Restored code lost in migration (#12652)

* Restored code lost in migration

* Fixed broken code reference

* added dev_langs

Author: Ron Petrusha

docs/framework/wpf/app-development/how-to-create-an-add-in-that-is-a-ui.md

@@ -1,6 +1,9 @@
 ---
 title: "How to: Create an Add-In That Is a UI"
 ms.date: "03/30/2017"
+dev_langs: 
+  - "csharp"
+  - "vb"
 helpviewer_keywords: 
   - "creating an add-in that is a UI [WPF]"
   - "add-ins [WPF], UI"
@@ -27,57 +30,79 @@ This example shows how to create an add-in that is a Windows Presentation Founda
  To create an add-in that is a WPF UI requires specific code for each pipeline segment, the add-in, and the host application.  
 
 <a name="Contract"></a>   
-## Implementing the Contract Pipeline Segment  
- When an add-in is a UI, the contract for the add-in must implement <xref:System.AddIn.Contract.INativeHandleContract>. In the example, `IWPFAddInContract` implements <xref:System.AddIn.Contract.INativeHandleContract>, as shown in the following code.  
-  
- [!code-csharp[SimpleAddInIsAUISample#ContractCode](~/samples/snippets/csharp/VS_Snippets_Wpf/SimpleAddInIsAUISample/CSharp/Contracts/IWPFAddInContract.cs#contractcode)]  
+## Implementing the Contract Pipeline Segment
+
+When an add-in is a UI, the contract for the add-in must implement <xref:System.AddIn.Contract.INativeHandleContract>. In the example, `IWPFAddInContract` implements <xref:System.AddIn.Contract.INativeHandleContract>, as shown in the following code.  
 
+[!code-csharp[SimpleAddInIsAUISample#ContractCode](~/samples/snippets/csharp/VS_Snippets_Wpf/SimpleAddInIsAUISample/CSharp/Contracts/IWPFAddInContract.cs#contractcode)]
+[!code-vb[SimpleAddInIsAUISample#ContractCode](~/samples/snippets/visualbasic/VS_Snippets_Wpf/SimpleAddInIsAUISample/VisualBasic/Contracts/IWPFAddInContract.vb#contractcode)]
+
 <a name="AddInViewPipeline"></a>   
-## Implementing the Add-In View Pipeline Segment  
- Because the add-in is implemented as a subclass of the <xref:System.Windows.FrameworkElement> type, the add-in view must also subclass <xref:System.Windows.FrameworkElement>. The following code shows the add-in view of the contract, implemented as the `WPFAddInView` class.  
-  
- [!code-csharp[SimpleAddInIsAUISample#AddInViewCode](~/samples/snippets/csharp/VS_Snippets_Wpf/SimpleAddInIsAUISample/CSharp/AddInViews/WPFAddInView.cs#addinviewcode)]  
+## Implementing the Add-In View Pipeline Segment
+
+Because the add-in is implemented as a subclass of the <xref:System.Windows.FrameworkElement> type, the add-in view must also subclass <xref:System.Windows.FrameworkElement>. The following code shows the add-in view of the contract, implemented as the `WPFAddInView` class.  
 
- Here, the add-in view is derived from <xref:System.Windows.Controls.UserControl>. Consequently, the add-in UI should also derive from <xref:System.Windows.Controls.UserControl>.  
+[!code-csharp[SimpleAddInIsAUISample#AddInViewCode](~/samples/snippets/csharp/VS_Snippets_Wpf/SimpleAddInIsAUISample/CSharp/AddInViews/WPFAddInView.cs#addinviewcode)]  
+[!code-vb[SimpleAddInIsAUISample#AddInViewCode](~/samples/snippets/visualbasic/VS_Snippets_Wpf/SimpleAddInIsAUISample/VisualBasic/AddInViews/WPFAddInView.vb#AddInViewCode)]  
 
-<a name="AddInSideAdapter"></a>   
-## Implementing the Add-In-Side Adapter Pipeline Segment  
- While the contract is an <xref:System.AddIn.Contract.INativeHandleContract>, the add-in is a <xref:System.Windows.FrameworkElement> (as specified by the add-in view pipeline segment). Therefore, the <xref:System.Windows.FrameworkElement> must be converted to an <xref:System.AddIn.Contract.INativeHandleContract> before crossing the isolation boundary. This work is performed by the add-in-side adapter by calling <xref:System.AddIn.Pipeline.FrameworkElementAdapters.ViewToContractAdapter%2A>, as shown in the following code.  
+Here, the add-in view is derived from <xref:System.Windows.Controls.UserControl>. Consequently, the add-in UI should also derive from <xref:System.Windows.Controls.UserControl>.  
 
- [!code-csharp[SimpleAddInIsAUISample#AddInSideAdapterCode](~/samples/snippets/csharp/VS_Snippets_Wpf/SimpleAddInIsAUISample/CSharp/AddInSideAdapters/WPFAddIn_ViewToContractAddInSideAdapter.cs#addinsideadaptercode)]  
+<a name="AddInSideAdapter"></a>
+## Implementing the Add-In-Side Adapter Pipeline Segment
+
+While the contract is an <xref:System.AddIn.Contract.INativeHandleContract>, the add-in is a <xref:System.Windows.FrameworkElement> (as specified by the add-in view pipeline segment). Therefore, the <xref:System.Windows.FrameworkElement> must be converted to an <xref:System.AddIn.Contract.INativeHandleContract> before crossing the isolation boundary. This work is performed by the add-in-side adapter by calling <xref:System.AddIn.Pipeline.FrameworkElementAdapters.ViewToContractAdapter%2A>, as shown in the following code.  
 
- In the add-in model where an add-in returns a UI (see [Create an Add-In That Returns a UI](how-to-create-an-add-in-that-returns-a-ui.md)), the add-in adapter converted the <xref:System.Windows.FrameworkElement> to an <xref:System.AddIn.Contract.INativeHandleContract> by calling <xref:System.AddIn.Pipeline.FrameworkElementAdapters.ViewToContractAdapter%2A>. <xref:System.AddIn.Pipeline.FrameworkElementAdapters.ViewToContractAdapter%2A> must also be called in this model, although you need to implement a method from which to write the code to call it. You do this by overriding <xref:System.AddIn.Pipeline.ContractBase.QueryContract%2A> and implementing the code that calls <xref:System.AddIn.Pipeline.FrameworkElementAdapters.ViewToContractAdapter%2A> if the code that is calling <xref:System.AddIn.Pipeline.ContractBase.QueryContract%2A> is expecting an <xref:System.AddIn.Contract.INativeHandleContract>. In this case, the caller will be the host-side adapter, which is covered in a subsequent subsection.  
+[!code-csharp[SimpleAddInIsAUISample#AddInSideAdapterCode](~/samples/snippets/csharp/VS_Snippets_Wpf/SimpleAddInIsAUISample/CSharp/AddInSideAdapters/WPFAddIn_ViewToContractAddInSideAdapter.cs#addinsideadaptercode)]  
+[!code-vb[SimpleAddInIsAUISample#AddInSideAdapterCode](~/samples/snippets/visualbasic/VS_Snippets_Wpf/SimpleAddInIsAUISample/VisualBasic/AddInSideAdapters/WPFAddIn_ViewToContractAddInSideAdapter.vb#addinsideadaptercode)]
+
+In the add-in model where an add-in returns a UI (see [Create an Add-In That Returns a UI](how-to-create-an-add-in-that-returns-a-ui.md)), the add-in adapter converted the <xref:System.Windows.FrameworkElement> to an <xref:System.AddIn.Contract.INativeHandleContract> by calling <xref:System.AddIn.Pipeline.FrameworkElementAdapters.ViewToContractAdapter%2A>. <xref:System.AddIn.Pipeline.FrameworkElementAdapters.ViewToContractAdapter%2A> must also be called in this model, although you need to implement a method from which to write the code to call it. You do this by overriding <xref:System.AddIn.Pipeline.ContractBase.QueryContract%2A> and implementing the code that calls <xref:System.AddIn.Pipeline.FrameworkElementAdapters.ViewToContractAdapter%2A> if the code that is calling <xref:System.AddIn.Pipeline.ContractBase.QueryContract%2A> is expecting an <xref:System.AddIn.Contract.INativeHandleContract>. In this case, the caller will be the host-side adapter, which is covered in a subsequent subsection.  
 
 > [!NOTE]
 >  You also need to override <xref:System.AddIn.Pipeline.ContractBase.QueryContract%2A> in this model to enable tabbing between host application UI and add-in UI. For more information, see "WPF Add-In Limitations" in [WPF Add-Ins Overview](wpf-add-ins-overview.md).  
   
- Because the add-in-side adapter implements an interface that derives from <xref:System.AddIn.Contract.INativeHandleContract>, you also need to implement <xref:System.AddIn.Contract.INativeHandleContract.GetHandle%2A>, although this is ignored when <xref:System.AddIn.Pipeline.ContractBase.QueryContract%2A> is overridden.  
+Because the add-in-side adapter implements an interface that derives from <xref:System.AddIn.Contract.INativeHandleContract>, you also need to implement <xref:System.AddIn.Contract.INativeHandleContract.GetHandle%2A>, although this is ignored when <xref:System.AddIn.Pipeline.ContractBase.QueryContract%2A> is overridden.  
 
 <a name="HostViewPipeline"></a>   
-## Implementing the Host View Pipeline Segment  
- In this model, the host application typically expects the host view to be a <xref:System.Windows.FrameworkElement> subclass. The host-side adapter must convert the <xref:System.AddIn.Contract.INativeHandleContract> to a <xref:System.Windows.FrameworkElement> after the <xref:System.AddIn.Contract.INativeHandleContract> crosses the isolation boundary. Because a method isn't being called by the host application to get the <xref:System.Windows.FrameworkElement>, the host view must "return" the <xref:System.Windows.FrameworkElement> by containing it. Consequently, the host view must derive from a subclass of <xref:System.Windows.FrameworkElement> that can contain other [!INCLUDE[TLA2#tla_ui#plural](../../../../includes/tla2sharptla-uisharpplural-md.md)], such as <xref:System.Windows.Controls.UserControl>. The following code shows the host view of the contract, implemented as the `WPFAddInHostView` class.  
+## Implementing the Host View Pipeline Segment
+
+In this model, the host application typically expects the host view to be a <xref:System.Windows.FrameworkElement> subclass. The host-side adapter must convert the <xref:System.AddIn.Contract.INativeHandleContract> to a <xref:System.Windows.FrameworkElement> after the <xref:System.AddIn.Contract.INativeHandleContract> crosses the isolation boundary. Because a method isn't being called by the host application to get the <xref:System.Windows.FrameworkElement>, the host view must "return" the <xref:System.Windows.FrameworkElement> by containing it. Consequently, the host view must derive from a subclass of <xref:System.Windows.FrameworkElement> that can contain other UIs, such as <xref:System.Windows.Controls.UserControl>. The following code shows the host view of the contract, implemented as the `WPFAddInHostView` class.  
+
+[!code-csharp[WPFAddInHostView class](~/samples/snippets/csharp/VS_Snippets_Wpf/SimpleAddInIsAUISample/CSharp/HostViews/WPFAddInHostView.cs#HostViewCode)]
+[!code-vb[WPFAddInHostView class](~/samples/snippets/visualbasic/VS_Snippets_Wpf/SimpleAddInIsAUISample/VisualBasic/HostViews/WPFAddInHostView.vb#HostViewCode)]
 
 <a name="HostSideAdapter"></a>   
-## Implementing the Host-Side Adapter Pipeline Segment  
- While the contract is an <xref:System.AddIn.Contract.INativeHandleContract>, the host application expects a <xref:System.Windows.Controls.UserControl> (as specified by the host view). Consequently, the <xref:System.AddIn.Contract.INativeHandleContract> must be converted to a <xref:System.Windows.FrameworkElement> after crossing the isolation boundary, before being set as content of the host view (which derives from <xref:System.Windows.Controls.UserControl>).  
+## Implementing the Host-Side Adapter Pipeline Segment
+
+While the contract is an <xref:System.AddIn.Contract.INativeHandleContract>, the host application expects a <xref:System.Windows.Controls.UserControl> (as specified by the host view). Consequently, the <xref:System.AddIn.Contract.INativeHandleContract> must be converted to a <xref:System.Windows.FrameworkElement> after crossing the isolation boundary, before being set as content of the host view (which derives from <xref:System.Windows.Controls.UserControl>).  
 
- This work is performed by the host-side adapter, as shown in the following code.  
+This work is performed by the host-side adapter, as shown in the following code.  
 
- As you can see, the host-side adapter acquires the <xref:System.AddIn.Contract.INativeHandleContract> by calling the add-in-side adapter's <xref:System.AddIn.Pipeline.ContractBase.QueryContract%2A> method (this is the point where the <xref:System.AddIn.Contract.INativeHandleContract> crosses the isolation boundary).  
+[!code-csharp[Host-side adapter](~/samples/snippets/csharp/VS_Snippets_Wpf/SimpleAddInIsAUISample/CSharp/HostSideAdapters/WPFAddIn_ContractToViewHostSideAdapter.cs#HostSideAdapterCode)]
+[!code-vb[Host-side adapter](~/samples/snippets/visualbasic/VS_Snippets_Wpf/SimpleAddInIsAUISample/VisualBasic/HostSideAdapters/WPFAddIn_ContractToViewHostSideAdapter.vb#HostSideAdapterCode)]
+
+As you can see, the host-side adapter acquires the <xref:System.AddIn.Contract.INativeHandleContract> by calling the add-in-side adapter's <xref:System.AddIn.Pipeline.ContractBase.QueryContract%2A> method (this is the point where the <xref:System.AddIn.Contract.INativeHandleContract> crosses the isolation boundary).  
 
- The host-side adapter then converts the <xref:System.AddIn.Contract.INativeHandleContract> to a <xref:System.Windows.FrameworkElement> by calling <xref:System.AddIn.Pipeline.FrameworkElementAdapters.ContractToViewAdapter%2A>. Finally, the <xref:System.Windows.FrameworkElement> is set as the content of the host view.  
+The host-side adapter then converts the <xref:System.AddIn.Contract.INativeHandleContract> to a <xref:System.Windows.FrameworkElement> by calling <xref:System.AddIn.Pipeline.FrameworkElementAdapters.ContractToViewAdapter%2A>. Finally, the <xref:System.Windows.FrameworkElement> is set as the content of the host view.  
 
 <a name="AddIn"></a>   
-## Implementing the Add-In  
- With the add-in-side adapter and add-in view in place, the add-in can be implemented by deriving from the add-in view, as shown in the following code.  
+## Implementing the Add-In
+
+With the add-in-side adapter and add-in view in place, the add-in can be implemented by deriving from the add-in view, as shown in the following code.  
 
- From this example, you can see one interesting benefit of this model: add-in developers only need to implement the add-in (since it is the UI as well), rather than both an add-in class and an add-in UI.  
+[!code-csharp[Add-in implementation](~/samples/snippets/csharp/VS_Snippets_Wpf/SimpleAddInIsAUISample/CSharp/WPFAddIn1/AddInUI.xaml.cs#AddInCodeBehind)]
+[!code-vb[Add-in implementation](~/samples/snippets/visualbasic/VS_Snippets_Wpf/SimpleAddInIsAUISample/VisualBasic/WPFAddIn1/AddInUI.xaml.vb#AddInCodeBehind)]
+
+From this example, you can see one interesting benefit of this model: add-in developers only need to implement the add-in (since it is the UI as well), rather than both an add-in class and an add-in UI.  
 
-<a name="HostApp"></a>   
-## Implementing the Host Application  
- With the host-side adapter and host view created, the host application can use the .NET Framework add-in model to open the pipeline and acquire a host view of the add-in. These steps are shown in the following code.  
+<a name="HostApp"></a>
+## Implementing the Host Application
+
+With the host-side adapter and host view created, the host application can use the .NET Framework add-in model to open the pipeline and acquire a host view of the add-in. These steps are shown in the following code.  
+
+[!code-csharp[Acquiring a host view of the add-in](~/samples/snippets/csharp/VS_Snippets_Wpf/SimpleAddInIsAUISample/CSharp/Host/MainWindow.xaml.cs#GetUICode)]
+[!code-vb[Acquiring a host view of the add-in](~/samples/snippets/visualbasic/VS_Snippets_Wpf/SimpleAddInIsAUISample/VisualBasic/Host/MainWindow.xaml.vb#GetUICode)]
 
- The host application uses typical .NET Framework add-in model code to activate the add-in, which implicitly returns the host view to the host application. The host application subsequently displays the host view (which is a <xref:System.Windows.Controls.UserControl>) from a <xref:System.Windows.Controls.Grid>.  
+The host application uses typical .NET Framework add-in model code to activate the add-in, which implicitly returns the host view to the host application. The host application subsequently displays the host view (which is a <xref:System.Windows.Controls.UserControl>) from a <xref:System.Windows.Controls.Grid>.  
 
  The code for processing interactions with the add-in UI runs in the add-in's application domain. These interactions include the following: