如何创建一个作为 UI 的 Add-In

项目
12/18/2024

此示例演示如何创建由 WPF 独立应用程序托管的 Windows Presentation Foundation（WPF）加载项。

这个加载项是基于 WPF 用户控件的 UI。用户控件的内容是单击后显示消息框的单个按钮。 WPF 独立应用程序将外接程序 UI 作为主应用程序窗口的内容托管。

先决条件

此示例重点介绍 .NET Framework 插件模型中的 WPF 扩展以启用该场景，并假设以下情况：

了解 .NET Framework 外接程序模型，包括管道、外接程序和宿主开发。如果您不熟悉这些概念，请参阅插件和扩展性。有关演示管道、加载项和主机应用程序的实现的教程，请参阅演练：创建可扩展应用程序。
对 .NET Framework 插件模型的 WPF 扩展有了解。请参阅 WPF Add-Ins 概述。

例

若要创建作为 WPF UI 的外接程序，需要每个管道段、加载项和主机应用程序的特定代码。

实施合同管道部分

当加载项是一个用户界面时，加载项的合同必须实现 INativeHandleContract。在此示例中，IWPFAddInContract 实现 INativeHandleContract，如以下代码所示。

using System.AddIn.Contract;
using System.AddIn.Pipeline;

namespace Contracts
{
    /// <summary>
    /// Defines the services that an add-in will provide to a host application.
    /// In this case, the add-in is a UI.
    /// </summary>
    [AddInContract]
    public interface IWPFAddInContract : INativeHandleContract {}
}


Imports System.AddIn.Contract
Imports System.AddIn.Pipeline

Namespace Contracts
    ''' <summary>
    ''' Defines the services that an add-in will provide to a host application.
    ''' In this case, the add-in is a UI.
    ''' </summary>
    <AddInContract>
    Public Interface IWPFAddInContract
        Inherits INativeHandleContract
        Inherits IContract
    End Interface
End Namespace

实现 Add-In 视图管道段

由于外接程序作为 FrameworkElement 类型的子类实现，因此外接程序视图还必须成为 FrameworkElement的一个子类。以下代码显示了协定的插件视图，该视图作为 WPFAddInView 类实现。

using System.AddIn.Pipeline;
using System.Windows.Controls;

namespace AddInViews
{
    /// <summary>
    /// Defines the add-in's view of the contract.
    /// </summary>
    [AddInBase]
    public class WPFAddInView : UserControl { }
}


Imports System.AddIn.Pipeline
Imports System.Windows.Controls

Namespace AddInViews
    ''' <summary>
    ''' Defines the add-in's view of the contract.
    ''' </summary>
    <AddInBase>
    Public Class WPFAddInView
        Inherits UserControl
    End Class
End Namespace

此处，外接程序视图派生自 UserControl。因此，外接程序 UI 还应派生自 UserControl。

实现 Add-In-Side 适配器管道段

虽然合同是 INativeHandleContract，但外接程序则是 FrameworkElement（由外接程序视图管道段指定）。因此，在跨越隔离边界之前，必须将 FrameworkElement 转换为 INativeHandleContract。加载项端适配器通过调用 ViewToContractAdapter来执行此工作，如以下代码所示。

using System;
using System.AddIn.Contract;
using System.AddIn.Pipeline;
using System.Security.Permissions;

using AddInViews;
using Contracts;

namespace AddInSideAdapters
{
    /// <summary>
    /// Adapts the add-in's view of the contract to the add-in contract
    /// </summary>
    [AddInAdapter]
    public class WPFAddIn_ViewToContractAddInSideAdapter : ContractBase, IWPFAddInContract
    {
        WPFAddInView wpfAddInView;

        public WPFAddIn_ViewToContractAddInSideAdapter(WPFAddInView wpfAddInView)
        {
            // Adapt the add-in view of the contract (WPFAddInView)
            // to the contract (IWPFAddInContract)
            this.wpfAddInView = wpfAddInView;
        }

        /// <summary>
        /// ContractBase.QueryContract must be overridden to:
        /// * Safely return a window handle for an add-in UI to the host
        ///   application's application.
        /// * Enable tabbing between host application UI and add-in UI, in the
        ///   "add-in is a UI" scenario.
        /// </summary>
        public override IContract QueryContract(string contractIdentifier)
        {
            if (contractIdentifier.Equals(typeof(INativeHandleContract).AssemblyQualifiedName))
            {
                return FrameworkElementAdapters.ViewToContractAdapter(this.wpfAddInView);
            }

            return base.QueryContract(contractIdentifier);
        }

        /// <summary>
        /// GetHandle is called by the WPF add-in model from the host application's
        /// application domain to get the window handle for an add-in UI from the
        /// add-in's application domain. GetHandle is called if a window handle isn't
        /// returned by other means, that is, overriding ContractBase.QueryContract,
        /// as shown above.
        /// NOTE: This method requires UnmanagedCodePermission to be called
        ///       (full-trust by default), to prevent illegal window handle
        ///       access in partially trusted scenarios. If the add-in could
        ///       run in a partially trusted application domain
        ///       (eg AddInSecurityLevel.Internet), you can safely return a window
        ///       handle by overriding ContractBase.QueryContract, as shown above.
        /// </summary>
        public IntPtr GetHandle()
        {
            return FrameworkElementAdapters.ViewToContractAdapter(this.wpfAddInView).GetHandle();
        }
    }
}


Imports System
Imports System.AddIn.Contract
Imports System.AddIn.Pipeline
Imports System.Security.Permissions

Imports AddInViews
Imports Contracts

Namespace AddInSideAdapters
    ''' <summary>
    ''' Adapts the add-in's view of the contract to the add-in contract
    ''' </summary>
    <AddInAdapter>
    Public Class WPFAddIn_ViewToContractAddInSideAdapter
        Inherits ContractBase
        Implements IWPFAddInContract

        Private wpfAddInView As WPFAddInView

        Public Sub New(ByVal wpfAddInView As WPFAddInView)
            ' Adapt the add-in view of the contract (WPFAddInView) 
            ' to the contract (IWPFAddInContract)
            Me.wpfAddInView = wpfAddInView
        End Sub

        ''' <summary>
        ''' ContractBase.QueryContract must be overridden to:
        ''' * Safely return a window handle for an add-in UI to the host 
        '''   application's application.
        ''' * Enable tabbing between host application UI and add-in UI, in the
        '''   "add-in is a UI" scenario.
        ''' </summary>
        Public Overrides Function QueryContract(ByVal contractIdentifier As String) As IContract
            If contractIdentifier.Equals(GetType(INativeHandleContract).AssemblyQualifiedName) Then
                Return FrameworkElementAdapters.ViewToContractAdapter(Me.wpfAddInView)
            End If

            Return MyBase.QueryContract(contractIdentifier)
        End Function

        ''' <summary>
        ''' GetHandle is called by the WPF add-in model from the host application's 
        ''' application domain to get the window handle for an add-in UI from the 
        ''' add-in's application domain. GetHandle is called if a window handle isn't 
        ''' returned by other means, that is, overriding ContractBase.QueryContract, 
        ''' as shown above.
        ''' </summary>
        Public Function GetHandle() As IntPtr Implements INativeHandleContract.GetHandle
            Return FrameworkElementAdapters.ViewToContractAdapter(Me.wpfAddInView).GetHandle()
        End Function

    End Class
End Namespace

在外接程序返回 UI 的外接程序模型中（请参阅创建返回 UI的 Add-In），外接程序适配器通过调用 ViewToContractAdapter将 FrameworkElement 转换为 INativeHandleContract。 ViewToContractAdapter 也必须在此模型中调用，不过你需要实现一个方法，用来编写调用它的代码。为此，您需要重写 QueryContract，并实现调用 ViewToContractAdapter 的代码，前提是调用 QueryContract 的代码期待 INativeHandleContract。在这种情况下，调用方将是主机端适配器，该适配器将在后面的章节中介绍。

注意

您还需要在此模型中重写 QueryContract，以启用在主机应用程序 UI 和外接程序 UI 之间的切换。有关详细信息，请参阅 WPF Add-Ins 概述中的“WPF Add-In 限制”。

由于外接程序端适配器实现派生自 INativeHandleContract的接口，因此还需要实现 GetHandle，尽管在重写 QueryContract 时会忽略此接口。

主视图管道段的实现

在此模型中，主机应用程序通常要求主机视图是 FrameworkElement 子类。在 INativeHandleContract 越过隔离边界后，主机端适配器必须将 INativeHandleContract 转换为 FrameworkElement。由于主机应用程序未调用方法来获取 FrameworkElement，主机视图必须通过包含的方式将 FrameworkElement "返回"。因此，主机视图必须派生自可以包含其他 UI（如 UserControl）的 FrameworkElement 子类。以下代码显示了作为 WPFAddInHostView 类实现的协定的主机视图。

using System.Windows.Controls;

namespace HostViews
{
    /// <summary>
    /// Defines the host's view of the add-in
    /// </summary>
    public class WPFAddInHostView : UserControl { }
}


Imports System.Windows.Controls

Namespace HostViews
    ''' <summary>
    ''' Defines the host's view of the add-in
    ''' </summary>
    Public Class WPFAddInHostView
        Inherits UserControl
    End Class
End Namespace

实现 Host-Side 适配器管道段

虽然合同是 INativeHandleContract，但主应用程序期望为 UserControl（由主机视图指定）。因此，在越过隔离边界后，必须将 INativeHandleContract 转换为 FrameworkElement，然后再设置为主机视图的内容（该内容派生自 UserControl）。

此工作由主机端适配器执行，如以下代码所示。

using System.AddIn.Contract;
using System.AddIn.Pipeline;
using System.Windows;

using Contracts;
using HostViews;

namespace HostSideAdapters
{
    /// <summary>
    /// Adapts the add-in contract to the host's view of the add-in
    /// </summary>
    [HostAdapter]
    public class WPFAddIn_ContractToViewHostSideAdapter : WPFAddInHostView
    {
        IWPFAddInContract wpfAddInContract;
        ContractHandle wpfAddInContractHandle;

        public WPFAddIn_ContractToViewHostSideAdapter(IWPFAddInContract wpfAddInContract)
        {
            // Adapt the contract (IWPFAddInContract) to the host application's
            // view of the contract (WPFAddInHostView)
            this.wpfAddInContract = wpfAddInContract;

            // Prevent the reference to the contract from being released while the
            // host application uses the add-in
            this.wpfAddInContractHandle = new ContractHandle(wpfAddInContract);

            // Convert the INativeHandleContract for the add-in UI that was passed
            // from the add-in side of the isolation boundary to a FrameworkElement
            string aqn = typeof(INativeHandleContract).AssemblyQualifiedName;
            INativeHandleContract inhc = (INativeHandleContract)wpfAddInContract.QueryContract(aqn);
            FrameworkElement fe = (FrameworkElement)FrameworkElementAdapters.ContractToViewAdapter(inhc);

            // Add FrameworkElement (which displays the UI provided by the add-in) as
            // content of the view (a UserControl)
            this.Content = fe;
        }
    }
}


Imports System.AddIn.Contract
Imports System.AddIn.Pipeline
Imports System.Windows

Imports Contracts
Imports HostViews

Namespace HostSideAdapters
    ''' <summary>
    ''' Adapts the add-in contract to the host's view of the add-in
    ''' </summary>
    <HostAdapter>
    Public Class WPFAddIn_ContractToViewHostSideAdapter
        Inherits WPFAddInHostView
        Private wpfAddInContract As IWPFAddInContract
        Private wpfAddInContractHandle As ContractHandle

        Public Sub New(ByVal wpfAddInContract As IWPFAddInContract)
            ' Adapt the contract (IWPFAddInContract) to the host application's
            ' view of the contract (WPFAddInHostView)
            Me.wpfAddInContract = wpfAddInContract

            ' Prevent the reference to the contract from being released while the
            ' host application uses the add-in
            Me.wpfAddInContractHandle = New ContractHandle(wpfAddInContract)

            ' Convert the INativeHandleContract for the add-in UI that was passed 
            ' from the add-in side of the isolation boundary to a FrameworkElement
            Dim aqn As String = GetType(INativeHandleContract).AssemblyQualifiedName
            Dim inhc As INativeHandleContract = CType(wpfAddInContract.QueryContract(aqn), INativeHandleContract)
            Dim fe As FrameworkElement = CType(FrameworkElementAdapters.ContractToViewAdapter(inhc), FrameworkElement)

            ' Add FrameworkElement (which displays the UI provided by the add-in) as
            ' content of the view (a UserControl)
            Me.Content = fe
        End Sub
    End Class
End Namespace

您可以看到，主机侧适配器通过调用加载项侧适配器的 QueryContract 方法来获取 INativeHandleContract（这是 INativeHandleContract 跨越隔离边界的点）。

然后，主机端适配器通过调用 ContractToViewAdapter将 INativeHandleContract 转换为 FrameworkElement。最后，将 FrameworkElement 设置为主机视图的内容。

实现 Add-In

使用外接程序适配器和外接程序视图设置完毕后，可以通过从外接程序视图派生来实现外接程序，如以下代码所示。

using System.AddIn;
using System.Windows;

using AddInViews;

namespace WPFAddIn1
{
    /// <summary>
    /// Implements the add-in by deriving from WPFAddInView
    /// </summary>
    [AddIn("WPF Add-In 1")]
    public partial class AddInUI : WPFAddInView
    {
        public AddInUI()
        {
            InitializeComponent();
        }

        void clickMeButton_Click(object sender, RoutedEventArgs e)
        {
            MessageBox.Show("Hello from WPFAddIn1");
        }
    }
}


Imports System.AddIn
Imports System.Windows

Imports AddInViews

Namespace WPFAddIn1
    ''' <summary>
    ''' Implements the add-in by deriving from WPFAddInView
    ''' </summary>
    <AddIn("WPF Add-In 1")>
    Partial Public Class AddInUI
        Inherits WPFAddInView
        Public Sub New()
            InitializeComponent()
        End Sub

        Private Sub clickMeButton_Click(ByVal sender As Object, ByVal e As RoutedEventArgs)
            MessageBox.Show("Hello from WPFAddIn1")
        End Sub
    End Class
End Namespace

在此示例中，您可以看到此模型的一个有趣优势：外接程序开发人员只需实现外接程序（因为它也是用户界面），无需分别实现外接程序类和外接程序用户界面。

实现宿主应用程序

创建主机端适配器和主机视图后，主机应用程序可以使用 .NET Framework 外接程序模型打开管道并获取外接程序的主机视图。以下步骤显示在以下代码中。

// Get add-in pipeline folder (the folder in which this application was launched from)
string appPath = Environment.CurrentDirectory;

// Rebuild visual add-in pipeline
string[] warnings = AddInStore.Rebuild(appPath);
if (warnings.Length > 0)
{
    string msg = "Could not rebuild pipeline:";
    foreach (string warning in warnings) msg += "\n" + warning;
    MessageBox.Show(msg);
    return;
}

// Activate add-in with Internet zone security isolation
Collection<AddInToken> addInTokens = AddInStore.FindAddIns(typeof(WPFAddInHostView), appPath);
AddInToken wpfAddInToken = addInTokens[0];
this.wpfAddInHostView = wpfAddInToken.Activate<WPFAddInHostView>(AddInSecurityLevel.Internet);

// Display add-in UI
this.addInUIHostGrid.Children.Add(this.wpfAddInHostView);

' Get add-in pipeline folder (the folder in which this application was launched from)
Dim appPath As String = Environment.CurrentDirectory

' Rebuild visual add-in pipeline
Dim warnings() As String = AddInStore.Rebuild(appPath)
If warnings.Length > 0 Then
    Dim msg As String = "Could not rebuild pipeline:"
    For Each warning As String In warnings
        msg &= vbLf & warning
    Next warning
    MessageBox.Show(msg)
    Return
End If

' Activate add-in with Internet zone security isolation
Dim addInTokens As Collection(Of AddInToken) = AddInStore.FindAddIns(GetType(WPFAddInHostView), appPath)
Dim wpfAddInToken As AddInToken = addInTokens(0)
Me.wpfAddInHostView = wpfAddInToken.Activate(Of WPFAddInHostView)(AddInSecurityLevel.Internet)

' Display add-in UI
Me.addInUIHostGrid.Children.Add(Me.wpfAddInHostView)

主机应用程序使用典型的 .NET Framework 外接程序模型代码来激活外接程序，该外接程序隐式将主机视图返回给主机应用程序。主机应用程序随后从 Grid显示主机视图（即 UserControl）。

用于处理与外接程序 UI 交互的代码在外接程序的应用程序域中运行。这些交互包括：

处理 Button Click 事件。
显示 MessageBox。

此活动与主机应用程序完全隔离。

通过