Fills the region specified by pRgn with the brush specified by pBrush.
A pointer to the region to be filled. The coordinates for the given region are specified in logical units.
Identifies the brush to be used to fill the region.
Nonzero if the function is successful; otherwise 0.
The brush must either be created using the CBrush member functions CreateHatchBrush, CreatePatternBrush, CreateSolidBrush, or be retrieved by GetStockObject.