unity3d ngui dragableCamera 与scrollbar

ngui  拖动物体的第二个例子里没有和scrollbar

自己写了一个

using UnityEngine;
using System.Collections;

public class ScrollBar : MonoBehaviour {
    public UIScrollBar sb;
    public UIDraggableCamera dragCam;
    private bool isPressed;
    public Transform scrollBarBack;

    private Vector3 lastCamPos;

	// Use this for initialization
	void Start () {
        if (sb == null && dragCam == null) {
            Debug.Log("not set value");
        }

        lastCamPos = dragCam.transform.localPosition;
        isPressed = false;
        //sb.onChange += setScrollvalue;
	}
	
	// Update is called once per frame
	void Update () {
        if (isPressed) {
            isPressed = Input.touchCount == 1&&Input.GetMouseButton(0);
        }

        if (!isPressed)
        {
            Vector3 nowpos = dragCam.transform.localPosition;
            if (lastCamPos != nowpos)
            {
                float hhh = nowpos.y - lastCamPos.y;
                float h = (nowpos - lastCamPos).magnitude*(nowpos.magnitude>lastCamPos.magnitude?-1:1);
                float H = h;
                Bounds b = NGUIMath.CalculateAbsoluteWidgetBounds(dragCam.rootForBounds);//整个面板的bounds
                float hh = b.extents.y * Screen.height * dragCam.scale.y + b.extents.x * Screen.width * dragCam.scale.x;
                h = h / hh;
                sb.scrollValue += h;
                lastCamPos = nowpos;
                //Debug.Log("HH/"+H+"   h/"+h+"  hh/"+hhh+" scrollv/"+sb.scrollValue);
            }
        }
	}

    void OnPress(bool pressed)
    {
        isPressed = true;
        Debug.Log("On pressed/"+isPressed);
        if (enabled && NGUITools.GetActive(gameObject)&&dragCam!=null)
        {
            dragCam.Press(pressed);
        }
    }

    void OnDrag(Vector2 delta)
    {
        //Debug.Log("delta/"+delta);
        Bounds b = NGUIMath.CalculateAbsoluteWidgetBounds(dragCam.rootForBounds);//整个面板的bounds

        float h=scrollBarBack.localScale.y;//scrollbar的高度
        float w = scrollBarBack.localScale.x;
       
        delta.y =dragCam.scale.y* (delta.y / h) * b.extents.y * Screen.height ;
        delta.x =dragCam.scale.x* (delta.x / w) * b.extents.x * Screen.width;
        Debug.Log("panel bounds:" + b + "   scale/" + dragCam.scale+ "  delta/" + delta);
        

        if (enabled && NGUITools.GetActive(gameObject) && dragCam != null)
        {
            dragCam.Drag(delta*-1);
        }
    }

}