ISO646 IRV))
%        code point: 0x46
%            syntax: w	which means: word
%          category: a:ASCII graphic characters 32-126 (ISO646 IRV:1983[4/0])
% 	 	      l:Latin r:Japanese roman
%       buffer code: #x46
%         file code: not encodable by coding system windows-1252-unix
%           display: by this font (glyph code)
%      lucida sans typewriter:pixelsize=12:foundry=b&h:weight=regular:slant=roman:width=normal (#x29)
%
% Character code properties are not shown: customize what to show
%
% There are 2 overlays here:
%  From 240 to 299
%   evaporate            t
%   face                 gnus-cite-1
%  From 240 to 299
%   evaporate            t
%   face                 gnus-cite-attribution
%
%
% There are text properties here:
%   auto-composed        t
%   charset              windows-1252
%

When I use DejaVu Sans Mono, the same text shows the following output
with `C-u C-x =':

%         character: O (79, #o117, #x4f)
% preferred charset: ascii (ASCII (ISO646 IRV))
%        code point: 0x4F
%            syntax: w	which means: word
%          category: a:ASCII graphic characters 32-126 (ISO646 IRV:1983[4/0])
% 	 	      l:Latin r:Japanese roman
%       buffer code: #x4F
%         file code: not encodable by coding system windows-1252-unix
%           display: by this font (glyph code)
%      dejavu sans mono:pixelsize=12:foundry=unknown:weight=regular:slant=o:width=normal (#x32)
%
% Character code properties are not shown: customize what to show
%
% There are 2 overlays here:
%  From 240 to 299
%   evaporate            t
%   face                 gnus-cite-1
%  From 240 to 299
%   evaporate            t
%   face                 gnus-cite-attribution
%
%
% There are text properties here:
%   auto-composed        t
%   charset              windows-1252

I'm not sure why Emacs picks `slant=roman' in the case of the Lucida
font, so any help in tracking down more details is quite welcome :-)