cairo-clip-extents (cr)

cr -- a cairo-t context

x1 -- a double float for the left of the resulting extents
y1 -- a double float for the top of the resulting extents
x2 -- a double float for the right of the resulting extents
y2 -- a double float for the bottom of the resulting extents

Computes a bounding box in user coordinates covering the area inside the current clip.