Rasterization#
Drawing lines on a monitor involves rasterization, Bresenham is one of the best known methods. A similar algorithm, based on Zigl, evaluates the line errors or differences between the theoretical and actual line. This leads to a pro-active method of antialiasing.
Similarly rasterized circle algorithms from Bresenham and Zigl led to antialiased circles. PIL already has a normal arc, therefore there is no need to duplicate this, but there is no antialiased arc, which will be derived from the antialiased circle.