Attached behaviors for Windows 8 Metro Style XAML

Regular readers of my blog know that there are some recurring themes: MVVM, maps and behaviors. I am a big fan of using behaviors ever since I learned how to use this rooting trough the sources of MVVMLight. When I saw the BUILD videos I was elated. I saw a great merger of the best things of Windows and  Windows Phone 7 styles and I knew I was going to get on board too. Five months later, I found myself being an MVP and on the Microsoft Campus of all places, and got a pretty unpleasant surprise: a lady presenting the new Expression Blend version said there would be no behaviors in Windows 8 Metro Style XAML. I was quite disappointed at the time. I still think it’s is quite an omission, but then again, when it’s not your deadline it’s always easy to criticize others.

And then for some reason, this week, I remembered a single line from a presentation by Laurent Bugnion on the 2012 Microsoft Techdays in The Hague. “You can’t use behaviors but you can use attached dependency properties”. It kept reverbing trough my brain for a few moments.

“Use the Force, Luke” ;-)

And the result is this. It’s crude, it’s clumsy, it has no Blend support, but it works, more or less – I have been able to port my DragFlickBehavior to Windows 8 and it bloody works, too. This blog post will be split in two parts: in this part, I will show how to make a behavior in Windows 8 XAML in general, and in a next one I will specifically show the DragFlickBehavior itself.

First of all, the behavior class itself:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using Windows.UI.Xaml;

namespace WinRtBehaviors

{

  public abstract class Behavior : DependencyObject

  {

    private FrameworkElement associatedObject;

    public FrameworkElement AssociatedObject

    {

      get

      {

        return associatedObject;

      }

      set

      {

        if (associatedObject != null)

        {

          OnDetaching();

        }

        associatedObject = value;

        if (associatedObject != null)

        {

          OnAttached();

        }

      }

    }

Read more: .NET by example

QR: 

Posted via email from Jasper-net