How can I get PangoFontMetrics for a specified font family and font size

[n179911 <n179911 gmail com>]

Hi,

In pango, how can I get PangoFontMetrics for a specified font family
and font size?

Font http://library.gnome.org/devel/pango/unstable/pango-Fonts.html#PangoFontDescription

I think I can create a PangoFontDescription using
pango_font_description_new and then set the family and size of the
PangoFontDescription.

But from then on, how can I construct a PangoFont pointer so that I can call
PangoFontMetrics *  pango_font_get_metrics              (PangoFont *font,
                                                         PangoLanguage
*language);

Thank you.