Silverlight（桌面不是手机）循环问题 [英] Silverlight (Desktop not phone) Loop Question

问题描述

我有一个Silverlight桌面应用程序，它在单击按钮后启动计时器。定时器等待10秒，然后，它将重置定时器，每5秒循环一次。



如何在60秒后停止计时器？有人推荐了StopWatch，但它在Silverlight Desktop中不可用。



这是我的代码有效，但60秒后它不会停止：



谢谢！

I have a Silverlight Desktop Application which starts a timer after a button is clicked. The Timer Waits for 10 seconds, then, it will reset the timer to loop every 5 seconds.

How do I stop the timer after 60 seconds have elapsed? Someone recommended the StopWatch, but it''s not available in Silverlight Desktop.

Here is my code that works, but it does not stop after 60 seconds:

Thank you!

public void StartTimer()
        {
            System.Windows.Threading.DispatcherTimer myDispatchTimer = new System.Windows.Threading.DispatcherTimer();
            myDispatchTimer.Interval = TimeSpan.FromSeconds(10); // initial 10 second wait
            myDispatchTimer.Tick += new EventHandler(Initial_Wait);
            myDispatchTimer.Start();
        }
        void Initial_Wait(object o, EventArgs sender)
        {
            System.Windows.Threading.DispatcherTimer myDispatchTimer = new System.Windows.Threading.DispatcherTimer();
            // Stop the timer, replace the tick handler, and restart with new interval.
            myDispatchTimer.Stop();
            myDispatchTimer.Tick -= new EventHandler(Initial_Wait);
            myDispatchTimer.Interval = TimeSpan.FromSeconds(5); //every x seconds
            myDispatchTimer.Tick += new EventHandler(Each_Tick);
            myDispatchTimer.Start();
        }

        // Counter:
        int i = 0;
        // Ticker
        void Each_Tick(object o, EventArgs sender)
        {
            GetMessageDeliveryStatus(messageID, messageKey);
            textBlock1.Text = "Seconds: " + i++.ToString();
        }

推荐答案

创建一个成员变量startTime，并在StartTimer中将其设置为DateTime.Now。然后，在Initial_Wait中，从DateTime.Now中减去startTime并检查TotalSeconds。如果超过60秒，请停止计时器。或者，您可以使用计数器方法（因为您似乎部分使用您的成员变量i）。



此外，根据您提供的示例代码，你将没有一个计时器，但很多计时器会彼此并行执行。将myDispatchTimer移出函数并在类级别只放一个（这称为成员变量）。只创建一次新实例。在新实例上调用Stop（）不会阻止先前的实例运行。



编辑：这是一些例子您可以使用的代码：

Create a member variable, startTime, and set it to DateTime.Now in StartTimer. Then, in Initial_Wait, subtract startTime from DateTime.Now and check the TotalSeconds. If greater than 60 seconds, stop the timer. Alternatively, you could use a counter approach (as you appear to be partially doing with your member variable "i").

Also, based on the sample code you provided, you will not have one timer, but many which will execute alongside each other. Move myDispatchTimer out of the functions and put only one at the class level (this is called a member variable). Only create a new instance of it once. Calling Stop() on a new instance will not stop the previous instance from running.

Here''s an example of some code you could use:

private System.Windows.Threading.DispatchTimer timer = new System.Windows.Threading.DispatcherTimer();
private bool firstRun = true;
private DateTime startTime = DateTime.MinValue;

private void StartTimer()
{
    startTime = DateTime.Now;
    timer.Interval = TimeSpan.FromSeconds(10);
    timer.Tick += new EventHandler(timer_Tick);
    timer.Start();
}

void timer_Tick(object sender, EventArgs e)
{
    if (firstRun)
    {
        timer.Interval = TimeSpan.FromSeconds(5);
        firstRun = false;
    }
    if (DateTime.Now.Subtract(startTime).TotalSeconds > 60)
    {
        timer.Stop();
    }
    else
    {
        var t = new System.Threading.Thread(new System.Threading.ThreadStart(delegate()
        {
            // ...do stuff that takes a while....
        }));
        t.Start();
        // ...or do stuff that runs quickly....
    }
}

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