gdk:screen-resolution (object)

object -- a gdk:screen object
dpi -- a double float for the resolution in "dots per inch"

The accessor for the resolution slot of the gdk:screen class the resolution for font handling on the screen. Returns -1 if no resolution has been set.

This is a scale factor between points specified in a pango:font-description instance and Cairo units. The default value is 96, meaning that a 10 point font will be 13 units high (10 * 96 / 72 = 13.3).