A region is scalable because its coordinates are specified in world coordinates. On a drawing surface, however, its interior is dependent on the size and shape of the pixels representing it. An application can use regions to clamp the output of drawing operations. The window manager uses regions to define the drawing area of these regions are called clipping regions. An application can also use regions in hit-testing operations, such as checking whether a point or a rectangle intersects a region. An application can fill a region by using a Brush object. This class uses the Win32 GDI API's for handling regions. The GDI+ version System.Drawing.Region class just seems to be buggy and too slow.

Region メンバ
C1.Framework.Drawing.Gdi 名前空間