Porting from WPF to Silverlight: The Missing Pieces, Part 1

Recently I’ve been working on a port of a WPF 3.5 application into a Silverlight 3 web application. I came across many of the limitations of Silverlight 3 relative to WPF 3.5.

Fortunately, I’ve found numerous excellent solutions throughout the blogosphere. These have helped me so much I would like to note them for all to see. Also, this list might come in handy to other people porting applications from WPF to Silverlight.

One final note, the port was done from WPF 3.5 to Silverlight 3. Some of the issues might have been solved in Silverlight 4 or have different solutions.

No Commands

Description: Silverlight 3 lacks proper support for commands.

Although Silverlight 3 does have the definition of ICommand, the buttons don’t have a Command property to bind with.

Solution by: Patrick Cauldwell

http://www.cauldwell.net/patrick/blog/MVVMBindingToCommandsInSilverlight.aspx

In a nutshell:

Instead of writing:

<Button 
    Content="Say Hello" 
    Command="{Binding Path=SayHello}"
    />

Use the code in the post and write:

<Button 
    Content="Say Hello" 
    my:ButtonService.Command="{Binding Path=SayHello}"
    />

No ClipToBounds

Description: Silverlight 3 lacks support for ClipToBounds.

Solution by: Colin Eberhardt

http://www.scottlogic.co.uk/blog/colin/2009/05/silverlight-cliptobounds-can-i-clip-it-yes-you-can/

In a nutshell:

Instead of writing:

<Grid 
    Background="Yellow" 
    Margin="20,40,-20,20" 
    ClipToBounds="True"
    >
    ...
</Grid>

Use the code in the post and write:

<Grid 
    Background="Yellow" 
    Margin="20,40,-20,20" 
    util:Clip.ToBounds="True"
    >
    ...
</Grid>

No DataContextChanged Event

Description: Silverlight 3 doesn’t have the DataContextChanged event.

Solution by: Emiel Jongerius

http://www.pochet.net/blog/2010/06/16/silverlight-datacontext-changed-event-and-trigger/

In a nutshell:

Instead of writing:

MyControl.DataContextChanged += MyControl_DataContextChanged;

Use the code in the post and write:

DataContextChangedHelper.AddDataContextChangedHandler(MyControl, 
    MyControl_DataContextChanged);

No DataTrigger

Description: Silverlight 3 doesn’t have data triggers, it uses a completely different model, using VisualStateManager.

Solution by: Pete Blois

http://blois.us/blog/2009/04/datatrigger-bindings-on-non.html

In a nutshell:

Instead of writing:

<DataTrigger Binding="{Binding IsLoaded}" Value="True">    ... DOING STUFF<DataTrigger>

Use the code in the post and write:

<i:Interaction.Behaviors>
    <id:DataStateSwitchBehavior Binding='{Binding IsLoaded}'>
        <id:DataStateSwitchCase Value='True' State='Loaded'/>
    </id:DataStateSwitchBehavior>
</i:Interaction.Behaviors>

Of course, you should define a state that does the same “STUFF”.

The transition is not immediate, but at least it provides the same functionality as data triggers.

To Be Continued...

That’s it for now,
Arik Poznanski.