Classe ContextMenuProvider

Artigo
08/25/2010

Define um conjunto de menu itens que são mostrados em um menu de contexto.

Namespace: Microsoft.Windows.Design.Interaction
Assembly: Microsoft.Windows.Design.Extensibility (em Microsoft.Windows.Design.Extensibility.dll)

Sintaxe

Public MustInherit Class ContextMenuProvider _
    Inherits FeatureProvider

Dim instance As ContextMenuProvider

public abstract class ContextMenuProvider : FeatureProvider

public ref class ContextMenuProvider abstract : public FeatureProvider

public abstract class ContextMenuProvider extends FeatureProvider

Comentários

Herdar o ContextMenuProvider classe quando você deseja adicionar um item de menu de contexto a um menu de contexto específico. Aplicando diretivas, sistema autônomo a PrimarySelectionPolicy e o SelectionParentPolicy, você pode controlar quando o provedor do menu de contexto é criado.

A existência de ContextMenuProvider é temporário. Não assuma que ele será persistente por longos períodos de time.

Exemplos

O exemplo de código a seguir mostra como para derivar um tipo personalizado a partir de PrimarySelectionContextMenuProvider classe. O tipo derivado implementa um menu de contexto personalizado, que define o Background propriedade de um controle em time de design. Para obter mais informações, consulte Demonstra Passo a passo: Criando um MenuAction.

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(Control.BackgroundProperty)

        ' 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(Control.BackgroundProperty).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(Control.BackgroundProperty).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 SliderAdornerLib
{
    // 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[Control.BackgroundProperty];

            // 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[Control.BackgroundProperty].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[Control.BackgroundProperty].SetValue(Brushes.Blue);
        }
    }
}

Hierarquia de herança

System.Object
  Microsoft.Windows.Design.Features.FeatureProvider
    Microsoft.Windows.Design.Interaction.ContextMenuProvider
      Microsoft.Windows.Design.Interaction.PrimarySelectionContextMenuProvider

Acesso thread-safe

Quaisquer membros static (Shared no Visual Basic) públicos deste tipo são thread-safe. Não há garantia de que qualquer membro de instância seja thread-safe.