通过单击按钮停止 DispatcherTimer

Question

当我点击停止按钮时，我的计时器仍在倒计时，即使我告诉它停止。

我目前的相关代码：

我在这里命名计时器，因为我还需要访问它们以获得停止/启动所有按钮。

namespace Row_Interface
{
    public partial class MainWindow : Window
    {
        //Declare the timers here, so the stop all button can access them as well
        DispatcherTimer motorTimer_1 = new DispatcherTimer();
        TimeSpan motorCycleTime_1 = TimeSpan.FromSeconds(0);

当我点击 on 按钮时，IndividualTestStart 方法被调用并传递了相关参数：

public void motorOnBtn_1_Click(object sender, RoutedEventArgs e)
        {
            IndividualTestStart(motorOnBtn_1, motorOffBtn_1, motorTimer_1, motorCycleTime_1, timeUntilmotorCycle_1, motorTestCycles_1);
        }

当我单击关闭按钮时，我想停止该计时器，以便循环永远不会结束：

        private void motorOffBtn_1_Click(object sender, RoutedEventArgs e)
        {
            motorTimer_1.Stop();
            motorOnBtn_1.IsEnabled = true; //Enables the start test button
            motorOffBtn_1.IsEnabled = false; //Disables the stop test button

        }

当我单击开始时调用它。我最终会有类似的停止按钮，但我一步一步地采取措施：

private void IndividualTestStart(Button startButton, Button stopButton, DispatcherTimer dispatcherTimer, TimeSpan timeSpan, TextBox timeRemaining, TextBox cycleCount)
        {
            stopButton.IsEnabled = true; //Enables the stop button

            //Set the time to run. This will be set from the database eventually.
            timeSpan = TimeSpan.FromSeconds(10);

            //Set up the new timer. Updated every second.
            dispatcherTimer = new DispatcherTimer(new TimeSpan(0, 0, 1), DispatcherPriority.Normal, delegate
            {
                timeRemaining.Text = timeSpan.ToString("c"); //Sets the text in the textbox to the time remaining in the timer
                startButton.IsEnabled = false; //Disables the start test button once the test is started
                if (timeSpan == TimeSpan.Zero) //Checks to seee if the time has run out
                {
                    dispatcherTimer.Stop(); //Stops the timer once the time has run out
                    startButton.IsEnabled = true; //Enables the start test button
                    int initialCycleCount = 0;
                    initialCycleCount++;
                    cycleCount.Text = initialCycleCount.ToString();
                    stopButton.IsEnabled = false;//Disables the stop button

                }
                timeSpan = timeSpan.Add(TimeSpan.FromSeconds(-1)); //Subtracts one second each time the timer "ticks"
            }, Application.Current.Dispatcher);  //runs within the UI thread

            dispatcherTimer.Start(); //Starts the timer 
        }
}

当我单击停止按钮时，我希望文本框中的计时器停止倒计时。但是，它只是不断滴答作响。当我单击停止时，开始按钮被重新启用，所以我知道它正在触发事件处理程序中的代码。但它并没有停止计时器。

现在没有开始新的计时器。 新代码：

        public void motorOnBtn_1_Click(object sender, RoutedEventArgs e)
        {
            IndividualTestStart(motorOnBtn_1, motorOffBtn_1, motorTimer_1, motorCycleTime_1, timeUntilmotorCycle_1, motorTestCycles_1);
        }

        private void IndividualTestStart(Button startButton, Button stopButton, DispatcherTimer dispatcherTimer, TimeSpan timeSpan, TextBox timeRemaining, TextBox cycleCount)
        {
            stopButton.IsEnabled = true; //Enables the stop button

            //Set the time to run. This will be set from the database eventually.
            timeSpan = TimeSpan.FromSeconds(10);

            {
                timeRemaining.Text = timeSpan.ToString("c"); //Sets the text in the textbox to the time remaining in the timer
                startButton.IsEnabled = false; //Disables the start test button once the test is started
                if (timeSpan == TimeSpan.Zero) //Checks to seee if the time has run out
                {
                    dispatcherTimer.Stop(); //Stops the timer once the time has run out
                    startButton.IsEnabled = true; //Enables the start test button
                    int initialCycleCount = 0;
                    initialCycleCount++;
                    cycleCount.Text = initialCycleCount.ToString();
                    stopButton.IsEnabled = false;//Disables the stop button

                }
                timeSpan = timeSpan.Add(TimeSpan.FromSeconds(-1)); //Subtracts one second each time the timer "ticks"
            };  //runs within the UI thread

            dispatcherTimer.Start(); //Starts the timer 
        }

Answer 1

您的代码中的问题是您使用不执行任何操作的DispatcherTimer 初始化motorTimer_1，然后将motorTimer_1 作为dispatcherTimer 参数传入，然后替换参数的值使用新创建的不同DispatcherTimer。

新计时器工作正常，但是当您在 motorTimer_1 上调用 stop 时，什么也没有发生，因为那不是正在运行的计时器。您可以简单地将新的DispatcherTimer 直接分配给IndividualTestStart() 中的motorTimer_1，但是您在参数化IndividualTestStart() 中的所有内容时遇到了很大的麻烦，因此它可以与不同的DispatcherTimers 一起使用。

相反，我们将这样做：没有理由传递DispatcherTimer。 IndividualTestStart() 必须创建 DispatcherTimer 才能对其进行初始化。好的，让我们开始吧。它将创建一个新的并返回它。

private DispatcherTimer IndividualTestStart(Button startButton, Button stopButton, 
    TimeSpan timeSpan, TextBox timeRemaining, TextBox cycleCount)
{
    stopButton.IsEnabled = true; //Enables the stop button

    //Set the time to run. This will be set from the database eventually.
    timeSpan = TimeSpan.FromSeconds(10);

    //  Set up the new timer. Updated every second.
    var dispatcherTimer = new DispatcherTimer(new TimeSpan(0, 0, 1), DispatcherPriority.Normal, delegate
    {
        timeRemaining.Text = timeSpan.ToString("c"); //Sets the text in the textbox to the time remaining in the timer
        startButton.IsEnabled = false; //Disables the start test button once the test is started
        if (timeSpan == TimeSpan.Zero) //Checks to seee if the time has run out
        {
            dispatcherTimer.Stop(); //Stops the timer once the time has run out
            startButton.IsEnabled = true; //Enables the start test button
            int initialCycleCount = 0;
            initialCycleCount++;
            cycleCount.Text = initialCycleCount.ToString();
            stopButton.IsEnabled = false;//Disables the stop button

        }
        timeSpan = timeSpan.Add(TimeSpan.FromSeconds(-1)); //Subtracts one second each time the timer "ticks"
    }, Application.Current.Dispatcher);  //runs within the UI thread

    dispatcherTimer.Start(); //Starts the timer 

    return dispatcherTimer;
}

public void motorOnBtn_1_Click(object sender, RoutedEventArgs e)
{
    if (motorTimer_1 == null)
    {
        //  Create/initialize a new timer and assign it to motorTimer_1
        motorTimer_1 = IndividualTestStart(motorOnBtn_1, motorOffBtn_1, 
            motorCycleTime_1, timeUntilmotorCycle_1, motorTestCycles_1);
    }
    else
    {
        //  It's already there, just start it. 
        motorTimer_1.Start();
    }
}

由于这是 WPF，您需要编写一个视图模型类 TimerThing（想一个更好的名称），它拥有一个 DispatcherTimer、两个启动和停止它的命令，以及一个指示它是否为跑步与否。 IndividualTestStart() 应该是该类的方法。父视图模型将有一个ObservableCollection<TimerThing>，其中包含任意数量的TimerThings，它将显示在带有一个ItemTemplate 的ItemsControl 中，该ItemTemplate 创建绑定到Start 和Stop 命令的按钮。上面的代码看起来会很不一样，因为没有任何 C# 代码对按钮有任何了解：相反，项目模板 XAML 中的按钮将通过绑定启用/禁用。