Alexey Zakharov's Blog : Silverlight

TileMode feature request for Silverlight 4

brainbox — Tue, 29 Dec 2009 16:54:00 GMT

After using of SL 4 beta I found that there is still no tilemode support in imagebrush.

This feature is extreamely useful when u want to fill some area with image pattern like wood, steel or some other material. HTML CSS supports this from the ancient time with repeat-x property and that was really bad surprise for us when we find it missing in Silverlight.

One guy have already reported this feature in Silverlight Feature Request Web site

I hope that you, my readers will join me and vote for this feature.

New article for SilverlightShow: Deep Dive Into Silverlight Services Part 2: Serialization on the speed of light with Google Protocol Buffers

brainbox — Tue, 22 Dec 2009 18:26:00 GMT

I've written new article for SilverlightShow.net. In this article I’ve showed how you can use ASP.NET MVC and Google Protocol Buffers to create fast and scalable REST services. Enjoy!

Silverlight came to Opera 10

brainbox — Fri, 23 Oct 2009 17:20:00 GMT

Today I discovered that Opera 10 supports Silverlight. So now it is possible to say that on windows platform Silverlight is really crossbrowser.

Official Opera post.

Issues of Silverlight style system

brainbox — Wed, 14 Oct 2009 03:15:00 GMT

Perhaps the second annoying problem after incomplete binding support is poor style system of Silverlight.

Here is the main two issues.

1. Styles are not compatible with on demand application loading. Imagine you want to share style dictionary among a set of application modules (something like PRISM module). The source of problem is xaml reader, which parse resource dictionary with shared style. To successfully parse dictionary it requires all controls dll to be loaded. But these controls dll are loaded on demand if module needs them.That is why if you for example load module A which doesn't requires any control libraries, but uses shared style dictionary u will get XamlParseException. We are currently hacking this issue by manual resource dictionary parsing. But it is just another dirty HACK!

2. Silverlight doesn't support dynamic resource so it is not impossible to create application themes (What you see in toolkit is just a Hack that is not support changing of theme and works rather slowly). You simply cannot change style of element if it was set once.

If you have and ideas how to solve it or you are Microsoft guy ;-) which can fix it please email me or leave a comment.

Silverlight feature request site

brainbox — Fri, 04 Sep 2009 17:06:07 GMT

Today I’ve found a very nice Silverlight feature request site and I’d like to introduce MY MOST WANTED REQUEST.

Full (WPF) databinding support:

1. Binding of non-framework elements. (Now you cannot bind properties of Behaviors and Triggers)

2. Binding of style setter

3. Ancestor relative source binding

4. x:Type x:Static ...

PS: We really tired of Silverlight data binding hacks =( Please save our nerves.

Silverlight DataForm Auto Generation Horror!

brainbox — Sat, 01 Aug 2009 08:16:18 GMT

Today I was trying to use automatic generation of DataForm from my ViewModels.

After an hour of exploring it I recognized that it is nightmare!

Look at this method:

        1: private static Control GetControlFromType(Type type)

       2: {

       3:     Debug.Assert(type != null, "The type must not be null.");

       4:  

       5:     if (type == typeof(bool))

       6:     {

       7:         return new CheckBox();

       8:     }

       9:     else if (type == typeof(bool?))

    {

        CheckBox checkBox = new CheckBox();

        checkBox.IsThreeState = true;

        return checkBox;

    }

    else if (type == typeof(DateTime) || type == typeof(DateTime?))

    {

        return new DatePicker();

    }

    else if (type.IsEnum)

    {

        ComboBox comboBox = new ComboBox();

  

        FieldInfo[] valueFieldInfos = type.GetFields(BindingFlags.Public | BindingFlags.Static);

        List<string> valueList = new List<string>();

  

        foreach (FieldInfo valueFieldInfo in valueFieldInfos)

        {

            Enum value = valueFieldInfo.GetValue(null) as Enum;

  

            if (value != null)

            {

                valueList.Add(value.ToString());

            }

        }

  

        comboBox.ItemsSource = valueList;

        return comboBox;

    }

    else

    {

        return new TextBox();

    }

}

You see that HARDCODED controls? It is terrible mistake.

What if I want to use Telerik controls?

What if I want to have NumericUpDown for int field?

Also I often need different editors for the same value type.

IMHO the right solution is to set up generated control with some custom annotation of model properties.

Perhaps the main reason to use DataForm is its auto generation. But it is now totally unusable even for simple models.

Already released DataGrid has the same issue too.

Also I think that edit, add, submit button should not present in DataForm control at all.

PS: The only way is to generate datafield properly is overriding of OnAutoGeneratingField, but it is HACK!

New article for SilverlightShow: Deep Dive Into WCF Part 1: TDD

brainbox — Sat, 25 Jul 2009 07:09:29 GMT

I've written new article for SilverlightShow.net. In this article I’ve showed some approaches, which make WCF more TDD friendly. Enjoy!

Deep zooming on the fly

brainbox — Mon, 15 Jun 2009 17:27:09 GMT

I’ve just published new article about dynamic deep zooming. With this approach you can make existent high quality site image zoomable without any preparations.

Hope you will enjoy it!

Silverlight Tips & Tricks: Make Silverlight DataGrid be more MVVM friendly =)

brainbox — Sat, 06 Jun 2009 17:21:55 GMT

Today one guy from our dev team met some problems with binding of datagrid selected items. Because of SelectedItems is readonly property, we cannot create two way binding for it. After a short discussion we decided to create DataGridSelectedChanged command behavior which will inform our model about selected rows. (We are using microsoft p&p prism commands api).

To create new command behavior you should perform to steps:

1. Create behaviour

        1: public class DataGridSelectionChangedCommandBehaviour : CommandBehaviourBase<DataGrid>

       2: {

       3:     public DataGridSelectionChangedCommandBehaviour(DataGrid targetObject)

       4:         : base(targetObject)

       5:     {

       6:         targetObject.SelectionChanged += this.OnSelectionChanged;

       7:     }

       8:  

       9:     private void OnSelectionChanged(object sender, SelectionChangedEventArgs e)

      10:     {

      11:         this.ExecuteCommand();

      12:     }

      13: }

2. Add attached property

       1: public static class SelectionChanged

       2: {

       3:     /// <summary>

       4:     /// Command paramter.

       5:     /// </summary>

       6:     public static readonly DependencyProperty CommandParameterProperty =

       7:         DependencyProperty.RegisterAttached(

       8:             "CommandParameter", typeof(object), typeof(SelectionChanged), new PropertyMetadata(OnSetCommandParameterCallback));

       9:  

    /// <summary>

    /// Command to execute on click event.

    /// </summary>

    public static readonly DependencyProperty CommandProperty = DependencyProperty.RegisterAttached(

        "Command", typeof(ICommand), typeof(SelectionChanged), new PropertyMetadata(OnSetCommandCallback));

  

    /// <summary>

    ///  Command behavior.

    /// </summary>

    private static readonly DependencyProperty ClickCommandBehaviorProperty =

        DependencyProperty.RegisterAttached(

            "ClickCommandBehavior", typeof(DataGridSelectionChangedCommandBehaviour), typeof(SelectionChanged), null);

  

    /// <summary>

    /// Gets command

    /// </summary>

    /// <param name="dataGrid">

    /// containig dependecy property

    /// </param>

    /// <returns>

    /// attached command

    /// </returns>

    public static ICommand GetCommand(DataGrid dataGrid)

    {

        return dataGrid.GetValue(CommandProperty) as ICommand;

    }

  

    /// <summary>

    /// Gets command parameter

    /// </summary>

    /// <param name="dataGrid">

    /// containig dependecy property

    /// </param>

    /// <returns>

    /// attached command

    /// </returns>

    public static object GetCommandParameter(DataGrid dataGrid)

    {

        return dataGrid.GetValue(CommandParameterProperty) as object;

    }

  

    /// <summary>

    /// Sets the <see cref="ICommand"></see> for execute

    /// </summary>

    /// <param name="dataGrid">

    /// dependency object to attache command

    /// </param>

    /// <param name="command">

    /// command for execute

    /// </param>

    public static void SetCommand(DataGrid dataGrid, ICommand command)

    {

        dataGrid.SetValue(CommandProperty, command);

    }

  

    /// <summary>

    /// Sets the value for the CommandParameter attached property on the provided <see cref="DataGrid"/>.

    /// </summary>

    /// <param name="dataGrid">

    /// dependency object to attach CommandParameter

    /// </param>

    /// <param name="parameter">

    /// Parameter value to attach

    /// </param>

    public static void SetCommandParameter(DataGrid dataGrid, object parameter)

    {

        dataGrid.SetValue(CommandParameterProperty, parameter);

    }

  

    /// <summary>

    /// Get or create command behavior

    /// </summary>

    /// <param name="dataGrid">

    /// dependecy object to attach

    /// </param>

    /// <returns>

    /// click behavior

    /// </returns>

    private static DataGridSelectionChangedCommandBehaviour GetOrCreateBehavior(DataGrid dataGrid)

    {

        var behavior = dataGrid.GetValue(ClickCommandBehaviorProperty) as DataGridSelectionChangedCommandBehaviour;

        if (behavior == null)

        {

            behavior = new DataGridSelectionChangedCommandBehaviour(dataGrid);

            dataGrid.SetValue(ClickCommandBehaviorProperty, behavior);

        }

  

        return behavior;

    }

  

    /// <summary>

    /// On set command

    /// </summary>

    /// <param name="dependencyObject">

    /// dependecy object to attach command

    /// </param>

    /// <param name="e">

    /// event args

    /// </param>

    private static void OnSetCommandCallback(

        DependencyObject dependencyObject, DependencyPropertyChangedEventArgs e)

    {

        var dataGrid = dependencyObject as DataGrid;

        if (dataGrid != null)

        {

            DataGridSelectionChangedCommandBehaviour behaviour = GetOrCreateBehavior(dataGrid);

            behaviour.Command = e.NewValue as ICommand;

        }

    }

  

    /// <summary>

    /// On set command parameter.

    /// </summary>

    /// <param name="dependencyObject">

    /// dependency object to attach command

    /// </param>

    /// <param name="e">

    /// event args

    /// </param>

    private static void OnSetCommandParameterCallback(

        DependencyObject dependencyObject, DependencyPropertyChangedEventArgs e)

    {

        var dataGrid = dependencyObject as DataGrid;

        if (dataGrid != null)

        {

            DataGridSelectionChangedCommandBehaviour behavior = GetOrCreateBehavior(dataGrid);

            behavior.CommandParameter = e.NewValue;

        }

    }

}

Now we can invoke DelegateCommand on SelectedChanged event and pass SelectedItems DataGrid property using relative binding.

       1: <data:DataGrid 

       2:     ItemsSource="{Binding Items}" 

       3:     Behaviours:SelectionChanged.Command="{Binding SelectedFilesChangedCommand}" 

       4:     Behaviours:SelectionChanged.CommandParameter="{Binding RelativeSource={RelativeSource Self}, Path=SelectedItems}" 

       5:     >               

       6: </data:DataGrid>

Hope it will help you in your coding wars with silverlight controls =)))

New article for SilverlightShow

brainbox — Thu, 28 May 2009 17:57:17 GMT

Hi Silverlighters,

I've just published my new article about Silverlight sockets.

Hope you will enjoy reading!

Silverlight Tip: Problems with polling duplex inactivitytimeout.

brainbox — Fri, 17 Apr 2009 08:53:00 GMT

Many people ask question why polling duplex session shutdown after 10 minutes in spite of polling duplex InactivityTimeout value is more than hour.

In private email Christopher Scrosati (Silverlight WS Team) told me that I've also should configure ReciveTimout.

Here is the code sample, which shows how to configure polling duplex correctly:

HttpTransportBindingElement http = new HttpTransportBindingElement();

BinaryMessageEncodingBindingElement binary = new BinaryMessageEncodingBindingElement();

PollingDuplexBindingElement polling = new PollingDuplexBindingElement();

polling.InactivityTimeout = TimeSpan.FromHours(1);

CustomBinding binding = new CustomBinding(polling, binary, http);

binding.ReceiveTimeout = TimeSpan.FromHours(1);

Hope it helps! Many thanks to Christopher =)

How to increase amount of silverlight duplex clients.

brainbox — Thu, 16 Apr 2009 19:43:00 GMT

Amount of silverlight polling duplex clients is defined by MaxConcurrentSessions throttling property. Default value is 10.

To increase it you should programmatically add ServiceThrottlingBehavior.

Here is some code that shows how it could be done:

    
public class YourDuplexServiceFactory : ServiceHostFactoryBase
    
{
    
    public override ServiceHostBase CreateServiceHost(string constructorString,
    
                                                      Uri[] baseAddresses)
    
    {
    
        return new PollingDuplexSimplexServiceHost(baseAddresses);
    
    }
    
}
    
  
    
internal class PollingDuplexSimplexServiceHost : ServiceHost
    
{
    
    public PollingDuplexSimplexServiceHost(params Uri[] addresses)
    
    {
    
        InitializeDescription(typeof(YourDuplexService), new UriSchemeKeyedCollection(addresses));
    
        Description.Behaviors.Add(new ServiceMetadataBehavior());
    
  
    
        var throttle = Description.Behaviors.Find<ServiceThrottlingBehavior>();
    
        if (throttle == null)
    
        {
    
            throttle = new ServiceThrottlingBehavior
    
                           {
    
                               MaxConcurrentCalls = 12,
    
                               MaxConcurrentSessions = 34,
    
                               MaxConcurrentInstances = 56
    
                           };
    
            Description.Behaviors.Add(throttle);
    
        }
    
    }
    
  
    
    protected override void InitializeRuntime()
    
    {
    
        // Add an endpoint for the given service contract.
    
        AddServiceEndpoint(
    
            typeof(IYourDuplexService),
    
            new CustomBinding(
    
                new PollingDuplexBindingElement
    
                    {
    
                        InactivityTimeout = TimeSpan.FromSeconds(3600)
    
                    },
    
                new BinaryMessageEncodingBindingElement(),
    
                new HttpTransportBindingElement()),
    
            "");
    
  
    
        // Add a metadata endpoint.
    
        AddServiceEndpoint(
    
            typeof (IMetadataExchange),
    
            MetadataExchangeBindings.CreateMexHttpBinding(),
    
            "mex");
    
  
    
        base.InitializeRuntime();
    
    }
    
}

PS: I don't like how duplex services work. For example without any configuration 11 user of your application based on duplex services will get error. Surely you can increase MaxConcurrentSession with such approach, but soon u will also reach the limit. If you have got same experience please write about it in comments!!!!

Silverlight Tip: If Polling Duplex SLOWS Everything =)

brainbox — Fri, 10 Apr 2009 18:00:00 GMT

Today I've lost about 6 hours to find out why POLLING DUPLEX make all my WCF services work extremely SLOW. The reason was Global.ashx. Don't know why it caused such problems, but when I've deleted it everything started working correctly.

Microsoft business start 2009 Winner!

brainbox — Mon, 23 Mar 2009 18:49:00 GMT

I'd like to say thanks for all people who helped us to prepare for Microsoft business start 2009!

Now we can surely say that our secret Silverlight project will be created! =)

B&Z LLC Forever! =)

SilverlightShow Author

brainbox — Thu, 05 Mar 2009 07:05:00 GMT

Today I officially join SIlverlightShow.net author's team.

Here is a list with all articles that I've already written for SilverlightShow:

1. Virtual earth deep zooming – 1st place Write and Win II
2. ADO.NET Data Services Advanced Topics - Custom proxy based on T4 templates

My future articles are going to be about the following topics: ADO.NET Data Services, Prism, DLR and Silverlight Application Design patterns.