wpf - 从另一个线程更快地刷新 TextBlock

Question

我确实有一个 WPF 应用程序实时显示数据(从另一个线程计算)。但是我的 UI 组件(这里是 TextBlock)更新非常缓慢。
我使用传统的数据绑定(bind) PropertyChanged通知。
xml:

<TextBlock
          Foreground="DarkGray"
          Text="{Binding Path=ContactSurface, StringFormat='{}{0:0.00} cm²'}"/>

代码隐藏(不，这不是 MVVM，真丢脸):

private double _contactSurface;
    public double ContactSurface
    {
        get { return _contactSurface; }
        set { _contactSurface = value; RaisePropertyChanged("ContactSurface"); }
    }

    public void Compute() // external thread about 10 Hz
    {
        ContactSurface = (double)nbSensorsNotNulls * DataSource.SensorSurface * 0.01;

        Dispatcher.BeginInvoke(System.Windows.Threading.DispatcherPriority.Render, new Action(() => { })); // does not change a thing
        //Dispatcher.Invoke(System.Windows.Threading.DispatcherPriority.Render, new Action(() => { })); // crash : Cannot perform this operation while dispatcher processing is suspended.

        //UpdateLayout(); // crash : The calling thread can not access this object because a different thread owns it
        //InvalidateVisual(); // crash : The calling thread can not access this object because a different thread owns it

    }

我尝试了一些我在 Compute() 结尾时在网络上找到的东西非常平均的结果细节

Answer 1

如果您在另一个线程中执行一些耗时的工作，那么您 必须将另一个线程的结果与 UI 线程同步。同步两个线程(新线程和UI线程)，需要使用 Dispatcher .

As MSDN says:

Only one thread can modify the UI thread. But how do background threads interact with the user? A background thread can ask the UI thread to perform an operation on its behalf. It does this by registering a work item with the Dispatcher of the UI thread. The Dispatcher class provides two methods for registering work items: Invoke and BeginInvoke. Both methods schedule a delegate for execution. Invoke is a synchronous call – that is, it doesn’t return until the UI thread actually finishes executing the delegate. BeginInvoke is asynchronous and returns immediately.

例如:

Task.Run(()=> {
   var result = (double)nbSensorsNotNulls * DataSource.SensorSurface * 0.01;
   Thread.Sleep(5000);//imitate time consuming work
   Dispatcher.BeginInvoke(System.Windows.Threading.DispatcherPriority.Render,
            new Action(() => { 
                            ContactSurface=result;}));
});

在上面的示例中，我们创建了一个新线程( Task.Run(...))并将新线程的结果与 UI 线程( Dispatcher.BeginInvoke(...))同步