The Win32 API provides a number of functions that use the brush currently selected into a device context to perform bitmap operations. For example, the PatBlt function replicates the brush in a rectangular region within a window, and the FloodFill function replicates the brush inside an area in a window bounded by the specified color (unlike PatBlt, FloodFill does fill nonrectangular shapes).
The FloodFill function replicates the brush within a region bounded by a specified color. However, unlike the PatBlt function, FloodFill does not combine the color data for the brush with the color data for the pixels on the display; it simply sets the color of all pixels within the enclosed region on the display to the color of the brush that is currently selected into the device context.