演练：创建菜单提供程序

项目
08/12/2011

本演练演示如何为 Windows Presentation Foundation (WPF) 自定义控件创建设计时菜单提供程序。可以使用此快捷菜单项在自定义按钮控件上设置 Background 属性的值。有关完整的代码清单，请参见 WPF Designer Extensibility Samples（WPF 设计器扩展性示例）站点上的“上下文菜单提供程序”示例。

在本演练中，您将执行下列任务：

创建一个 WPF 自定义控件库项目。
为设计时元数据创建一个单独的程序集。
实现菜单提供程序。
在设计时使用控件。

完成本演练后，您将知道如何为自定义控件创建菜单提供程序。

提示

显示的对话框和菜单命令可能会与“帮助”中的描述不同，具体取决于您现用的设置或版本。若要更改设置，请在“工具”菜单上选择“导入和导出设置”。有关更多信息，请参见使用设置。

系统必备

您需要以下组件来完成本演练：

Visual Studio 2010.

创建自定义控件

第一步是为自定义控件创建项目。该控件是一个带有少量设计时代码的简单按钮，该按钮使用 GetIsInDesignMode 方法来实现设计时行为。

创建自定义控件

使用 Visual Basic 或 Visual C# 创建一个名为 CustomControlLibrary 的新 WPF 自定义控件库项目。

CustomControl1 的代码在“代码编辑器”中打开。
在**“解决方案资源管理器”中，将代码文件的名称更改为 ButtonWithDesignTime.cs 或 ButtonWithDesignTime.vb。如果出现消息框，询问是否对此项目中的所有引用执行重命名操作，请单击“是”**。
在“代码编辑器”中打开 ButtonWithDesignTime.cs 或 ButtonWithDesignTime.vb。

用下面的代码替换自动生成的代码。此代码从 Button 继承而来，当按钮出现在设计器中时，将显示文本“已激活设计模式”。

Imports System
Imports System.Collections.Generic
Imports System.Text
Imports System.Windows.Controls
Imports System.Windows.Media
Imports System.ComponentModel

Public Class ButtonWithDesignTime
    Inherits Button

    Public Sub New()
        ' The GetIsInDesignMode check and the following design-time 
        ' code are optional and shown only for demonstration.
        If DesignerProperties.GetIsInDesignMode(Me) Then
            Content = "Design mode active"
        End If

    End Sub
End Class

using System;
using System.Collections.Generic;
using System.Text;
using System.Windows.Controls;
using System.Windows.Media;
using System.ComponentModel;

namespace CustomControlLibrary
{
    public class ButtonWithDesignTime : Button
    {
        public ButtonWithDesignTime()
        {
            // The GetIsInDesignMode check and the following design-time 
            // code are optional and shown only for demonstration.
            if (DesignerProperties.GetIsInDesignMode(this))
            {
                Content = "Design mode active";
            }
        }
    }
}

将项目的输出路径设置为“bin\”。
生成解决方案。

创建设计时元数据程序集

设计时代码在特定元数据程序集中部署。对于本演练，上下文菜单实现在一个名为 CustomControlLibrary.VisualStudio.Design 的程序集中部署。有关更多信息，请参见提供设计时元数据。

创建设计时元数据程序集

使用 Visual Basic 或 Visual C# 为解决方案添加一个名为 CustomControlLibrary.VisualStudio.Design 的新类库项目。
将项目的输出路径设置为“.. \CustomControlLibrary\bin\”。这样可使控件的程序集与元数据程序集位于同一文件夹中，从而可为设计器启用元数据发现。
添加对下列 WPF 程序集的引用。
- PresentationCore
- PresentationFramework
- System.Xaml
- WindowsBase
添加对下列 WPF 设计器程序集的引用。
- Microsoft.Windows.Design.Extensibility
- Microsoft.Windows.Design.Interaction
添加对 CustomControlLibrary 项目的引用。
在**“解决方案资源管理器”中，将 Class1 代码文件的名称更改为 Metadata.cs 或 Metadata.vb。如果出现消息框，询问是否对此项目中的所有引用执行重命名操作，请单击“是”**。

用下面的代码替换自动生成的代码。此代码将创建一个将自定义设计时实现附加到 ButtonWithDesignTime 类的 AttributeTable。

Imports System
Imports System.Collections.Generic
Imports System.Text
Imports System.ComponentModel
Imports System.Windows.Media
Imports System.Windows.Controls
Imports System.Windows
Imports CustomControlLibrary
Imports Microsoft.Windows.Design.Features
Imports Microsoft.Windows.Design.Metadata
'Imports CustomControlLibrary.VisualStudio.Design.Slid

' The ProvideMetadata assembly-level attribute indicates to designers
' that this assembly contains a class that provides an attribute table. 
<Assembly: ProvideMetadata(GetType(CustomControlLibrary.VisualStudio.Design.Metadata))> 

' Container for any general design-time metadata to initialize.
' Designers look for a type in the design-time assembly that 
' implements IProvideAttributeTable. If found, designers instantiate
' this class and access its AttributeTable property automatically.
Friend Class Metadata
    Implements IProvideAttributeTable

    ' Accessed by the designer to register any design-time metadata.
    Public ReadOnly Property AttributeTable() As AttributeTable _
        Implements IProvideAttributeTable.AttributeTable
        Get
            Dim builder As New AttributeTableBuilder()

            ' Add the menu provider to the design-time metadata.
            builder.AddCustomAttributes(GetType(ButtonWithDesignTime), _
                                        New FeatureAttribute(GetType(CustomContextMenuProvider)))

            Return builder.CreateTable()
        End Get
    End Property
End Class

using System;
using System.Collections.Generic;
using System.Text;
using System.ComponentModel;
using System.Windows.Media;
using System.Windows.Controls;
using System.Windows;

using CustomControlLibrary;
using Microsoft.Windows.Design.Features;
using Microsoft.Windows.Design.Metadata;
using CustomControlLibrary.VisualStudio.Design;

// The ProvideMetadata assembly-level attribute indicates to designers
// that this assembly contains a class that provides an attribute table. 
[assembly: ProvideMetadata(typeof(CustomControlLibrary.VisualStudio.Design.Metadata))]
namespace CustomControlLibrary.VisualStudio.Design
{
    // Container for any general design-time metadata to initialize.
    // Designers look for a type in the design-time assembly that 
    // implements IProvideAttributeTable. If found, designers instantiate 
    // this class and access its AttributeTable property automatically.
    internal class Metadata : IProvideAttributeTable
    {
        // Accessed by the designer to register any design-time metadata.
        public AttributeTable AttributeTable
        {
            get
            {
                AttributeTableBuilder builder = new AttributeTableBuilder();

                // Add the menu provider to the design-time metadata.
                builder.AddCustomAttributes(
                    typeof(ButtonWithDesignTime),
                    new FeatureAttribute(typeof(CustomContextMenuProvider)));

                return builder.CreateTable(); 
            }
        }
    }
}

保存解决方案。

实现菜单提供程序

菜单提供程序在名为 CustomContextMenuProvider 的类型中的实现。通过提供的 MenuAction，可以在设计时设置控件的 Background 属性。

实现菜单提供程序

向 CustomControlLibrary.VisualStudio.Design 项目中添加一个名为 CustomContextMenuProvider 的新类。

在 CustomContextMenuProvider 的代码编辑器中，用下面的代码替换自动生成的代码。此代码实现提供自定义 MenuAction 的 PrimarySelectionContextMenuProvider。

Imports System
Imports System.Collections.Generic
Imports System.Text
Imports Microsoft.Windows.Design.Interaction
Imports System.Windows
Imports Microsoft.Windows.Design.Model
Imports System.Windows.Controls
Imports System.Windows.Media

' The CustomContextMenuProvider class provides two context menu items
' at design time. These are implemented with the MenuAction class.
Class CustomContextMenuProvider
    Inherits PrimarySelectionContextMenuProvider

    Private setBackgroundToBlueMenuAction As MenuAction
    Private clearBackgroundMenuAction As MenuAction

    ' The provider's constructor sets up the MenuAction objects 
    ' and the the MenuGroup which holds them.
    Public Sub New()

        ' Set up the MenuAction which sets the control's 
        ' background to Blue.
        setBackgroundToBlueMenuAction = New MenuAction("Blue")
        setBackgroundToBlueMenuAction.Checkable = True
        AddHandler setBackgroundToBlueMenuAction.Execute, AddressOf SetBackgroundToBlue_Execute

        ' Set up the MenuAction which sets the control's 
        ' background to its default value.
        clearBackgroundMenuAction = New MenuAction("Cleared")
        clearBackgroundMenuAction.Checkable = True
        AddHandler clearBackgroundMenuAction.Execute, AddressOf ClearBackground_Execute

        ' Set up the MenuGroup which holds the MenuAction items.
        Dim backgroundFlyoutGroup As New MenuGroup("SetBackgroundsGroup", "Set Background")

        ' If HasDropDown is false, the group appears inline, 
        ' instead of as a flyout. Set to true.
        backgroundFlyoutGroup.HasDropDown = True
        backgroundFlyoutGroup.Items.Add(setBackgroundToBlueMenuAction)
        backgroundFlyoutGroup.Items.Add(clearBackgroundMenuAction)
        Me.Items.Add(backgroundFlyoutGroup)

        ' The UpdateItemStatus event is raised immediately before 
        ' this provider shows its tabs, which provides the opportunity 
        ' to set states.
        AddHandler UpdateItemStatus, AddressOf CustomContextMenuProvider_UpdateItemStatus

    End Sub

    ' The following method handles the UpdateItemStatus event.
    ' It sets the MenuAction states according to the state
    ' of the control's Background property. This method is
    ' called before the context menu is shown.
    Sub CustomContextMenuProvider_UpdateItemStatus( _
        ByVal sender As Object, _
        ByVal e As MenuActionEventArgs)

        ' Turn everything on, and then based on the value 
        ' of the BackgroundProperty, selectively turn some off.
        clearBackgroundMenuAction.Checked = False
        clearBackgroundMenuAction.Enabled = True
        setBackgroundToBlueMenuAction.Checked = False
        setBackgroundToBlueMenuAction.Enabled = True

        ' Get a ModelItem which represents the selected control. 
        Dim selectedControl As ModelItem = _
            e.Selection.PrimarySelection

        ' Get the value of the Background property from the ModelItem.
        Dim backgroundProperty As ModelProperty = _
            selectedControl.Properties("Background")

        ' Set the MenuAction items appropriately.
        If Not backgroundProperty.IsSet Then
            clearBackgroundMenuAction.Checked = True
            clearBackgroundMenuAction.Enabled = False
        ElseIf backgroundProperty.ComputedValue.Equals(Brushes.Blue) Then
            setBackgroundToBlueMenuAction.Checked = True
            setBackgroundToBlueMenuAction.Enabled = False
        End If

    End Sub

    ' The following method handles the Execute event. 
    ' It sets the Background property to its default value.
    Sub ClearBackground_Execute( _
        ByVal sender As Object, _
        ByVal e As MenuActionEventArgs)

        Dim selectedControl As ModelItem = e.Selection.PrimarySelection
        selectedControl.Properties("Background").ClearValue()

    End Sub

    ' The following method handles the Execute event. 
    ' It sets the Background property to Brushes.Blue.
    Sub SetBackgroundToBlue_Execute( _
        ByVal sender As Object, _
        ByVal e As MenuActionEventArgs)

        Dim selectedControl As ModelItem = e.Selection.PrimarySelection
        selectedControl.Properties("Background").SetValue(Brushes.Blue)

    End Sub

End Class

using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.Windows.Design.Interaction;
using System.Windows;
using Microsoft.Windows.Design.Model;
using System.Windows.Controls;
using System.Windows.Media;

namespace CustomControlLibrary.VisualStudio.Design
{
    // The CustomContextMenuProvider class provides two context menu items
    // at design time. These are implemented with the MenuAction class.
    class CustomContextMenuProvider : PrimarySelectionContextMenuProvider
    {
        private MenuAction setBackgroundToBlueMenuAction;
        private MenuAction clearBackgroundMenuAction;

        // The provider's constructor sets up the MenuAction objects 
        // and the the MenuGroup which holds them.
        public CustomContextMenuProvider()
        {   
            // Set up the MenuAction which sets the control's 
            // background to Blue.
            setBackgroundToBlueMenuAction = new MenuAction("Blue");
            setBackgroundToBlueMenuAction.Checkable = true;
            setBackgroundToBlueMenuAction.Execute += 
                new EventHandler<MenuActionEventArgs>(SetBackgroundToBlue_Execute);

            // Set up the MenuAction which sets the control's 
            // background to its default value.
            clearBackgroundMenuAction = new MenuAction("Cleared");
            clearBackgroundMenuAction.Checkable = true;
            clearBackgroundMenuAction.Execute += 
                new EventHandler<MenuActionEventArgs>(ClearBackground_Execute);

            // Set up the MenuGroup which holds the MenuAction items.
            MenuGroup backgroundFlyoutGroup = 
                new MenuGroup("SetBackgroundsGroup", "Set Background");

            // If HasDropDown is false, the group appears inline, 
            // instead of as a flyout. Set to true.
            backgroundFlyoutGroup.HasDropDown = true;
            backgroundFlyoutGroup.Items.Add(setBackgroundToBlueMenuAction);
            backgroundFlyoutGroup.Items.Add(clearBackgroundMenuAction);
            this.Items.Add(backgroundFlyoutGroup);

            // The UpdateItemStatus event is raised immediately before 
            // this provider shows its tabs, which provides the opportunity 
            // to set states.
            UpdateItemStatus += 
                new EventHandler<MenuActionEventArgs>(
                    CustomContextMenuProvider_UpdateItemStatus);
        }

        // The following method handles the UpdateItemStatus event.
        // It sets the MenuAction states according to the state
        // of the control's Background property. This method is
        // called before the context menu is shown.
        void CustomContextMenuProvider_UpdateItemStatus(
            object sender, 
            MenuActionEventArgs e)
        {
            // Turn everything on, and then based on the value 
            // of the BackgroundProperty, selectively turn some off.
            clearBackgroundMenuAction.Checked = false;
            clearBackgroundMenuAction.Enabled = true;
            setBackgroundToBlueMenuAction.Checked = false;
            setBackgroundToBlueMenuAction.Enabled = true;

            // Get a ModelItem which represents the selected control. 
            ModelItem selectedControl = e.Selection.PrimarySelection;

            // Get the value of the Background property from the ModelItem.
            ModelProperty backgroundProperty = 
                selectedControl.Properties["Background"];

            // Set the MenuAction items appropriately.
            if (!backgroundProperty.IsSet)
            {
                clearBackgroundMenuAction.Checked = true;
                clearBackgroundMenuAction.Enabled = false;
            }
            else if (backgroundProperty.ComputedValue == Brushes.Blue)
            {
                setBackgroundToBlueMenuAction.Checked = true;
                setBackgroundToBlueMenuAction.Enabled = false;
            }
        }

        // The following method handles the Execute event. 
        // It sets the Background property to its default value.
        void ClearBackground_Execute(
            object sender, 
            MenuActionEventArgs e)
        {
            ModelItem selectedControl = e.Selection.PrimarySelection;
            selectedControl.Properties["Background"].ClearValue();
        }

        // The following method handles the Execute event. 
        // It sets the Background property to Brushes.Blue.
        void SetBackgroundToBlue_Execute(
            object sender, 
            MenuActionEventArgs e)
        {
            ModelItem selectedControl = e.Selection.PrimarySelection;
            selectedControl.Properties["Background"].SetValue(Brushes.Blue);
        }
    }
}

生成解决方案。

测试设计时实现

可以像使用任何其他 WPF 控件一样使用 ButtonWithDesignTime 控件。 WPF 设计器处理所有设计时对象的创建。

测试设计时实现

使用 Visual Basic 或 Visual C# 为解决方案添加一个名为 DemoApplication 的新 WPF 应用程序项目。

MainWindow.xaml 将在 WPF 设计器中打开。
添加对 CustomControlLibrary 项目的引用。

在 XAML 视图中，用以下 XAML 替换自动生成的 XAML。此 XAML 将添加对 CustomControlLibrary 命名空间的引用并添加 ButtonWithDesignTime 自定义控件。该按钮出现在“设计”视图中，并显示文本“已激活设计模式”，表明该按钮处于设计模式下。如果该按钮未出现，可能需要单击设计器顶部的信息栏，以重新加载视图。

<Window x:Class="DemoApplication.MainWindow"
    xmlns="https://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="https://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:cc="clr-namespace:CustomControlLibrary;assembly=CustomControlLibrary"
    Title="Window1" Height="300" Width="300">
    <Grid>
        <cc:ButtonWithDesignTime Margin="30,30,30,30" Background="#FFD4D0C8"></cc:ButtonWithDesignTime>
    </Grid>
</Window>

在“设计”视图中，单击 ButtonWithDesignTime 控件将其选中。
右击 ButtonWithDesignTime 控件，指向**“设置背景”，然后选择“蓝色”**。

该控件的背景即设置为蓝色。在 XAML 视图中，将 Background 属性设置为菜单操作指定的值。
运行 DemoApplication 项目。

运行时，该按钮将具有您用快捷菜单设置的背景。

后续步骤

您可以向自定义控件中添加更多设计时功能。

向控件的设计时添加自定义装饰器。有关更多信息，请参见演练：创建设计时装饰器。
为自定义类型创建编辑器，可在“属性”窗口中使用该编辑器。有关更多信息，请参见如何：创建值编辑器。

请参见

参考

PrimarySelectionContextMenuProvider

其他资源

高级扩展性概念

WPF 设计器扩展性

WPF Designer Extensibility Samples