Another implementation of WPF Event to Command (with problems)

Question

I am looking at various implementations of hooking a ICommand up to a control\'s event. So for instance the GotFocus of a TextBox should call a GotFocusCommand in my View Mo

Answer 1

There are a couple of ways you could approach this, either using an Attached Property or inheriting from Button and adding your own DependencyProperty that contains a list of EventToCommand objects, and when you add to that collection you wire up the event to command. If this seems confusing, I can try to whip up some examples.

C#

    public class EventedButton : Button
{
    public static DependencyProperty EventCommandsProperty
        = DependencyProperty.Register("EventCommands", typeof(EventToCommandCollection), typeof(EventedButton), new PropertyMetadata(null));


    public EventToCommandCollection EventCommands
    {
        get
        {
            return this.GetValue(EventCommandsProperty) as EventToCommandCollection;
        }
        set
        {
            this.SetValue(EventCommandsProperty, value);
        }
    }

    public EventedButton()
    {
        this.EventCommands = new EventToCommandCollection(this);
    }
}

Xaml:

Inside of EventToCommandCollection, you would attach/detach to the Event you wanted when items are added to the collection.

UPDATE: Attached Property

Here is some code to do the collection as an attached property:

C#

        public static DependencyProperty CommandsProperty =
        DependencyProperty.RegisterAttached(
        "Commands",
        typeof(ICollection),
        typeof(DependencyObject),
        new PropertyMetadata(null, OnCommandsChanged));


    private static void OnCommandsChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        // Attach/Detach event handlers
    }

    public static void SetCommands(DependencyObject element, ICollection value)
    {
        element.SetValue(CommandsProperty, value);
    }

    public static ICollection GetCommands(DependencyObject element)
    {
        return (ICollection)element.GetValue(CommandsProperty);
    }

Xaml: