Maximum height of line of text in Pango

[Dominique Würtz <housirer gmx de>]

Hi,

how can I efficiently obtain the minimum height in pixels which is 
guaranteed to cover a text line in a given font?

Basically, I need something like

(metrics.get_ascent() + metrics.get_descent()) / pango.SCALE

where metrics is a pango.FontMetrics. Unfotunately, the operation given 
above takes ages to compute and is thus not feasible in the context of 
drawing a widget to the screen.

Any ideas? Thank you in advance

Dominique