WinRT AttachedCommands

AttachedCommands.cs

    public static class AttachedCommands
    {
        public static readonly DependencyProperty ControlTappedCommandProperty =
            DependencyProperty.RegisterAttached("ControlTappedCommand",
            typeof(ICommand), typeof(AttachedCommands),
            new PropertyMetadata(null, new PropertyChangedCallback(AttachOrRemoveUIElementTappedEvent)));

        public static ICommand GetControlTappedCommand(DependencyObject obj)
        {
            return (ICommand)obj.GetValue(ControlTappedCommandProperty);
        }

        public static void SetControlTappedCommand(DependencyObject obj, ICommand value)
        {
            obj.SetValue(ControlTappedCommandProperty, value);
        }

        public static void AttachOrRemoveUIElementTappedEvent(DependencyObject obj, DependencyPropertyChangedEventArgs args)
        {
            UIElement uiElement = obj as UIElement;
            if (uiElement != null)
            {
                ICommand cmd = (ICommand)args.NewValue;

                if (args.OldValue == null && args.NewValue != null)
                    uiElement.Tapped += ExecuteUIElementTapped;
                else if (args.OldValue != null && args.NewValue == null)
                    uiElement.Tapped -= ExecuteUIElementTapped;
            }
        }

        private static void ExecuteUIElementTapped(object sender, TappedRoutedEventArgs e)
        {
            DependencyObject obj = sender as DependencyObject;
            ICommand cmd = (ICommand)obj.GetValue(ControlTappedCommandProperty);
            if (cmd != null)
            {
                if (cmd.CanExecute(obj))
                    cmd.Execute(obj);
            }
        }
    }