Question

We have a (massive) legacy WinForms app which, through a menu item, opens up a WPF form. This WPF form will host an Infragistics grid, and some buttons/drop-downs.

This lone WPF form represents the nascent stage of a migration to WPF. Later on, more components of the app will move to WPF, and ultimately the entire app itself.

As part of the migration, we would like to use Caliburn Micro. Hence, it would be nice if we could start by using it with this lone WPF form.

• Can someone please provide some pointers on how to use Caliburn Micro with the WPF form?
• Or perhaps tell me why it may not make sense to use Caliburn Micro just yet?

The documentation I’ve read so far involves boot strappers that ensure the application starts with the desired root view model, rather than the scenario above.

Many thanks!

Answer 1

After much Googling and going through the Caliburn Micro source code, I’ve come up with an approach that works in a sample test application. I can’t post the test application here for certain reasons, but here’s the approach in a nutshell.

• Create a WinForm with a button.
• On button click, show a ChildWinForm

• In the load handler of the ChildWinForm:

  
  // You'll need to reference WindowsFormsIntegration for the ElementHost class
  // ElementHost acts as the "intermediary" between WinForms and WPF once its Child
  // property is set to the WPF control. This is done in the Bootstrapper below.    
  var elementHost = new ElementHost{Dock = DockStyle.Fill};
  Controls.Add(elementHost);
  new WpfControlViewBootstrapper(elementHost);
  

• The bootstrapper above is something you’ll have to write.

• For more information about all it needs to do, see Customizing the Bootstrapper from the Caliburn Micro documentation.
• For the purposes of this post, make it derive from the Caliburn Bootstrapper class.

• It should do the following in its constructor:

  
  // Since this is a WinForms app with some WPF controls, there is no Application.
  // Supplying false in the base prevents Caliburn Micro from looking
  // for the Application and hooking up to Application.Startup
  protected WinFormsBootstrapper(ElementHost elementHost) : base(false)
  {
      // container is your preferred DI container
      var rootViewModel = container.Resolve();
      // ViewLocator is a Caliburn class for mapping views to view models
      var rootView = ViewLocator.LocateForModel(rootViewModel, null, null);
      // Set elementHost child as mentioned earlier
      elementHost.Child = rootView;
  }
  

• Last thing to note is that you’ll have to set the cal:Bind.Model dependency property in the XAML of WpfControlView.

  
  cal:Bind.Model="WpfControls.ViewModels.WpfControl1ViewModel"
  

• The value of the dependency property is used passed as a string to Bootstrapper.GetInstance(Type serviceType, string key), which must then use it to resolve the WpfControlViewModel.

• Since the container I use (Autofac), doesn’t support string-only resolution, I chose to set the property to the fully qualified name of the view model. This name can then be converted to the type, and used to resolve from the container.