How to Achieve the Application.DoEvents() Functionality in WPF?

Mock Application.DoEvents() method in WPF

In a traditional Windows Forms application, the Application.DoEvents() method allows the application to return control to the operating system to handle other UI events. However, there is no equivalent Application.DoEvents() method natively in WPF.

To solve this problem, you can create a custom DoEvents() method. Here's an example:

<code class="language-csharp">public static void DoEvents()
{
    Application.Current.Dispatcher.Invoke(DispatcherPriority.Background,
                                          new Action(delegate { }));
}</code>

This method uses the Dispatcher.Invoke() method to call an empty delegate on the background scheduler thread. This forces the scheduler to handle any pending tasks, effectively handing control back to the operating system.

Consider the following code example:

<code class="language-csharp">public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }

    private void myButton_Click(object sender, RoutedEventArgs e)
    {
        Console.WriteLine($"缩放比例：{myScaleTransform.ScaleX}，位置：{myCanvas.PointToScreen(GetMyButtonLocation())}");

        myScaleTransform.ScaleX = myScaleTransform.ScaleY = myScaleTransform.ScaleX + 1;

        DoEvents();
        // 处理任何挂起的 UI 事件以更新按钮的位置

        Console.WriteLine($"缩放比例：{myScaleTransform.ScaleX}，位置：{myCanvas.PointToScreen(GetMyButtonLocation())}");
    }

    private Point GetMyButtonLocation()
    {
        return new Point(Canvas.GetLeft(myButton), Canvas.GetTop(myButton));
    }
}</code>

By manually calling DoEvents() after updating the scale transform, the application ensures that the button's position is updated before the next Console.WriteLine() call.

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