MenuAction.Enabled 属性

项目
05/28/2012

[本文档仅供预览，在以后的发行版中可能会发生更改。包含的空白主题用作占位符。]

获取或设置一个值指示是否用户可以使用菜单操作项。

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

语法

声明
Public Property Enabled As Boolean

public bool Enabled { get; set; }

public:
property bool Enabled {
    bool get ();
    void set (bool value);
}

member Enabled : bool with get, set

function get Enabled () : boolean
function set Enabled (value : boolean)

属性值

类型：System.Boolean
如果用户可以使用该菜单操作项，则为 true；否则为 false。默认值为 true。

备注

当 Enabled 和 Visible 属性为 true 时，设计器对 Command 调用 Execute 方法。

示例

下面的代码示例演示如何根据控件的 Background 属性的值来设置两个 MenuAction 项。有关更多信息，请参见演练：创建菜单提供程序。

' 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 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;
    }
}