Classe SelectionPolicy

Articolo
09/12/2008

Aggiornamento: novembre 2007

Criterio che rende disponibili tutti gli elementi nella selezione.

Spazio dei nomi: Microsoft.Windows.Design.Policies
Assembly: Microsoft.Windows.Design.Extensibility (in Microsoft.Windows.Design.Extensibility.dll)

Sintassi

<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

Note

Derivare da questo criterio ed eseguire l'override dei metodi IsInPolicy e GetPolicyItems per filtrare la selezione, se necessario.

Esempi

Nell'esempio di codice seguente viene illustrato come implementare un criterio sostitutivo personalizzato per la selezione primaria. Per l'elenco di codice completo, vedere Procedura: creare un criterio sostitutivo.

' 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;
        }
    }
}