能解释一下OffsetUI中enable分支中的这段代码吗？
if (_enable) {
float rx = Screen.width / _original.x;
float ry = Screen.height / _original.y;
if (rx < ry) {
float r = rx;
float cha = (1f - r) * Screen.height;
float x = (1f - r) / 2 * Screen.width;
float y = cha / 2f;
this.gameObject.transform.localScale = new Vector3 (r, r, 1);
this.gameObject.transform.localPosition = new Vector3 (x, y, 0);
_rect.sizeDelta = new Vector2 ((_original.x - Screen.width), cha / r);
} else {
float r = ry;
float cha = (1f - r) * Screen.width;
float y = (1 - r) / 2 * Screen.height;
float x = cha / 2f;
this.gameObject.transform.localScale = new Vector3 (r, r, 1);
this.gameObject.transform.localPosition = new Vector3 (x, y, 0);
_rect.sizeDelta = new Vector2 (cha / r, (_original.y - Screen.height));
}
}else中的代码应该是一个道理，为了让代码更完整一点， 就传上来了。
先说一下我自己的理解：
this.gameObject.transform.localScale = new Vector3 (r, r, 1);//这句应该是等比例缩放
this.gameObject.transform.localPosition = new Vector3 (x, y, 0);//这句应该是居中（结合上面x和y的值来看）
_rect.sizeDelta = new Vector2 ((_original.x - Screen.width), cha / r);//这句应该是变化_rect的大小， 但是不知道Vector2构造函数中的值有什么讲究
另外， _rect的大小需要单独做变化吗？难道不是随着父元素的值一起变化的吗？
