Version: 2018.2

UIBehaviour.OnRectTransformDimensionsChange

マニュアルに切り替える
protected void OnRectTransformDimensionsChange ();

説明

This callback is called if an associated RectTransform has its dimensions changed.

The call is also made to all child rect transforms, even if the child transform itself doesn't change - as it could have, depending on its anchoring.