Unity 滚轮实现UGUI ScrollView的缩放

public class ResizeScrollEvent : UnityEvent<float> ｛ ｝
public class UIScroll : MonoBehaviour, IScrollHandler
｛
    public float minFactor = 1;
    public float maxFactor = 3;
    public bool wholeSizeFactor = true;
    private ResizeScrollEvent _onResize = new ResizeScrollEvent();
    private float _sizeFactor = 1f;
    public ResizeScrollEvent OnResize ｛ get ｛ return _onResize; ｝ ｝
    public float SizeFactor
    ｛
        get
        ｛
            if (wholeSizeFactor)
                return Mathf.Round(_sizeFactor);
            return _sizeFactor;
        ｝
        set
        ｛
            SetFactor(value);
        ｝
    ｝
    [SerializeField]
    RectTransform content;
    [SerializeField]
    RectTransform viewport;
    Rect _rect;
    Vector2 _focusPos;
    void Start()
    ｛
        _rect = GetWorldRect(viewport);
        _focusPos = _rect.center;
    ｝
    public static Rect GetWorldRect(RectTransform rt)
    ｛
        Vector3[] cors_ = new Vector3[4];
        rt.GetWorldCorners(cors_);
        Vector2 center = cors_[0];
        float width = Mathf.Abs(cors_[0].x - cors_[2].x);
        float height = Mathf.Abs(cors_[0].y - cors_[2].y);
        Rect rect_ = new Rect(center.x, center.y, width, height);
        return rect_;
    ｝
    private void SetFactor(float value)
    ｛
        value = ClampFactorValue(value);
        if (value != _sizeFactor)
        ｛
            _sizeFactor = value;
            ChangeSizeFactor(_sizeFactor);
            _onResize.Invoke(_sizeFactor);
        ｝
    ｝
    private void ChangeSizeFactor(float v)
    ｛
　　　　 Vector2 viewportSize_ = _rect.size;
 
        //缩放过程中的焦点位置（此处为中心位置）
//_focusPos = _rect.center;
        Rect contentRect_ = GetWorldRect(content);
        Vector2 contentSize_ = contentRect_.size;
        Vector2 contentCenter_ = contentRect_.center;
        Vector2 contentCenter2ViewportCenter_ = _focusPos - contentCenter_;
        float centerPosPercentX_ = contentCenter2ViewportCenter_.x / contentSize_.x;
        float centerPosPercentY_ = contentCenter2ViewportCenter_.y / contentSize_.y;
        Vector2 scorllSize_ = viewportSize_ + (v - 1) * viewportSize_ / 5;
        content.SetSizeWithCurrentAnchors(RectTransform.Axis.Horizontal, scorllSize_.x);
        content.SetSizeWithCurrentAnchors(RectTransform.Axis.Vertical, scorllSize_.y);
        Vector2 sizeDelta_ = scorllSize_ - contentSize_;
        Vector2 posOffset_ = new Vector2(sizeDelta_.x * -centerPosPercentX_, sizeDelta_.y * -centerPosPercentY_);
        content.anchoredPosition += posOffset_;
        Vector3[] viewCorner_ = new Vector3[4];
        Vector3[] contentCorner_ = new Vector3[4];
        viewport.GetWorldCorners(viewCorner_);
        content.GetWorldCorners(contentCorner_);
        float xFixDelta_ = 0;
        float yFixDelta_ = 0;
        if (viewCorner_[0].x < contentCorner_[0].x) xFixDelta_ = viewCorner_[0].x - contentCorner_[0].x;
        if (viewCorner_[0].y < contentCorner_[0].y) yFixDelta_ = viewCorner_[0].y - contentCorner_[0].y;
        if (viewCorner_[2].x > contentCorner_[2].x) xFixDelta_ = viewCorner_[2].x - contentCorner_[2].x;
        if (viewCorner_[2].y > contentCorner_[2].y) yFixDelta_ = viewCorner_[2].y - contentCorner_[2].y;
        content.anchoredPosition += new Vector2(xFixDelta_, yFixDelta_);
    ｝
    private float ClampFactorValue(float value)
    ｛
        float factor_ = Mathf.Clamp(value, minFactor, maxFactor);
        if (wholeSizeFactor) factor_ = Mathf.Round(factor_);
        return factor_;
    ｝
    public void OnScroll(PointerEventData eventData)
    ｛
        if (!isActiveAndEnabled) return;

_focusPos = eventData.position;//焦点为鼠标所在位置 float delta_ = 0;
        if (Mathf.Abs(eventData.scrollDelta.x) > Mathf.Abs(eventData.scrollDelta.y))
            delta_ = eventData.scrollDelta.x;
        else delta_ = eventData.scrollDelta.y;
        SetFactor(_sizeFactor + delta_);
    ｝
｝

public class NewBehaviourScript : MonoBehaviour
｛
    [SerializeField]
    Slider scaleSlider;
    [SerializeField]
    Text sliderValue;
    [SerializeField]
    UIScroll scrollView;
	void Start ()
    ｛
        scaleSlider.wholeNumbers = true;
        scaleSlider.minValue = 1;
        scaleSlider.maxValue = 10;
        scaleSlider.onValueChanged.AddListener(OnSliderValueChange);
        scrollView.minFactor = scaleSlider.minValue;
        scrollView.maxFactor = scaleSlider.maxValue;
        scrollView.wholeSizeFactor = true;
        scrollView.OnResize.AddListener(OnScrollResized);
        scrollView.SizeFactor = 1;
	｝
    private void OnScrollResized(float value)
    ｛
        scaleSlider.value = value;
    ｝
    private void OnSliderValueChange(float value)
    ｛
        scrollView.SizeFactor = value;
        sliderValue.text = value.ToString();
    ｝
｝