winphone讓代碼等待2秒DispatcherTimer

Question

我使用visual studio 2010為Win Phone進行圖像處理。為了讓圖片顯示2秒（如幻燈片放映），下面的類被稱為

namespace photoBar
{
    public class WaitTwoSeconds
    {
        DispatcherTimer timer = new DispatcherTimer();
        public bool timeUp = false;

        // This is the method to run when the timer is raised. 
        private void TimerEventProcessor(Object myObject,
                                                EventArgs myEventArgs)
        {
            timer.Stop();
            timeUp = true;
        }

        public WaitTwoSeconds()
        {
            /* Adds the event and the event handler for the method that will 
               process the timer event to the timer. */
            timer.Tick += new EventHandler(TimerEventProcessor);

            // Sets the timer interval to 2 seconds.
            timer.Interval = new TimeSpan(0, 0, 2); // one second
            timer.Start();

            //// Runs the timer, and raises the event. 
            while (timeUp== false)
            {
                // Processes all the events in the queue.
                Application.DoEvents();
            } 
        }
    }
}

它以這種方式調用：

        WaitTwoSeconds waitTimer = new WaitTwoSeconds();
        while (!waitTimer.timeUp)
        {
        }

因為Application.DoEvents(); 聲稱為錯誤：'System.Windows.Application'不包含'DoEvents'的定義。 所以我刪除了那個代碼塊

        while (timeUp== false)
        {
            // Processes all the events in the queue.
            Application.DoEvents();
        } 

編譯並運行程序后，顯示簡歷...
我怎么能糾正這個？ 謝謝

Answer 1

使用Reactive Extensions（參考Microsoft.Phone.Reactive）可以更輕松地完成此操作：

Observable.Timer(TimeSpan.FromSeconds(2)).Subscribe(_=>{
    //code to be executed after two seconds
});

請注意，代碼不會在UI線程上執行，因此您可能需要使用Dispatcher。

Answer 2

擁抱多線程。

public class WaitTwoSeconds
{
    DispatcherTimer timer = new DispatcherTimer();
    Action _onComplete;

    // This is the method to run when the timer is raised. 
    private void TimerEventProcessor(Object myObject,
                                            EventArgs myEventArgs)
    {
        timer.Stop();
        _onComplete();
    }

    public WaitTwoSeconds(Action onComplete)
    {
        _onComplete = onComplete;
        timer.Tick += new EventHandler(TimerEventProcessor);
        timer.Interval = new TimeSpan(0, 0, 2); // one second
        timer.Start();

    }
}

在你的代碼中

private WaitTwoSeconds waitTimer;
private void SomeButtonHandlerOrSomething(
    object sender, ButtonClickedEventArgsLol e)
{    
    waitTimer = new WaitTwoSeconds(AfterTwoSeconds);
}

private void AfterTwoSeconds()
{
    // do whatever
}

這種設計並不是那么好，但它應該讓您清楚地了解多線程的工作原理。 如果你沒有做某事 ，那就不要阻止 。