C# 在 Windows 应用商店应用中重置倒数计时器 - 调度程序计时器

我是general_编程的C#newbie_and，Ι正在尝试构建一个带有倒数计时器的数学测验应用程序。

每次用户单击开始按钮时，我都会生成一个方程式，并给他最多 60 秒的回答时间。用户回答 - 无论他的答案是错还是对，都不会matter_，他/她可以再次单击新方程式。因此，我希望每次向用户显示新的随机方程时，计时器都会重置。到目前为止，我只设法在 60 秒的时间跨度过去时重置它，但即使这样也无法正常工作，有时它会显示 59 或 58 秒而不是 60 秒。

到目前为止，阅读其他问题对我没有多大帮助，计时器让我感到困惑。我也接受使我的代码更简单、更优雅的建议。

这是我的代码：

EquationView.xaml.cs

public sealed partial class EquationView : Page
    {
        DispatcherTimer timer = new DispatcherTimer();
        int tick = 60;
        int result;
        public EquationView()
        {
            this.NavigationCacheMode = NavigationCacheMode.Enabled;
            this.InitializeComponent();
        }
        private void startButton_Click(object sender, RoutedEventArgs e)
        {
            // Once clicked then disabled
            startButton.IsEnabled = false;
            // Enable buttons required for answering 
            resultTextBox.IsEnabled = true;
            submitButton.IsEnabled = true;
            var viewModel = App.equation.GenerateEquation();
            this.DataContext = viewModel;
            result = App.equation.GetResult(viewModel);
            timer.Interval = new TimeSpan(0, 0, 0, 1);
            //timer.Tick += new EventHandler(timer_Tick);
            timer.Tick += timer_Tick;
            timer.Start();
            DateTime startTime = DateTime.Now;
            // Reset message label
            if (message.Text.Length > 0)
            {
                message.Text = "";
            }
            // Reset result text box
            if (resultTextBox.Text.Length > 0)
            {
                resultTextBox.Text = "";
            }
        }
        private void timer_Tick(object sender, object e)
        {
            Countdown.Text = tick + " second(s) ";
            if (tick > 0)
                tick--;
            else
            {
                Countdown.Text = "Times Up";
                timer.Stop();
                submitButton.IsEnabled = false;
                resultTextBox.IsEnabled = false;
                startButton.IsEnabled = true;
                tick = 60;
            }
        }
        private void submitButton_Click(object sender, RoutedEventArgs e)
        {
            timer.Stop();
            submitButton.IsEnabled = false;
            resultTextBox.IsEnabled = false;
            if (System.Text.RegularExpressions.Regex.IsMatch(resultTextBox.Text, "[^0-9]"))
            {
                MessageDialog msgDialog = new MessageDialog("Please enter only numbers.");
                msgDialog.ShowAsync();
                resultTextBox.Text.Remove(resultTextBox.Text.Length - 1);
                //Reset buttons to answer again
                submitButton.IsEnabled = true;
                resultTextBox.IsEnabled = true;
                timer.Start();
            }
            else
            {
                try
                {
                    int userinput = Int32.Parse(resultTextBox.Text);
                    if (userinput == result)
                    {
                        message.Text = "Bingo!";
                        App.player.UpdateScore();
                        startButton.IsEnabled = true;
                    }
                    else
                    {
                        message.Text = "Wrong, sorry...";  
                        startButton.IsEnabled = true;
                    }
                }
                catch (Exception ex)
                {
                    MessageDialog msgDialog = new MessageDialog(ex.Message);
                    msgDialog.ShowAsync();
                    submitButton.IsEnabled = true;
                    resultTextBox.IsEnabled = true;
                    timer.Start();
                }

            }
        }

    static readonly TimeSpan duration = TimeSpan.FromSeconds(60);
    System.Diagnostics.Stopwatch sw;
    private void startButton_Click(object sender, RoutedEventArgs e)
    {
        // Once clicked then disabled
        startButton.IsEnabled = false;
        // Enable buttons required for answering 
        resultTextBox.IsEnabled = true;
        submitButton.IsEnabled = true;
        var viewModel = App.equation.GenerateEquation();
        this.DataContext = viewModel;
        result = App.equation.GetResult(viewModel);
        sw = System.Diagnostics.Stopwatch.StartNew();
        timer.Interval = new TimeSpan(0, 0, 0, 1);
        timer.Tick += timer_Tick;
        timer.Start();
        // Reset message label
        if (message.Text.Length > 0)
        {
            message.Text = "";
        }
        // Reset result text box
        if (resultTextBox.Text.Length > 0)
        {
            resultTextBox.Text = "";
        }
    }
    private void timer_Tick(object sender, object e)
    {
        if (sw.Elapsed < duration)
        {
            Countdown.Text = (int)(duration - sw.Elapsed).TotalSeconds + " second(s) ";
        }
        else
        {
            Countdown.Text = "Times Up";
            timer.Stop();
            submitButton.IsEnabled = false;
            resultTextBox.IsEnabled = false;
            startButton.IsEnabled = true;
        }
    }