When constructing circular or elliptical arcs, it is sometimes necessary to specify which of several possible arcs you want. For example, if you ask for a circular arc from the point (1, 0) to the point (0, 1) with a radius of 1, there are four possible solutions:

• An arc with a swept angle of 90 degrees, with center point at (0, 0)
• An arc with a swept angle of -270 degrees, with center point at (0, 0)
• An arc with a swept angle of -90 degrees, with center point at (1, 1)
• An Arc with a swept angle of 270 degrees, with center point at (1, 1)

The SweptAngle type is used in these cases to specify which arc you want.