Allocate an empty surface (must be called after SDL_SetVideoMode)
If depth is 8 bits an empty palette is allocated for the surface, otherwise a 'packed-pixel' SDL_PixelFormat is created using the [RGBA]mask's provided (see SDL_PixelFormat). The flags specifies the type of surface that should be created, it is an OR'd combination of the following possible values.
| SDL_SWSURFACE | SDL will create the surface in system memory. This improves the performance of pixel level access, however you may not be able to take advantage of some types of hardware blitting. |
| SDL_HWSURFACE | SDL will attempt to create the surface in video memory. This will allow SDL to take advantage of Video->Video blits (which are often accelerated). |
| SDL_SRCCOLORKEY | With this flag SDL will attempt to find the best location for this surface, either in system memory or video memory, to obtain hardware colorkey blitting support. |
| SDL_SRCALPHA | With this flag SDL will attempt to find the best location for this surface, either in system memory or video memory, to obtain hardware alpha support |