TechDays WPC 2010: I’ll be there! Speaking about Silverlight, Multi-Touch and Natural User Interfaces

This year I’ll be presenting about “Silverlight, Multi-Touch and Natural User Interfaces” at the Techdays WPC 2010 conference in Milan on November, 25 2010.

The same day I’ll be also at the MVP booth, if you’re attending the conference come and say Hi! 🙂

Happy Silverlighting!

Windows Phone 7, Multi-Touch Behaviors and the Surface samples for Silverlight

I’ve just finished some experiments using the Windows Phone 7 emulator and the “Microsoft Surface Manipulations and Inertia Sample for Microsoft Silverlightin order to enable Multi-Touch gestures using Blend Behaviors:

WP7BehaviorExpression

This new implementation, now available for download in the Expression Gallery, permits to enable Multi-Touch gestures (the usual translation, rotation, zoom and inertia) on separate User Controls available in the same container.

In this way you can apply distinct Multi-Touch manipulations (inertia included) to single elements using a single code in xaml:


  <canvas>
      
          
               
          
      

      
          
             
          
      
  </canvas>

Alternatively you can use Blend inserting a reference to the project MultiTouch.Behaviors.Silverlight.WP7 and then dragging the MultiTouchManipulationBehavior from the Assets section to the  control to be touch-enabled:

Multi-Touch Behavior Blend

 

Considerations

This one has been an interesting exercise in porting code written for Silverlight to Windows Phone: I had only to create a Windows Phone 7 project and add to it the code already available for the Silverlight version and all worked well quite quickly.

Limitations

At this time the behavior works only in the fixed Portrait orientation of Windows Phone: if you change to Landscape the manipulation doesn’t work well. I’ll have to investigate further and currently I don’t have a physical device to test (I’d really love to have a device to try it :)).

Happy Silverlighting!

Windows Phone 7 Multi-Touch Behavior videos #wp7dev

Some time ago I’ve started a Codeplex project dedicated to multi-touch, available on Codeplex at http://multitouch.codeplex.com.

The goal of this project is to provide an unified interface for Silverlight, WPF and Windows Phone 7 in order to provide multi-touch support using a visual approach via the concept of Behavior available in Expression Blend.

Recently I had the honor to welcome in the project a pillar of the Silverlight community, Laurent Bugnion, who is working on the Windows Phone 7 version of the Behavior:

Laurent has just published on his blog two awesome videos to get started with this new Behavior, and has created a specific section on his site http://www.galasoft.ch/touch to announce updates and publish content.

A special thanks to Pete Blois of the Expression Blend team for his help and contributions.

Stay tuned as we’ll be posting updates very soon 🙂

Happy Silverlighting!

Slides and Code from my Silverlight 4 – MEF webcast

Here you can find the sample code and slides (in italian) from my webcast around Silverlight 4 and MEF for the local XEdotNET user group.

The samples contain the following topics:

  • Simple composition using the CompositionInitializer;
  • Multiple Exports;
  • Metadata;
  • Custom Attributes;
  • Dynamic object creation with ExportFactory;
  • Simple MVVM example using MEF;
  • MEF, MVVM and PRISM EventAggregator;
  • Dynamic XAP loading using DeploymentCatalog;
  • MEF, MVVM and Blend Sample Data.

Hope this helps and Happy Silverlighting!

Silverlight 4, MEF and MVVM: MEFModules, Dynamic XAP Loading and Navigation Applications

In the last example I’ve implemented a new “MEF Module” organized with a MVVM approach and using Prism Event Aggregator to exchange messages.

This new module could be used to partititon the application in several XAPs composed dynamically at run-time using MEF, the new DeploymentCatalog and the Navigation features available in Silverlight.

To start I’ve created a new “Silverlight Navigation Application” which produces a complete application with ready-to-use navigation and localization.

Then I’ve inserted a new “Silverlight User Control” inside the “Views” folder and named it “MEFModuleContainer“: this one is called by the navigation framework and is responsible to load dynamically the module using the MEF “DeploymentCatalog“.

This is the XAML of the container:

<StackPanel x:Name="ContentStackPanel">
    <TextBlock x:Name="HeaderText" Style="{StaticResource HeaderTextStyle}"
               Text="MEF Module container"/>
    <TextBlock x:Name="ContentText" Style="{StaticResource ContentTextStyle}"
               Text="MEF content"/>
    <ItemsControl x:Name="content"/>
</StackPanel>

Our “MEF Module” is hosted in a “ItemsControl” using the “Items” property:

public MEFModuleContainer()
{
    InitializeComponent();

    CompositionInitializer.SatisfyImports(this);

    CatalogService.AddXap("MEFModule.xap");
}

[Import]
public IDeploymentCatalogService CatalogService { get; set; }

[ImportMany(AllowRecomposition = true)]
public Lazy<UserControl>[] MEFModuleList { get; set; }

#region IPartImportsSatisfiedNotification Members

public void OnImportsSatisfied()
{
    MEFModuleList.ToList()
        .ForEach(module=>
            content.Items.Add(module.Value)
        );
}

#endregion

In order to use the DeploymentCatalog, it’s necessary to define an interface IDeploymentCatalogService (read this post by Glenn Block for more information about it):

public interface IDeploymentCatalogService
{
    void AddXap(string uri, Action<AsyncCompletedEventArgs> completedAction = null);
    void RemoveXap(string uri);
}

and implement it in the class “DeploymentCatalogService“:

[Export(typeof(IDeploymentCatalogService))]
public class DeploymentCatalogService : IDeploymentCatalogService
{
    private static AggregateCatalog _aggregateCatalog;

    Dictionary<string, DeploymentCatalog> _catalogs;

    public DeploymentCatalogService()
    {
        _catalogs = new Dictionary<string, DeploymentCatalog>();
    }

    public static void Initialize()
    {
        _aggregateCatalog = new AggregateCatalog();
        _aggregateCatalog.Catalogs.Add(new DeploymentCatalog());
        CompositionHost.Initialize(_aggregateCatalog);
    }

    public void AddXap(string uri, Action<AsyncCompletedEventArgs> completedAction = null )
    {
        DeploymentCatalog catalog;
        if (!_catalogs.TryGetValue(uri, out catalog))
        {
            catalog = new DeploymentCatalog(uri);
            if (completedAction != null)
                catalog.DownloadCompleted += (s, e) => completedAction(e);
            else
                catalog.DownloadCompleted += catalog_DownloadCompleted;

            catalog.DownloadAsync();
            _catalogs[uri] = catalog;
            _aggregateCatalog.Catalogs.Add(catalog);
        }
    }

    void catalog_DownloadCompleted(object sender, AsyncCompletedEventArgs e)
    {
        if (e.Error != null)
            throw e.Error;
    }

    public void RemoveXap(string uri)
    {
        DeploymentCatalog catalog;
        if (_catalogs.TryGetValue(uri, out catalog))
        {
            _aggregateCatalog.Catalogs.Remove(catalog);
        }
    }
}

The DeploymentCatalogService is initialized during the Application startup in this way:

private void Application_Startup(object sender, StartupEventArgs e)
{
    //Initialize the DeploymentCatalogService for MEF
    DeploymentCatalogService.Initialize();
    this.RootVisual = new MainPage();
}

When the user clicks on the Navigation bar, the container is loaded and filled with the content of the external XAP, all managed by MEF:

So we have a Navigation application which can dynamically load external “MEFModules” organized with a MVVM approach, contained in external XAPs and using an Event Aggregator to exchange messages, all managed by MEF.

This application can be easily extended inserting WCF RIA Services and/or Blend sample data for the design mode.

As usually the sample code is available for download here and will be soon available in the CodePlex project “MEF MVVM” – http://mefmvvm.codeplex.com.

Happy Silverlighting!

Multi-Touch enabling Silverlight Simon using Blend behaviors and the Surface sample for Silverlight

I have already blogged about using Blend behaviors to add Multi-Touch gestures and inertia effects to a generic Silverlight user control, so I wanted to use the same approach to add the same behaviors to the CodePlex project Simon.

I think that inserting multi-touch manipulation effects to a Silverlight application using Blend behaviors is an elegant way which makes the code very clear and readable.

To start you need to download the Multi-touch manipulation and inertia behavior (wow, more than 7000 downloads, great feedback! :)), which I already published on the Expression site.

This behavior is based on the code available in the Microsoft Surface Manipulations and Inertia Sample for Microsoft Silverlight, in my opinion the best example available for using multi-touch in Silverlight at this time.

The solution available contains a project named “MultiTouch.behaviors.Silverlight” which must be included in your application to enable the multi-touch functionalities.

To make the Silverlight/Blend Behavior work with Simon I’ve modified some code relative to the Zoom gesture in order to use a ScaleTransform (check out the source code on CodePlex: http://simon.codeplex.com).

To use the Behavior in XAML just add a reference to the “MultiTouch.Behaviors.Silverlight” project and use the following code:

<UserControl x:Class="SimonSilverlight.MainPage"
....
    xmlns:interactivity="clr-namespace:System.Windows.Interactivity; assembly=System.Windows.Interactivity"
    xmlns:multitouch="clr-namespace:MultiTouch.Behaviors.Silverlight; assembly=MultiTouch.Behaviors.Silverlight">
....
<Canvas>
    <uc:Simon x:Name="Says">
        <interactivity:Interaction.Behaviors>
            <multitouch:MultiTouchManipulationBehavior InertiaEnabled="True" TouchRotateEnabled="True"
                       TouchScaleEnabled="True" TouchTranslateEnabled="True"/>
        </interactivity:Interaction.Behaviors>
    </uc:Simon>
</Canvas>

Since we are using a Blend Behavior, we can also open the solution in Expression Blend, select the “MultiTouchManipulationBehavior” from the “Assets” section and drag it over the Simon control:

Happy Silverlighting!

Silverlight 4, MEF and MVVM: EventAggregator, ImportingConstructor and Unit Tests

I had recently the possibility to use MEF and Silverlight in a sample project together with Prism, this is for sure a great combination of frameworks for bulding applications using maintainable and extensible code. I don’t think that using MEF excludes the usage of Prism and vice versa,  the choice should be pondered and analyzed accordingly to the problem to solve.

Starting from the previous experiments, I decided to refactor and cleanup the MVVM approach in order to:

  • obtain simpler code;
  • inserting an EventAggregator managed by MEF to exchange messages;
  • maintaining the Visual Studio designer/Blend support;
  • trying a simple unit test using the framework available in the Silverlight Toolkit.
  1. Using the EventAggregator

The first step is inserting in the project the Prism EventAggregator downloading the “Microsoft.Practices.Composite.dll” and “Microsoft.Practices.Composite.Presentation.dll” libraries from the Prism site on Codeplex.

It’s now possible to make available in the application an instance of it using this syntax:

public class EventAggregatorProvider
{
   [Export(typeof(IEventAggregator))]
   public IEventAggregator eventAggregator { get { return new EventAggregator(); } }
}

In this way we are able to import it in the ViewModel class using an [ImportingConstructor] attribute:

[ImportingConstructor]
public MainPageViewModel(IEventAggregator eventAggregator, IDataItemsService dataItemsService)
{
   _eventAggregator = eventAggregator;
   _dataItemsService = dataItemsService;
}

When an [ImportingConstructor] is found, MEF looks for an [Export] for each parameter available in the constructor, in this case we must have exported an “IEventAggregator” and an “IDataItemsService”.

We are now able to access the instance of the EventAggregator and Publish/Subscribe to events using a syntax like:

//Call the Service
_dataItemsService.GetDataItems();

//Subscribe to the "DataItemsReceivedEvent"

_eventAggregator. GetEvent(). Subscribe(
    dataItemsReceived =>
    {
        this.dataItems = dataItemsReceived;
    },
    true
);

In this case we are receiving the result of the async calls via the EventAggregator and a DataItemsReceivedEvent:

public class DataItemsReceivedEvent : CompositePresentationEvent {  }

DataItemsService code publishing the Event:

//Initialize the collection
DataItemWcfService.DataItemServiceClient svc = new DataItemWcfService.DataItemServiceClient();
svc.GetDataItemsCompleted += (s1, e1) =>
{
    if (e1.Result != null)
    {
        var dataItems = new DataItems();
        e1.Result.ToList().ForEach(d =>
        {
            dataItems.Add(new DataItem() { Description = d.Description });
        });

        //Publish the DataItems
        _eventAggregator. GetEvent(). Publish(dataItems);

        isLoading = false;
    }
};
svc.GetDataItemsAsync();
isLoading = true;
}

2. Maintaining the Visual Studio designer/Blend support

In the previous experiments I enabled design-time data by inserting a new ViewModel class which can create some confusion, so I decided to skip this step and using a unique ViewModel following this approach:

  • the ViewModel parameterless constuctor contains the initialization for data to be used during design time and tests;
  • the other constructor marked with the MEF [ImportingConstructor] attribute enables initialization of services and event aggregator.
[ImportingConstructor]
public MainPageViewModel(IEventAggregator eventAggregator, IDataItemsService dataItemsService)
{
    _eventAggregator = eventAggregator;
    _dataItemsService = dataItemsService;
}

3 – Unit Test

To verify the approach described, I’ve inserted a new “Silverlight Unit Test project” to the solution (note that the “Silverlight Toolkit” must be installed to use this feature) and then a simple Test method containing the following code:

[TestClass]
public class Tests
{
    [TestMethod]
    [Description("Test the creation of a ViewModel and the initialization of Design/Test Data")]
    public void TestViewModelCreation()
    {
        var vm = new MainPageViewModel();
        Assert.IsNotNull(vm);
        Assert.AreEqual(vm.dataItems.Count, 2);
    }
}

Since MEF is only used to compose run-time Parts, I’m not using it in the Unit Tests.

So we have now a new piece of code, which I’ve called a “MEFModule” organized with a MVVM approach and ready for design-time support, unit tests and extensibility: ready to be inserted in a Navigation applicationdynamically loaded and enabled for design time using Blend Sample Data, stay tuned.

The source code is available for download here.

Happy Silverlighting!

A Silverlight / Expression Blend behavior to add Multi-Touch Manipulation and Inertia

I’ve updated the behavior available in the Expression Community gallery adding Multi-Touch manipulation (translation, rotation and zoom) and inertia effects using code from the Surface Manipulations and Inertia Sample for Microsoft Silverlight.

To enable Multi-Touch in your code simply download the behavior from here, add the project “MultiTouch.Behaviors.Silverlight” to a Visual Studio solution and then enable the gestures in XAML:

<UserControl x:Class="SilverlightMultiTouch.MainPage"
...
xmlns:interactivity="clr-namespace:System.Windows.Interactivity; assembly=System.Windows.Interactivity"
xmlns:behaviors="clr-namespace:MultiTouch.Behaviors.Silverlight; assembly=MultiTouch.Behaviors.Silverlight"
...
>

<Canvas>
  <Image Source="Images/Desert.jpg">
     <interactivity:Interaction.Behaviors>
         <behaviors:MultiTouchManipulationBehavior InertiaEnabled="True" TouchRotateEnabled="True" TouchTranslateEnabled="True" TouchScaleEnabled="True"/>
     </interactivity:Interaction.Behaviors>
  </Image>

  <Image Source="Images/Jellyfish.jpg">
     <interactivity:Interaction.Behaviors>
         <behaviors:MultiTouchManipulationBehavior InertiaEnabled="True" TouchRotateEnabled="True" TouchTranslateEnabled="True" TouchScaleEnabled="True"/>
     </interactivity:Interaction.Behaviors>
  </Image>
</Canvas>

The MultiTouchManipulationBehavior also contains some dependency properties (TouchRotateEnabled, TouchTranslateEnabled, TouchScaleEnabled and InertiaEnabled) to enable the corresponding gestures.

The example contains Multi-Touch manipulations applied to some Image controls and a Smooth streaming player of the Silverlight Media Framework.

I’ve also posted to CodePlex a sample using WPF 4 based on the article “Introduction to WPF 4 Multitouch” by Jaime Rodriguez.

Hope this helps and Happy Silverlighting!

Experiments using MEF, MVVM and Silverlight 4 Beta – Part 6: Design-mode ViewModel and calling a WCF Service

Note – this is a multi part post:

Today I had the opportunity to take a look at the code written in the previous posts and insert some new stuff in order to modify the project and make new experiments about:

  1. using a different ViewModel class for the design-time and run-time;
  2. using MEF combined with the new implicit styles feature available in Silverlight 4 Beta to initialize the DataContext of the View at run-time;
  3. retrieve the data using an async call to a WCF service and passing back the results to the VM via MEF.

1 – Using different VM classes

To accomplish this task I’ve defined a new interface named IMainPageViewModel defining these members:

/// MainPage ViewModel interface
public interface IMainPageViewModel : IViewModelBase
{
    string aViewModelProperty { get; set; }
    DataItems dataItems { get; set; }
    ICommand addDataItemCommand { get; }
}

This new interface is then implemented by two classes named ViewModels.DesignMode.MainPageViewModel and ViewModels.MainPageViewModel:

/// ViewModel for the "MainPageView" used in design-mode
public class MainPageViewModel : ViewModelBase, IMainPageViewModel
{
    public MainPageViewModel()
    {
        //Initialize the properties with test data if design mode
        aViewModelProperty = "Value - Design Mode";

        //Initialize the "dataItems" property
        dataItems = new DataItems();
        dataItems.Add(new DataItem() { Description = "Sample Data Item 1 - Design Mode" });
        dataItems.Add(new DataItem() { Description = "Sample Data Item 2 - Design Mode" });
    }

    public string aViewModelProperty { get; set; }

    public DataItems dataItems { get; set; }

    public ICommand addDataItemCommand { get; set; }
}
/// ViewModel class for the "MainPageView" using MEF
[PartCreationPolicy(CreationPolicy.NonShared)]
[Export(typeof(MainPageViewModel))]
public class MainPageViewModel : ViewModelBase, IMainPageViewModel
{
    public MainPageViewModel() {  }

    [Import("aViewModelPropertyTextProvider")]
    public string aViewModelProperty { get; set; }

    [Import(typeof(WcfDataItems))]
    public DataItems dataItems { get; set; }

    [Import(typeof(ICommand))]
    public PartCreator addDataItemCommandCreator { get; set; }

    private ICommand _addDataItemCommand;
    public ICommand addDataItemCommand
    {
        get {
            if (_addDataItemCommand==null)
                _addDataItemCommand = addDataItemCommandCreator.CreatePart().ExportedValue;
            return _addDataItemCommand;
        }
    }
}

The first one is associated with the View at design-time using an attached property which permits to bind an instance only at design time using this xaml (usually you should use <d:DesignProperties.DataContext>, here we are experimenting, of course):



    <!-- Design time DataContext -->
    
        
    

    ........

DesignTimeDataContext attached dependency property:

/// DesignDataContext Attached Dependency Property
public static readonly DependencyProperty DesignDataContextProperty =
    DependencyProperty.RegisterAttached("DesignDataContext", typeof(object), typeof(Page),
        new PropertyMetadata((object)null,
            new PropertyChangedCallback(OnDesignDataContextChanged)));

/// Gets the DesignDataContext property.
public static object GetDesignDataContext(DependencyObject d)
{
    return (object)d.GetValue(DesignDataContextProperty);
}

/// Sets the DesignDataContext property.
public static void SetDesignDataContext(DependencyObject d, object value)
{
    d.SetValue(DesignDataContextProperty, value);
}

/// Handles the DesignDataContext property changes
private static void OnDesignDataContextChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
    FrameworkElement element = (FrameworkElement)d;

    //Get the ViewModel instance only in design mode
    if ((Application.Current == null) || (Application.Current.GetType() == typeof(Application)))
       element.DataContext = e.NewValue;
}

And this is the design-time mode in Blend using the new attached property:

MEFMVVM Blend

2 – MEF and implicit styles

The new implict styles feature available in Silverlight 4 beta is used to initialize the DataContext of the MainPageView type in a declarative way in App.xaml:




    <!-- Run-time DataContext composed using MEF -->

In this case I’ve modified the MainPageViewModelMEFProvider class and inserted a new IViewModelProvider interface in order to obtain the instance of the ViewModel initialized by MEF:

/// Interface for the ViewModelProvider
public interface IViewModelProvider
{
    object GetViewModel { get; }
}
/// Get the ViewModel instance using MEF
public class MainPageViewModelMEFProvider : IViewModelProvider
{
    public MainPageViewModelMEFProvider() { }

    [Import(typeof(MainPageViewModel))]
    public IViewModelBase ViewModel { get; set; }

    /// Get the Instance of the ViewModel using MEF
    public object GetViewModel
    {
        get
        {
           PartInitializer.SatisfyImports(this);
           return ViewModel;
        }
    }
}

3 – retrieve the data using an async call to a WCF service

I’ve added to the solution a simple WCF service which returns a collection of DataItems:

[ServiceContract(Namespace = "")]
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
public class DataItemService : IDataItemService
{
    [OperationContract]
    public List GetDataItems()
    {
        // Add your operation implementation here
        return new List()
        {
            new DataItemFromService() {Description="DataItem from service 1"},
            new DataItemFromService() {Description="DataItem from service 2"},
            new DataItemFromService() {Description="DataItem from service 3"}
        };
    }
}

interface IDataItemService
{
    List GetDataItems();
}

public class DataItemFromService
{
    public string Description { get; set; }
}

Since the project uses MEF composition and [Import] /[Export] attributes to initialize all the members of the VM class, I’ve used the same approach for the dataItems collection, retrieving data from an async call to the WCF service using a WcfDataItems class:

/// A sample collection of DataItems from WCF
[Export(typeof(WcfDataItems))]
public class WcfDataItems : DataItems
{
    public WcfDataItems()
    {
        //Initialize the collection
        DataItemWcfService.DataItemServiceClient svc = new DataItemWcfService.DataItemServiceClient();
        svc.GetDataItemsCompleted += (s1, e1) =>
        {
            if (e1.Result != null)
                e1.Result.ToList().ForEach(d =>
                    {
                        //Retrieve a new DataItem
                        DataItem di = DataItemCreator.CreatePart().ExportedValue;
                        di.Description = d.Description;
                        this.Add(di);
                    });
            isLoading = false;
        };
        svc.GetDataItemsAsync();
        isLoading = true;
    }

    [Import(typeof(DataItem))]
    public PartCreator DataItemCreator { get; set; }
}

The code is available for download here.

Happy Silverlighting!

Experiments using MEF, MVVM and Silverlight 4 Beta – Part 5: Enabling Blend and the Visual Studio designer

Note – this is a multi part post:

In the last post I’ve updated the sample project introducing PartCreator<T>, in this one I will illustrate a method to make available sample data during the editing of the solution in Blend or in the Visual Studio designer, in order to obtain a result like this (a similar approach is used in the awesome MVVM light toolkit by Laurent Bugnion):

MEFMVVM Blend

First of all, I’ve created a class ViewModelProvider to obtain dinamically an instance of the ViewModel and directly used in xaml to create the VM instance, in this way it’s possibile to see sample data during the design phase:

public class ViewModelProvider : IViewModelProvider
{
    public ViewModelProvider() { }

    [Import(typeof(MainPageViewModel))]
    public IViewModelBase mainPageViewModelProvider { get; set; }

    ///

    /// Get the Instance of the ViewModel
    /// 

    public IViewModelBase GetVMInstance
    {
        get
        {
            //Verify if Design Mode
            if ((Application.Current == null) || (Application.Current.GetType() == typeof(Application)))
            {
                return new MainPageViewModel();
            }
            else
            {
                //If not in Design Mode uses MEF to compose the objects
                PartInitializer.SatisfyImports(this);
                return mainPageViewModelProvider;
            }
        }
    }
}

I’ve not already found a method to activate MEF compositions during design time, so an instance of the ViewModel class is explicitely created in code if we are in the tool designers, otherwise SatisfyImports() executes the MEF magic as usually.

It’s now necessary to initialize the properties values in order to display sample data at design time, this step can be done in the constructor of the MainPageViewModel:

[PartCreationPolicy(CreationPolicy.NonShared)]
[Export(typeof(MainPageViewModel))]
public class MainPageViewModel : ViewModelBase, IMainPageViewModel
{
    ///
    /// Default constructor
    ///
    public MainPageViewModel()
    {
        if ((Application.Current == null) || (Application.Current.GetType()==typeof(Application)))
        {
            //Initialize the properties with test data if design mode
            aViewModelProperty = "Value - Design Mode";
            dataItems = new SampleDataItems(); dataItems.ToList().ForEach(d=>d.Description+=" - Design Mode");
        }
    }

    ///
    /// A sample property
    ///
    [Import("aViewModelPropertyTextProvider")]
    public string aViewModelProperty { get; set; }

    ///
    /// A sample collection
    ///
    [Import(typeof(DataItems))]
    public DataItems dataItems { get; set; }

    ///
    /// A Part creator for the addDataItemCommandCreator
    ///
    [Import(typeof(ICommand))]
    public PartCreator addDataItemCommandCreator { get; set; }

    private ICommand _addDataItemCommand;
    public ICommand addDataItemCommand
    {
        get {
            if (_addDataItemCommand==null)
                _addDataItemCommand = addDataItemCommandCreator.CreatePart().ExportedValue;
            return _addDataItemCommand;
        }
    }
}

Inside Visual Studio, it’s now possibile to edit the User Interface and visualize the sample data defined in the constructor:

VisualStudio2010

The source code is available for download here.

Hope this helps!