Unity中，在按下、滑动、抬起时发出相应事件，用于输入控制

说明：MyInput需挂在一个全屏Img（设置为透明）上。

MyInput.cs

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

public class MyInput : MonoBehaviour, IPointerDownHandler, IDragHandler, IPointerUpHandler
{
    private const int DefaultId = -100;
    private int _curId;
    private Vector2 _centerPos;

    // 位置
    public event Action<Vector2> PointerDownEvent;
    // 朝向
    public event Action<Vector2> PointerDragEvent;
    // 位置
    public event Action<Vector2> PointerUpEvent;

    public void Init()
    {
        ResetId();
    }

    public void MyDestroy()
    {

    }

    public void OnPointerDown(PointerEventData eventData)
    {
        if (_curId == DefaultId)
        {
            _curId = eventData.pointerId;

            _centerPos = eventData.position;
            PointerDownEvent?.Invoke(_centerPos);
        }
    }

    public void OnDrag(PointerEventData eventData)
    {
        if (_curId == eventData.pointerId)
        {
            var curDir = (eventData.position - _centerPos).normalized;
            PointerDragEvent?.Invoke(curDir);
        }
    }

    public void OnPointerUp(PointerEventData eventData)
    {
        if (_curId == eventData.pointerId)
        {
            ResetId();
            PointerUpEvent?.Invoke(eventData.position);
        }
    }

    private void ResetId()
    {
        _curId = DefaultId;
    }
}