WPF: Using controls as content

One of the fantastic new features in WPF is the way many controls can use other controls (and a lot of other things apart from what would usually be regarded as controls) as content. I wanted to try this out, and I created a little sample program. I started with a small WPF application that has a window with a ListBox control in it. Then I created the following class:

public class WowContent: StackPanel {
  public WowContent(params string[] entries) {
    Orientation = Orientation.Horizontal;

    Button button = new Button();
    button.Content = "Click!";
    Children.Add(button);
    listBox = new ListBox();
    data = new List<string>(entries);
    listBox.ItemsSource = data;
    Children.Add(listBox);
  }

  ListBox listBox;
  List<string> data;
}

This class derives from a WPF StackPanel, which is one of the container classes. In this case, the controls inside the StackPanel are just “listed”, one behind the other. The extended StackPanel I created contains a Button and a ListBox, which in turn is bound to a list of strings. Now I wanted to initialize the main ListBox on the form with a list of WowContent instances. I created the following method for this:

public void BindStuff() {
  List<WowContent> list = new List<WowContent>();
  list.Add(new WowContent("Hi", "there"));
  list.Add (new WowContent());
  list.Add (new WowContent("Another", "entry", "with", "more", "text"));
  listBox1.ItemsSource = list;
}

My first try was to call this method in the window’s constructor, after the call to InitializeControl. But I found that this is not possible for some reason, it always results in an exception thrown from the Application.Run method: Error at element '' in markup file 'Window2.xaml' : Exception has been thrown by the target of an invocation.

I guess this has something to do with the initialization process of XAML windows. I created this method instead, which made things work:

protected override void OnInitialized(EventArgs e) {
  base.OnInitialized(e);

  BindStuff();
}

The result of all this, magically, looks like this: