Function sdl2_sys::SDL_GetWindowOpacity

pub unsafe extern "C" fn SDL_GetWindowOpacity(
    window: *mut SDL_Window, 
    out_opacity: *mut f32
) -> c_int

\brief Get the opacity of a window.

If transparency isn't supported on this platform, opacity will be reported as 1.0f without error.

\param window The window in question. \param out_opacity Opacity (0.0f - transparent, 1.0f - opaque)

\return 0 on success, or -1 on error (invalid window, etc).

\sa SDL_SetWindowOpacity()