SDL_FillRect- This function performs a fast fill of the given rectangle with
int SDL_FillRect(SDL_Surface *dst, SDL_Rect *dstrect, Uint32 color);
This function performs a fast fill of the given rectangle with color. If dstrect
is NULL, the whole surface will be filled with color.
The color should be a pixel of the format used by the surface, and can be
generated by the SDL_MapRGB function.
If there is a clip rectangle set on the destination (set via SDL_SetClipRect)
then this function will clip based on the intersection of the clip rectangle and
the dstrect rectangle.
This function returns 0 on success, or -1 on error.
SDL_MapRGB, SDL_BlitSurface, SDL_Rect