xor in region%

Sets the region to the xoring of itself with the given region (i.e., contains points that are enclosed by exactly one of the two regions).

This region's DC and given region's DC must be the same.

The result is always reliable for unsmoothed drawing. For smoothed drawing, the result is consistent across platforms and devices, but it is not necessarily a true xoring. An xoring corresponds to combining the sub-paths of this region with the reversed sub-paths of the given region. The result uses an 'odd-even fill if either of the region uses an 'odd-even fill (otherwise using a 'winding fill). Consequently, the result is a reliable xoring only for certain input regions. For example, it is reliable for atomic and xoring regions that all use 'even-odd fill.

• (send a-region xor rgn) -> void
     rgn : region% object