Am 28.04.2015 um 17:53 schrieb Urs Liska:
I think I have found something.
After some experimenting with a copy of font-config-get-font-file and
trying different approaches I could guess from the documentations
available I found that replacing an item in the FcPatternGetString
call this function returns the font name and not the Postscript name
or the font file.
The following preliminary function (if added to font-config-scheme.cc)
returns either the Font Name (if the font exists) or "Emmentaler-11"
(on my system) if it doesn't exist. I assume it would return other
names on other systems:
LY_DEFINE (ly_font_config_font_exists, "ly:font-config-font-exists",
1, 0, 0,
(SCM name),
"Determing if font @var{name} exists.")
{
LY_ASSERT_TYPE (scm_is_string, name, 1);
FcPattern *pat = FcPatternCreate ();
FcValue val;
val.type = FcTypeString;
val.u.s = (const FcChar8 *)ly_scm2string (name).c_str (); //
FC_SLANT_ITALIC;
FcPatternAdd (pat, FC_FAMILY, val, FcFalse);
FcResult result;
SCM scm_result = SCM_BOOL_F;
FcConfigSubstitute (NULL, pat, FcMatchFont);
FcDefaultSubstitute (pat);
pat = FcFontMatch (NULL, pat, &result);
FcChar8 *str = 0;
if (FcPatternGetString (pat, FC_FAMILY, 0, &str) == FcResultMatch)
scm_result = scm_from_utf8_string ((char const *)str);
FcPatternDestroy (pat);
return scm_result;
}
Now I get stuck with C++ basics, namely types, references and
pointers, but it should be possible to achieve something with the
following approach:
In the line
scm_result = scm_from_utf ...
"str" holds the result from this match.
If this matches the originally passed "name" argument the return value
should be set to SCM_BOOL_T.
This should be dead easy, but I don't know to perform this comparison.
If someone gives me a helping hand here we would get a function
ly:font-config-font-exists that returns #t or #f depending on the
existence of the font.
Please ...
Best
Urs
Wrapping this Scheme function around that:
fontExists =
#(define-scheme-function (parser location font-name)(string?)
(string=? font-name (ly:font-config-font-exists font-name)))
shows that my idea is right: The C++ function returns the family name of
either the given font or the (system-dependent) fallback font. Now all
there would be to it is moving the comparison of the latter Scheme
function to the C++ function .
Urs
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