Windows includes several additional drawing functions that work with RECT (rectangle) structures and regions. A region is an area of the screen that is a combination of rectangles, polygons, and ellipses.
These three drawing functions require a pointer to a rectangle structure:
FillRect (hdc, &rect, hBrush) ; FrameRect (hdc, &rect, hBrush) ; InvertRect (hdc, &rect) ;
In these functions, the rect parameter is a structure of type RECT with four fields: left, top, right, and bottom. The coordinates in this structure are treated as logical coordinates.
FillRect fills the rectangle (up to but not including the right and bottom coordinates) with the specified brush. This function doesn't require that ...