using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI;

public class SubScrollRect : ScrollRect
{
    //父ScrollRect对象
    private ScrollRect m_Parent;

    public enum Direction
    {
        Horizontal,
        Vertical
    }

    //滑动方向
    private Direction m_Direction = Direction.Horizontal;

    //当前操作方向
    private Direction m_BeginDragDirection = Direction.Horizontal;

    protected override void Start()
    {
        base.Start();
        //找到父对象
        Transform parent = transform.parent;
        m_Parent = parent.GetComponentInParent<ScrollRect>();

        m_Direction = this.horizontal ? Direction.Horizontal : Direction.Vertical;
    }


    public override void OnBeginDrag(PointerEventData eventData)
    {
        if (m_Parent)
        {
            m_BeginDragDirection = Mathf.Abs(eventData.delta.x) > Mathf.Abs(eventData.delta.y)
                ? Direction.Horizontal
                : Direction.Vertical;
            if (m_BeginDragDirection != m_Direction)
            {
                //当前操作方向不等于滑动方向，将事件传给父对象
                ExecuteEvents.Execute(m_Parent.gameObject, eventData, ExecuteEvents.beginDragHandler);
                return;
            }
        }

        base.OnBeginDrag(eventData);
    }

    public override void OnDrag(PointerEventData eventData)
    {
        if (m_Parent)
        {
            if (m_BeginDragDirection != m_Direction)
            {
                //当前操作方向不等于滑动方向，将事件传给父对象
                ExecuteEvents.Execute(m_Parent.gameObject, eventData, ExecuteEvents.dragHandler);
                return;
            }
        }

        base.OnDrag(eventData);
    }

    public override void OnEndDrag(PointerEventData eventData)
    {
        if (m_Parent)
        {
            if (m_BeginDragDirection != m_Direction)
            {
                //当前操作方向不等于滑动方向，将事件传给父对象
                ExecuteEvents.Execute(m_Parent.gameObject, eventData, ExecuteEvents.endDragHandler);
                return;
            }
        }

        base.OnEndDrag(eventData);
    }

    public override void OnScroll(PointerEventData data)
    {
        if (m_Parent)
        {
            if (m_BeginDragDirection != m_Direction)
            {
                //当前操作方向不等于滑动方向，将事件传给父对象
                ExecuteEvents.Execute(m_Parent.gameObject, data, ExecuteEvents.scrollHandler);
                return;
            }
        }

        base.OnScroll(data);
    }
}