Window.InputBindings with a bound collection

Question

I can't find anything that looks like this online. I am looking for a way to create a collection of Keybindings in the code (with a Keybinding ViewModel), and then bind the collection to the view, instead of listing out every binding manually in Xaml.

I would expect it to look something like this

<Window.InputBindings ItemsSource="{Binding Path=KeybindingList}" />

and then in the code, have a List. Is such an approach possible? Where would I start?

Answer 1

You can create an attached property, listen to its changes and modify the InputBindings collection of the associated window.

An example:

// Snippet warning: This may be bad code, do not copy.
public static class AttachedProperties
{
    public static readonly DependencyProperty InputBindingsSourceProperty =
        DependencyProperty.RegisterAttached
            (
                "InputBindingsSource",
                typeof(IEnumerable),
                typeof(AttachedProperties),
                new UIPropertyMetadata(null, InputBindingsSource_Changed)
            );
    public static IEnumerable GetInputBindingsSource(DependencyObject obj)
    {
        return (IEnumerable)obj.GetValue(InputBindingsSourceProperty);
    }
    public static void SetInputBindingsSource(DependencyObject obj, IEnumerable value)
    {
        obj.SetValue(InputBindingsSourceProperty, value);
    }

    private static void InputBindingsSource_Changed(DependencyObject obj, DependencyPropertyChangedEventArgs e)
    {
        var uiElement = obj as UIElement;
        if (uiElement == null)
            throw new Exception(String.Format("Object of type '{0}' does not support InputBindings", obj.GetType()));

        uiElement.InputBindings.Clear();
        if (e.NewValue == null)
            return;

        var bindings = (IEnumerable)e.NewValue;
        foreach (var binding in bindings.Cast<InputBinding>())
            uiElement.InputBindings.Add(binding);
    }
}

This can be used on any UIElement:

<TextBox ext:AttachedProperties.InputBindingsSource="{Binding InputBindingsList}" />

If you want it to be very fancy you can type-check for INotifyCollectionChanged and update the InputBindings if the collection changes but you will need to unsubscribe from the old collection and such so you need to be more careful with that.