Use this function to check whether a rectangle has no area.
const SDL_Rect* r)SDL_bool SDL_RectEmpty(
the SDL_Rect structure representing the rectangle to check
Returns SDL_TRUE if the rectangle has no area or SDL_FALSE if it does; see Remarks for details.
If the rectangle defined by r is NULL or has a width or height <= 0 it has no area and this function returns SDL_TRUE. If both width and height are > 0 the rectangle has area and this function returns SDL_FALSE.