MenuGroup.HasDropDown 属性

项目
08/12/2011

获取或设置一个值，该值表示 Items 中的菜单项是否可以添加下级菜单。

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 HasDropDown As Boolean
    Get
    Set

public bool HasDropDown { get; set; }

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

member HasDropDown : bool with get, set

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

属性值

类型：System.Boolean
如果项集合中的菜单项将被添加到子菜单，则为 true；如果集合中的项将直接被添加到当前菜单，并将在各端用分隔符呈现出来，则为 false。

备注

如果 HasDropDown 等于 true，在项集合中的菜单项将添加到一个子菜单。其 DisplayName 属性设置为 MenuGroup 的菜单项被添加到当前菜单，其他菜单项被添加到子菜单。如果 HasDropDown 等于 false，则集合中的菜单项会直接添加到当前菜单中，且两端都呈现分隔符。例如，考虑菜单组中的 **“布局”**以及菜单项中 “左对齐” 和 “右对齐”。如果 HasDropDown 等于 true，一个布局菜单将添加到当前的菜单中，带有 左对齐 和 右对齐 的子菜单项。如果 HasDropDown 等于 false，左对齐 和 右对齐 将添加到 左对齐 前会显示分隔符的和 右对齐 后会显示分隔符的当前菜单中。

示例

以下代码示例演示如何设置两个 MenuAction 项并将其赋给一个 MenuGroup。 HasDropDown 属性被设置为 true 来启用飞出行为。有关更多信息，请参见演练：创建菜单提供程序。

' 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 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);
}