Encapsulates a Windows graphics device interface (GDI) region.
A region is an elliptical or polygonal area within a window. To use regions, you use the member functions of class CRgn with the clipping functions defined as members of class CDC.
The member functions of CRgn create, alter, and retrieve information about the region object for which they are called.
For more information on using CRgn, see Graphic Objects.