test/Assets/PerfectWorld/Scripts/Utility/DoubleTapButton.cs

using System;
using UnityEngine;
using UnityEngine.EventSystems;

public class DoubleTapButton : MonoBehaviour, IPointerClickHandler
{
    [SerializeField] private float doubleTapThreshold = 0.25f;

    // Subscribe bằng code: doubleTapButton.DoubleTapped += () => ...
    public event Action SingleTapped;
    public event Action DoubleTapped;

    private float _lastTapTime = -999f;
    private bool _waitingSingle;
    private int _tapCount;
    private Coroutine _singleRoutine;

    public void OnPointerClick(PointerEventData eventData)
    {
        if (eventData.button != PointerEventData.InputButton.Left) return;

        float now = Time.unscaledTime;

        if (now - _lastTapTime <= doubleTapThreshold) _tapCount++;
        else _tapCount = 1;

        _lastTapTime = now;

        if (_tapCount == 2)
        {
            _tapCount = 0;

            // huỷ single đang chờ
            _waitingSingle = false;
            if (_singleRoutine != null)
            {
                StopCoroutine(_singleRoutine);
                _singleRoutine = null;
            }

            DoubleTapped?.Invoke();
        }
        else
        {
            // chờ 1 khoảng để xem có tap lần 2 không, rồi mới fire single
            if (!_waitingSingle)
            {
                _waitingSingle = true;
                _singleRoutine = StartCoroutine(WaitThenSingle());
            }
        }
    }

    private System.Collections.IEnumerator WaitThenSingle()
    {
        float start = Time.unscaledTime;
        while (Time.unscaledTime - start < doubleTapThreshold)
        {
            if (!_waitingSingle) yield break; // đã double-tap
            yield return null;
        }

        _waitingSingle = false;
        _singleRoutine = null;
        SingleTapped?.Invoke();
    }
}