在子项的位置更改时执行的回调。
onValueChanged is used to watch for changes in the ScrollRect object.
The onValueChanged call will use the UnityEvent.AddListener API to watch for
changes. When changes happen script code provided by the user will be called.
The UnityEvent.AddListener API for ScrollRect.onValueChanged takes a Vector2.
Note: The editor allows the onValueChanged value to be set up manually. For example the
value can be set to run only a runtime. The object and script function to call are also
provided here.
The onValueChanged variable can be alternatively set-up at runtime. The script example below
shows how this can be done. The script is attached to the ScrollRect object.
no example available in C#