SelectionPolicy 类

项目
09/04/2008

更新：2007 年 11 月

一个使选定内容中的所有项都可用的策略。

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

语法

声明
<RequiresContextItemAttribute(GetType(Selection))> _
<RequiresContextItemAttribute(GetType(Tool))> _
Public Class SelectionPolicy _
    Inherits ItemPolicy
用法
Dim instance As SelectionPolicy

[RequiresContextItemAttribute(typeof(Selection))]
[RequiresContextItemAttribute(typeof(Tool))]
public class SelectionPolicy : ItemPolicy

[RequiresContextItemAttribute(typeof(Selection))]
[RequiresContextItemAttribute(typeof(Tool))]
public ref class SelectionPolicy : public ItemPolicy

public class SelectionPolicy extends ItemPolicy

备注

可从此策略派生并重写 IsInPolicy 和 GetPolicyItems 方法，以便根据需要筛选选定内容。

示例

下面的代码示例演示如何为主选项内容实现自定义代理项策略。有关完整的代码清单，请参见如何：创建代理项策略。

' The DockPanelPolicy class implements a surrogate policy that
' provides container semantics for a selected item. By using 
' this policy, the DemoDockPanel container control offers 
' additional tasks and adorners on its children. 
Class DockPanelPolicy
    Inherits PrimarySelectionPolicy

    Public Overrides ReadOnly Property IsSurrogate() As Boolean 
        Get
            Return True
        End Get
    End Property

    Public Overrides Function GetSurrogateItems( _
        ByVal item As Microsoft.Windows.Design.Model.ModelItem) _
        As System.Collections.Generic.IEnumerable( _
        Of Microsoft.Windows.Design.Model.ModelItem)

        Dim parent As ModelItem = item.Parent

        Dim e As New System.Collections.Generic.List(Of ModelItem)

        If (parent IsNot Nothing) Then

            e.Add(parent)

        End If

        Return e

    End Function

End Class

// The DockPanelPolicy class implements a surrogate policy that
// provides container semantics for a selected item. By using 
// this policy, the DemoDockPanel container control offers 
// additional tasks and adorners on its children. 
class DockPanelPolicy : PrimarySelectionPolicy 
{
    public override bool IsSurrogate 
    {
        get 
        { 
            return true;
        }
    }

    public override IEnumerable<ModelItem> GetSurrogateItems(ModelItem item) 
    {
        ModelItem parent = item.Parent;

        if (parent != null)
        {
            yield return parent;
        }
    }
}