a #PangoFontDescription structure. %NULL means that the font description from the context will be used.
language tag used to determine which script to get the metrics for. %NULL means that the language tag from the context will be used. If no language tag is set on the context, metrics for the default language (as determined by pango_language_get_default()) will be returned.
a #PangoFontMetrics object. The caller must call pango_font_metrics_unref() when finished using the object.
Get overall metric information for a particular font description. Since the metrics may be substantially different for different scripts, a language tag can be provided to indicate that the metrics should be retrieved that correspond to the script(s) used by that language.
The #PangoFontDescription is interpreted in the same way as by pango_itemize(), and the family name may be a comma separated list of figures. If characters from multiple of these families would be used to render the string, then the returned fonts would be a composite of the metrics for the fonts loaded for the individual families.