code: def ink_extents(self):
          
          extents = ffi.new('double[4]')
          cairo.cairo_recording_surface_ink_extents(
              self._pointer, extents + 0, extents + 1, extents + 2, extents + 3)
          self._check_status()
          return tuple(extents)
docs: Measures the extents of the operations
          stored within the recording-surface.
          This is useful to compute the required size of an image surface
          (or equivalent) into which to replay the full sequence
          of drawing operations.
  
          :return: A ``(x, y, width, height)`` tuple of floats.