ContextMenuProvider.UpdateItemStatus 事件

项目
09/04/2008

更新：2007 年 11 月

在要显示菜单项时发生。

命名空间： Microsoft.Windows.Design.Interaction
程序集： Microsoft.Windows.Design.Extensibility（在 Microsoft.Windows.Design.Extensibility.dll 中）

语法

声明
Public Event UpdateItemStatus As EventHandler(Of MenuActionEventArgs)
用法
Dim instance As ContextMenuProvider
Dim handler As EventHandler(Of MenuActionEventArgs)

AddHandler instance.UpdateItemStatus, handler

public event EventHandler<MenuActionEventArgs> UpdateItemStatus

public:
 event EventHandler<MenuActionEventArgs^>^ UpdateItemStatus {
    void add (EventHandler<MenuActionEventArgs^>^ value);
    void remove (EventHandler<MenuActionEventArgs^>^ value);
}

JScript 不支持事件。

示例

下面的代码示例演示如何处理 UpdateItemStatus 事件，以便用主选项内容中的值更新 MenuAction 对象。有关更多信息，请参见演练：创建 MenuAction。

' 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 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;
    }
}