【UGUI】侧面滑出的菜单栏，宽度自适应

using System.Collections;  
using System.Collections.Generic;  
using UnityEngine;  
using UnityEngine.UI;  
public class UICont : MonoBehaviour ｛  
    public RectTransform mainUI;  
    public Button showHideBtn;  
    public RepeatButton dragBtn;  
    private bool m_isShow = true;  
   // public RectTransform   
    // Use this for initialization  
    void Start () ｛  
        dragBtn.onPress.AddListener(DragBtn);  
        showHideBtn.onClick.AddListener(ShowHide);  
    ｝  
    void ShowHide() ｛  
        Vector3 vec3Tmp = mainUI.position;  
        if(m_isShow) ｛  
            vec3Tmp.x = -mainUI.sizeDelta.x;  
            iTween.MoveTo(mainUI.gameObject, vec3Tmp, 1f);  
            m_isShow = false;  
        ｝ else ｛  
            vec3Tmp.x = 0;  
            iTween.MoveTo(mainUI.gameObject, vec3Tmp, 1f);  
            m_isShow = true;  
        ｝  
    ｝  
    void DragBtn() ｛  
        Vector2 vec2Tmp = mainUI.sizeDelta;  
        vec2Tmp.x = Mathf.Clamp(Input.mousePosition.x, 100, 500);  
        mainUI.sizeDelta = vec2Tmp;  
    ｝  
    // Update is called once per frame  
    //void Update () ｛  
    //｝  
｝  

/******* 
 *  
 * button长按的代理 
 * http://blog.csdn.net/lyh916/article/details/51454673 
 *  
 *  
 * */  
using UnityEngine;  
using System.Collections;  
using UnityEngine.EventSystems;  
using UnityEngine.Events;  
public class RepeatButton : MonoBehaviour, IPointerDownHandler, IPointerUpHandler, IPointerExitHandler ｛  
    public bool invokeOnce = false;//是否只调用一次  
    private bool hadInvoke = false;//是否已经调用过  
    public float interval = 0.1f;//按下后超过这个时间则认定为"长按"  
    private bool isPointerDown = false;  
    private float recordTime;  
    public UnityEvent onDown = new UnityEvent();//按下时调用  
    public UnityEvent onPress = new UnityEvent();//按住时调用  
    public UnityEvent onRelease = new UnityEvent();//松开时调用  
    void Start() ｛  
    ｝  
    void Update() ｛  
        if (invokeOnce && hadInvoke)  
            return;  
        if (isPointerDown) ｛  
            if ((Time.time - recordTime) > interval) ｛  
                onPress.Invoke();  
                hadInvoke = true;  
            ｝  
        ｝  
    ｝  
    public void OnPointerDown(PointerEventData eventData) ｛  
        isPointerDown = true;  
        recordTime = Time.time;  
        onDown.Invoke();  
    ｝  
    public void OnPointerUp(PointerEventData eventData) ｛  
        isPointerDown = false;  
        hadInvoke = false;  
        onRelease.Invoke();  
    ｝  
    public void OnPointerExit(PointerEventData eventData) ｛  
        //isPointerDown = false;  
        //hadInvoke = false;  
        //onRelease.Invoke();  
    ｝  
｝