Function sdl2_sys::SDL_GetSurfaceAlphaMod

pub unsafe extern "C" fn SDL_GetSurfaceAlphaMod(
    surface: *mut SDL_Surface, 
    alpha: *mut Uint8
) -> c_int

\brief Get the additional alpha value used in blit operations.

\param surface The surface to query. \param alpha A pointer filled in with the current alpha value.

\return 0 on success, or -1 if the surface is not valid.

\sa SDL_SetSurfaceAlphaMod()