public way to get PangoFontDescription from FcPattern or so

[Kang Jeong-Hee <Keizi mail co kr>]

Hi.

I'm willing to support 'webfont' for http://gybe.sf.net/.

the routine will be:
 1. take a font file, specified by CSS or HTML document.
 2. load the file into fontconfig.
 3. give a family name the font loaded.

and now, gtk widget should be set with the family name.
gtk_widget_modify_font() or other method require PangoFontDescription.
how to build the PangoFontDescription?

* _pango_fc_font_desc_from_pattern(), is private function
build a font_desc from FcPattern.

FcPattern is return by FcFontMatch() thru this procedure:
        FcConfigGetCurrent() return a FcConfig.
        FcConfigAppFontAddFile() add the font file into FcConfig.
        FcNameParse() return a FcPattern from the value of 'font-family'.
        FcFontMatch() try a match with FcConfig and FcPattern,
         and return a good match of FcPattern.
         this is the FcPattern for pango.

* pango_font_description_from_string()
build a font_desc from a string, the 'font-family' value of CSS.
(what a simple!)

in this case, how to ensure that the font which added at runtime
recognized by pango? what happen after setting the font_desc to gtkwidget?
how to put the new FcConfig into pango, after FcConfigAppFontAddFile()?

let me listen to your comment.

thx
kz.