Each arc is specified by a rectangle and two angles. The center of the circle or ellipse is the center of the rectangle, and the major and minor axes are specified by the width and height.
Positive angles indicate counterclockwise motion, and negative angles indicate clockwise motion.
These coordinates can be fractional and so are not truncated to discrete coordinates. The path should be defined by the ideal mathematical path. Otherwise, the intersecting pixels of intersecting arcs are drawn multiple times. Specifying an arc with one endpoint and a clockwise extent draws the same pixels as specifying the other endpoint and an equivalent counterclockwise extent, except as it affects joins. If the last point in one arc coincides with the first point in the following arc, the two arcs will join correctly.