class interface DRAWABLE_CHORD creation make feature(s) from DRAWABLE_ELLIPSE -- Position set_bounding_rectangle (rect: RECTANGLE) -- Set the rectangle defining the ellipse from which -- the arc is extracted. require valid_rectangle: rect /= Void feature(s) from DRAWABLE_ARC -- Position set_starting_secant (pt: POINT) -- Set the point defining the starting radial from which -- the arc will be drawn. The radial is the line containing -- this point and the centre of the ellipse. require valid_point: pt /= Void set_ending_secant (pt: POINT) -- Set the point defining the ending radial to which -- the arc will be drawn. require valid_point: pt /= Void set_direction_anticlockwise -- Draw ellipse anticlockwise (default). ensure done: clockwise = false set_direction_clockwise -- Draw ellipse clockwise. ensure done: clockwise = true invariant valid_ellipse: bounding_rectangle /= Void; valid_arc: start /= Void and final /= Void; end of DRAWABLE_CHORD