code: public boolean isLoaded () {
      Try<Image> cur = state.result();
      return cur != null && cur.isSuccess();
    }
docs: Returns whether this image is successfully loaded. If it is still loading, or loading failed,
  {@code false} will be returned. In general you'll want to react to {@link #state}, but this
  method is useful when you need to assert that something is only allowed on a fully loaded
  image.