All SDL functions, enums, constants, and structures are fully wrapped with a nice (if barebones) interface. Nice generally meaning things such as: instead of calling sdl.GetWindowWidth(window), you can instead call: window.getWidth().
-- Corollary to having everything wrapped: certain pieces of the SDL library make no sense to wrap, due to facilities provided by Node. Two examples of this are the RWOps API, which is dealt with by stuff such as the fs module, or the Thread API which can't really work with Node. (would have to be used in the background by some C++ code to do things in another thread, or just use libuv)

All SDL_ttf functions, enums, constants, and structures are fully wrapped. Same nice features apply to ttf as to the main SDL library.

All SDL_image functions, enums, constants, and structures are fully wrapped.