SelectionPolicy 類別

發行項
08/21/2008

更新：2007 年 11 月

原則，會讓選取範圍中的所有項目都可以使用。

命名空間： Microsoft.Windows.Design.Policies
組件： Microsoft.Windows.Design.Extensibility (在 Microsoft.Windows.Design.Extensibility.dll 中)

語法

<RequiresContextItemAttribute(GetType(Selection))> _
<RequiresContextItemAttribute(GetType(Tool))> _
Public Class SelectionPolicy _
    Inherits ItemPolicy

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

備註

您可以衍生自這個原則並覆寫 IsInPolicy 和 GetPolicyItems 方法，視需要篩選選取範圍。

範例

下列程式碼範例示範如何實作主要選取的自訂代理原則。如需完整的程式碼清單，請參閱 HOW TO：建立 Surrogate 原則。

' 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;
        }
    }
}