pango-layout-line-extents (line)

iter -- a pango-layout-iter instance

ink-rect -- a pango-rectangle instance with the extents of the glyph string as drawn, or NULL
logical-rect -- a pango-rectangle instance with extents of the glyph string, or NULL

Computes the logical and ink extents of a layout line. See the function pango-font-glyph-extents for details about the interpretation of the rectangles.