Creating a Window.Title Attached Property

Question

I have a Window shell that is basically:

<Window>
    <ContentPresenter Content="{Binding}" />
</Window>

Injected into the ContentPresenter at run-time are UserControls. What I want to be able to do is write:

<UserControl Window.Title="The title for my window">
[...]
</UserControl>

So that the Window title is updated using the UserControl Window.Title property.

I have a feeling this can be achieved using attached properties. Can anyone start me off in the right direction?

Daniel

Answer 1

public class MyUserControl : UserControl
{
   public static readonly DependencyProperty WindowTitleProperty = DependencyProperty.RegisterAttached("WindowTitleProperty",
                typeof(string), typeof(UserControl),
                new FrameworkPropertyMetadata(null, WindowTitlePropertyChanged));

        public static string GetWindowTitle(DependencyObject element)
        {
            return (string) element.GetValue(WindowTitleProperty);
        }

        public static void SetWindowTitle(DependencyObject element, string value)
        {
            element.SetValue(WindowTitleProperty, value);
        }

        private static void WindowTitlePropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
                    Application.Current.MainWindow.Title = e.NewValue;
        }
}

<UserControl namespace:MyUserControl.WindowTitle="The title for my window">
[...]
</UserControl>

Answer 2

I ended up using the following:

public static class WindowTitleBehavior
{
    public static readonly DependencyProperty WindowTitleProperty = DependencyProperty.RegisterAttached(
        "WindowTitleProperty", typeof(string), typeof(UserControl),
                 new FrameworkPropertyMetadata(null, WindowTitlePropertyChanged));

    public static string GetWindowTitle(DependencyObject element)
    {
        return (string)element.GetValue(WindowTitleProperty);
    }

    public static void SetWindowTitle(DependencyObject element, string value)
    {
        element.SetValue(WindowTitleProperty, value);
    }

    private static void WindowTitlePropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        UserControl control = d as UserControl;
        if (!control.IsLoaded)
        {
            control.Loaded += new RoutedEventHandler(setTitle);
        }
        setTitle(control);
    }

    private static void setTitle(object sender, RoutedEventArgs e)
    {
        UserControl control = sender as UserControl;
        setTitle(control);
        control.Loaded -= new RoutedEventHandler(setTitle);
    }

    private static void setTitle(UserControl c)
    {
        Window parent = UIHelper.FindAncestor<Window>(c);
        if (parent != null)
        {
            parent.Title = (string)WindowTitleBehavior.GetWindowTitle(c);
        }
    }
}

Which makes use of Philipp Sumi's code snippet to find the first ancestor Window: http://www.hardcodet.net/2008/02/find-wpf-parent

In my views I can now do:

<UserControl Behaviors:WindowTitleBehavior.WindowTitle="My Window Title">

And it sets the title of the containing Window.