[游戏开发]Unity 实现图标的拖拽功能

OnPointUp 不仅鼠标松开会调用，鼠标移动也会调用。
时间紧迫，只贴核心代码

using UnityEditor;
using UnityEngine;
using UnityEngine.UI;
using UnityEngine.EventSystems;
using UnityEngine.Events;
using System;
namespace Scripts.LuaApi
{
    public class DragItemArea : MonoBehaviour,IBeginDragHandler,IDragHandler,IEndDragHandler
    {
        public Graphic checkArea;
        public Graphic copyItem;
        private const string UI_CameraPath = "Root/_GameManager(Clone)/UGUISystem/Camera";//UI 相机 的 场景 路径
        private Camera UICamera;
        public Action<Graphic,object> beginEvent;
        public Action<object> endInAreaCallback;
        public Action<object> endCallback;
        private bool inEnter = false;
        public UnityEvent inEvent;
        public UnityEvent outEvent;
        public object data;
        private Vector2 lastMousePosition;
        public void SetBeginEvent(Action<Graphic,object> be)
        {
            this.beginEvent = be;
        }

        public void ResetEvent()
        {
            beginEvent = null;
            endInAreaCallback = null;
            endCallback = null;
        }
        public void SetEndInAreaCallback(Action<object> ee)
        {
            this.endInAreaCallback = ee;
        }
        public void SetEndCallback(Action<object> callbcak)
        {
            this.endCallback = callbcak;
        }
        public void SetData(object data)
        {
            this.data = data;
        }    
        private void Start()
        {
            if (UICamera == null)
            {
                var camera = GameObject.Find(UI_CameraPath);
                if (camera != null)
                {
                    UICamera = camera.GetComponent<Camera>();
                }
                else
                {
                    Debug.LogError($"当前场景路径找不到 UI 摄像机 路径 = {UI_CameraPath} 请检查");
                }
            }
        }
        private bool IsInArea(Vector2 screenPoint)
        {
            return RectTransformUtility.RectangleContainsScreenPoint(checkArea.rectTransform, screenPoint,UICamera);
        }
        public void OnBeginDrag(PointerEventData eventData)
        {
            lastMousePosition = eventData.position;
            beginEvent?.Invoke(copyItem, data);
        }
        public void OnDrag(PointerEventData eventData)
        {
            if (copyItem != null)
            {
                Vector2 mousePosition = eventData.position;
#if UNITY_ANDROID && !UNITY_EDITOR
                mousePosition = Input.GetTouch(0).position;
#endif
                Vector2 delta = mousePosition - lastMousePosition;
                ((RectTransform)transform).anchoredPosition += delta;
                lastMousePosition = mousePosition;
                if (IsInArea(mousePosition))
                {
                    if(!inEnter)
                    {
                        inEvent?.Invoke();
                        inEnter = true;
                    }
                }
                else
                {
                    if (inEnter)
                    {
                        outEvent?.Invoke();
                        inEnter = false;
                    }
                }
            }
        }
        public void OnEndDrag(PointerEventData eventData)
        {
            if (IsInArea(eventData.position))
            {
                endInAreaCallback?.Invoke(data);
            }
            inEnter = false;
            endCallback?.Invoke(data);
            outEvent?.Invoke();
        }
    }
}