.net - WPF UserControl 的初始化事件未触发

Question

我有一个非常简单的 WPF UserControl，如下所示:

namespace MyUserControl
{
  /// <summary>
  /// Interaction logic for UserControl1.xaml
  /// </summary>
  public partial class UserControl1 : UserControl
  {
    public UserControl1()
    {
      InitializeComponent();
    }

    protected override void OnRender(DrawingContext drawingContext)
    {
      Rect rect = new Rect(RenderSize);
      drawingContext.DrawRectangle(Brushes.AliceBlue, new Pen(Brushes.Red, 1), rect);
      base.OnRender(drawingContext);
    }
  }
}

然后我在标准 WPF 窗口的 XAML 中使用它，如下所示:

<Window x:Class="WpfApplication1.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:mc="clr-namespace:MyUserControl;assembly=MyUserControl"
    Title="Window1" Height="351" Width="496">
    <Grid>
    <mc:UserControl1 Margin="0,0,0,0" Name="uControl1" Initialized="uControl1_Initialized"/>
  </Grid>
</Window>

上面的 WPF 窗口后面的代码如下所示:

private void uControl1_Initialized(object sender, EventArgs e)
{
  MessageBox.Show("Hello!");
}

不幸的是，Initialized 事件从未被触发。谁能告诉我为什么？

非常感谢!

Answer 1

MSDN doc说

This event will be raised whenever theEndInit or OnVisualParentChangedmethods are called. Calls to eithermethod could have come fromapplication code, or through theExtensible Application Markup Language(XAML) processor behavior when a XAMLpage is processed.

我可以在这里重现您的问题。我建议使用 Loaded而是在控件布局和呈现后触发的事件。如果您真的需要 Initialized事件，听从这个 MSDN Forum thread的建议并在 UserControl 的构造函数中附加一个事件处理程序调用前 InitializeComponent()像这样:

public UserControl1()
{
    this.Initialized += delegate
    {
        MessageBox.Show("Hello!");
    };
    InitializeComponent();
}

更详细的解释 Loaded对比 Initialized ，见 this blog posting .