WPF UserControl.Loaded event does not trigger

问题

In my program, when I hover over (MouseEnter event) a certain UserControl (here I use TransportOrderLineUserControl) a TransportOrderLineDetailView should be shown.

The TransportOrderLineDetailView should be placed at the bottom right of my screen. For this I need to know the ActualWidth & ActualHeight for a correct placement. Because those 2 properties need to have a value different than 0 I execute this code with the DetailView.Loaded event.

I use the exact same way for two other objects. There it works but not for the TransportOrderLineDetailView.

Code where the view is generated:

TransportOrderLineDetailView tolDetailView = new TransportOrderLineDetailView(new TransportOrderLineDetailViewModel(transportOrderLine)); 
window.DetailContent = tolView; 
tolView.Loaded += SetDetailViewOnUI;

Code-behind view:

public TransportOrderLineDetailView(TransportOrderLineDetailViewModel detailViewModel)
    {
        InitializeComponent();
        DataContext = detailViewModel;
    }

Method SetDetailViewOnUI:

 private void SetDetailPanelOnUI(object sender, EventArgs e)
    {
        Canvas.SetLeft(window.DetailContentPresenter,
                                   window.grid_Root.ActualWidth - window.DetailContentPresenter.ActualWidth);
        Canvas.SetTop(window.DetailContentPresenter,
                      window.grid_Root.ActualHeight - window.DetailContentPresenter.ActualHeight);
    }

Example where it works well:

DriverDetailView driverDetailView = new DriverDetailView(new DriverDetailViewModel(driver));
window.DetailContent = driverDetailView;
driverDetailView.Loaded += SetDetailPanelOnUI;

More information

window.DetailContent:

private UserControl detailContent;

public UserControl DetailContent
{
    get { return this.detailContent; }
    set
    {
        this.detailContent = value;
        OnPropertyChanged("DetailContent");
    }
}

DetailContentPresenter:

 <Canvas Grid.RowSpan="2" x:Name="canvas_Popup_DetailView">
     <ContentPresenter Content="{Binding DetailContent}" x:Name="detailContentPresenter"/>
 </Canvas>

A test where the loaded event also is not triggered:

 public TransportOrderLineDetailView(TransportOrderLineDetailViewModel detailViewModel)
    {
        InitializeComponent();

        DataContext = detailViewModel;
        this.Loaded += test; //Test here
    }

    private void test(object sender, System.Windows.RoutedEventArgs e)
    {
// method never executed
    }

回答1:

Found the solution. There was an error which was not thrown.

How I did find it was going in Visual Studio to Debug -> Exceptions -> Tick the possible exceptions.

Hope this will help other people having trouble with the same stuff. :)

来源：https://stackoverflow.com/questions/21858464/wpf-usercontrol-loaded-event-does-not-trigger

标签

wpf

mvvm

loaded