c# - 确定的日期时间还剩 4 分钟时启用按钮

Question

我正在使用 MvvmLight 开发 WPF 应用程序。我想在结算时间还剩 4 分钟时启用按钮。它应该在 UI 中自动启用。我应该使用线程来持续跟踪 CurrentUTCtime 和 mytime 的差异吗？如果是，那么如何在这段代码中使用线程呢？这是我的代码。

Datetime mytime = new DateTime(DateTime.Now.Year,DateTime.Now.Month,DateTime.Now.Day,22,0,0)

public RelayCommand Open
{
    get 
    { 
        return Open?? (_open= new RelayCommand(ExecuteOpen, CanExecuteOpen)); 
    }

    private void ExecuteOpen()
    {
        _navigation.NavigationToSetBetsDialogue();
    }

    private bool CanExecuteOpen()
    {
        double? remainingMinutes = null;

        DateTime CurrentUTCtime = DateTime.UtcNow;
        remainingMinutes = mytime .Subtract(CurrentUTCtime).TotalMinutes;

        if (remainingMinutes <= 4)
        {
            return true;
        }
        else
        {
            return false;
        }
    }
}

Answer 1

尝试使用 DispatcherTimer:

        private DispatcherTimer _Timer = new DispatcherTimer();
        private bool _CanExecute;

        private void StartTimer()
        {
            var mytime = new DateTime( DateTime.Now.Year, DateTime.Now.Month, DateTime.Now.Day, 22, 0, 0 );

            var interval = DateTime.UtcNow - mytime - TimeSpan.FromMinutes( 4 );
            _Timer.Interval = interval;
            _Timer.Tick += Timer_Tick;
        }

        private void Timer_Tick( object sender, EventArgs e )
        {
            _Timer.Tick -= Timer_Tick;
            _CanExecute = true;
            CommandManager.InvalidateRequerySuggested();
        }

        public ICommand Open
        {
            get { return new RelayCommand( ExecuteOpen, () => _CanExecute ); }
        }