WPF C#-计时器倒计时

如何在用WPF C#编写的代码中实现以下内容

我有一个ElementFlow控件，我在其中实现了一个SelectionChanged事件，该事件（根据定义）在控件的项选择发生更改时触发一个特定事件

我希望它做的是：

启动计时器

如果计时器达到2秒，则启动一个消息框，例如说“你好”

如果选择在计时器达到2秒之前更改，则应重置计时器并重新启动

这是为了确保仅当选择在2秒内未更改时，才会启动冗长的操作，但我不熟悉WPF的Dispatchermer功能，因为我更了解Windows窗体的正常计时器

谢谢

试试这个：

private int timerTickCount = 0;
private bool hasSelectionChanged = false;
private DispatcherTimer timer;

在构造函数或相关方法中：

timer = new DispatcherTimer();
timer.Interval = new TimeSpan(0, 0, 1); // will 'tick' once every second
timer.Tick += new EventHandler(Timer_Tick);
timer.Start();

然后是一个事件处理程序：

private void Timer_Tick(object sender, EventArgs e)
{
    DispatcherTimer timer = (DispatcherTimer)sender;
    if (++timerTickCount == 2)
    {
        if (hasSelectionChanged) timer.Stop();
        else MessageBox.Show("Hi there");
    }
}

最后，要实现这一点，您只需在选择已根据您的

SelectionChanged

事件更改时设置

hasSelectionChanged

变量。

尝试以下操作：

private int timerTickCount = 0;
private bool hasSelectionChanged = false;
private DispatcherTimer timer;

在构造函数或相关方法中：

timer = new DispatcherTimer();
timer.Interval = new TimeSpan(0, 0, 1); // will 'tick' once every second
timer.Tick += new EventHandler(Timer_Tick);
timer.Start();

然后是一个事件处理程序：

private void Timer_Tick(object sender, EventArgs e)
{
    DispatcherTimer timer = (DispatcherTimer)sender;
    if (++timerTickCount == 2)
    {
        if (hasSelectionChanged) timer.Stop();
        else MessageBox.Show("Hi there");
    }
}

---

最后，为了实现这一点，当选择根据

SelectionChanged

事件发生更改时，只需设置

hasSelectionChanged

变量。

看这里是如何使用dispatheriter的代码，您可以在其中添加自己的逻辑。那要看你了

 private void ListBox_SelectionChanged_1(object sender, SelectionChangedEventArgs e)
    {
        DispatcherTimer timer = new DispatcherTimer();
        timer.Interval = TimeSpan.FromMilliseconds(2000);
        timer.Tick += timer_Tick;
        timer.Start();

    }

    void  timer_Tick(object sender, object e)
    {
       // show your message here..
    }

---

下面是如何使用dispatheriter的代码，您可以在其中添加自己的逻辑。那要看你了

 private void ListBox_SelectionChanged_1(object sender, SelectionChangedEventArgs e)
    {
        DispatcherTimer timer = new DispatcherTimer();
        timer.Interval = TimeSpan.FromMilliseconds(2000);
        timer.Tick += timer_Tick;
        timer.Start();

    }

    void  timer_Tick(object sender, object e)
    {
       // show your message here..
    }

---

要使用Dispatcher，请执行以下操作：

    private DispatcherTimer _timer;
    public void StartTimer()
    {
        if (_timer == null)
        {
            _timer = new DispatcherTimer();
            _timer.Tick += _timer_Tick;
        }

        _timer.Interval = TimeSpan.FromSeconds(2);
        _timer.Start();
    }

    void _timer_Tick(object sender, EventArgs e)
    {
        MessageBox.Show("Hi there");
        _timer.Stop();
    }

    void SelectionChangedEvent()
    {
        StartTimer();
    }

---

要使用Dispatcher，请执行以下操作：

    private DispatcherTimer _timer;
    public void StartTimer()
    {
        if (_timer == null)
        {
            _timer = new DispatcherTimer();
            _timer.Tick += _timer_Tick;
        }

        _timer.Interval = TimeSpan.FromSeconds(2);
        _timer.Start();
    }

    void _timer_Tick(object sender, EventArgs e)
    {
        MessageBox.Show("Hi there");
        _timer.Stop();
    }

    void SelectionChangedEvent()
    {
        StartTimer();
    }

---

我已经计算出了完整的代码，如下所示：

DispatcherTimer _timer;

public MainWindow()
{
    _myTimer = new DispatcherTimer();
    _myTimer.Tick += MyTimerTick;
    _myTimer.Interval = new TimeSpan(0,0,0,1);
}

private void ElementFlowSelectionChanged(object sender, SelectionChangedEventArgs e)
{
    _counter = 0;
    _myTimer.Stop();
    _myTimer.Interval = new TimeSpan(0, 0, 0, 1);
    _myTimer.Start();
}

private int _counter;
public int Counter
{
    get { return _counter; }
    set
        {
            _counter = value;
            OnPropertyChanged("Counter");
        }
}
private void MyTimerTick(object sender, EventArgs e)
{
    Counter++;
    if (Counter == 2)
    {
        _myTimer.Stop();
        MessageBox.Show(“Reached the 2 second countdown”);
    }
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
    PropertyChangedEventHandler e = PropertyChanged;
    if (e != null)
        {
            e(this, new PropertyChangedEventArgs(propertyName));
}
}

---

我已经计算出了完整的代码，如下所示：

DispatcherTimer _timer;

public MainWindow()
{
    _myTimer = new DispatcherTimer();
    _myTimer.Tick += MyTimerTick;
    _myTimer.Interval = new TimeSpan(0,0,0,1);
}

private void ElementFlowSelectionChanged(object sender, SelectionChangedEventArgs e)
{
    _counter = 0;
    _myTimer.Stop();
    _myTimer.Interval = new TimeSpan(0, 0, 0, 1);
    _myTimer.Start();
}

private int _counter;
public int Counter
{
    get { return _counter; }
    set
        {
            _counter = value;
            OnPropertyChanged("Counter");
        }
}
private void MyTimerTick(object sender, EventArgs e)
{
    Counter++;
    if (Counter == 2)
    {
        _myTimer.Stop();
        MessageBox.Show(“Reached the 2 second countdown”);
    }
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
    PropertyChangedEventHandler e = PropertyChanged;
    if (e != null)
        {
            e(this, new PropertyChangedEventArgs(propertyName));
}
}