Classe UsesItemPolicyAttribute

Articolo
09/12/2008

Aggiornamento: novembre 2007

Limita un provider di funzionalità a un criterio specificato.

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

Sintassi

<AttributeUsageAttribute(AttributeTargets.Class, AllowMultiple := True)> _
Public NotInheritable Class UsesItemPolicyAttribute _
    Inherits RequirementAttribute

Dim instance As UsesItemPolicyAttribute

[AttributeUsageAttribute(AttributeTargets.Class, AllowMultiple = true)]
public sealed class UsesItemPolicyAttribute : RequirementAttribute

[AttributeUsageAttribute(AttributeTargets::Class, AllowMultiple = true)]
public ref class UsesItemPolicyAttribute sealed : public RequirementAttribute

public final class UsesItemPolicyAttribute extends RequirementAttribute

Note

Non tutte le estensioni supportano i criteri.

Esempi

Nell'esempio di codice seguente viene illustrato come connettere un criterio sostitutivo personalizzato a un provider di funzionalità utilizzando UsesItemPolicyAttribute. Per l'elenco di codice completo, vedere Procedura: creare un criterio sostitutivo.

' The DockPanelAdornerProvider class implements an adorner
' that you can use to set the Margin property by using a 
' drag operation. The DockPanelPolicy class enables a 
' container policy for offering additional tasks and 
' adorners on the panel's children.
<UsesItemPolicy(GetType(DockPanelPolicy))>  _
Class DockPanelAdornerProvider
    Inherits AdornerProvider

    Public Sub New() 
        ' The adorner is a Rectangle element.
        Dim r As New Rectangle()
        r.Width = 23.0
        r.Height = 23.0
        r.Fill = AdornerColors.GlyphFillBrush

        ' Set the rectangle's placement in the adorner panel.
        Dim placement As New AdornerPlacementCollection()
        placement.PositionRelativeToAdornerWidth(-1, 0)
        placement.SizeRelativeToAdornerDesiredHeight(1.0, 0)
        placement.SizeRelativeToAdornerDesiredWidth(1.0, 0)
        placement.PositionRelativeToAdornerHeight(-1.0, 0)
        AdornerPanel.SetPlacements(r, placement)

        Dim p As New AdornerPanel()
        p.Children.Add(r)

        AdornerPanel.SetTask(r, New DockPanelMarginTask())

        Adorners.Add(p)
    End Sub
End Class

// The DockPanelAdornerProvider class implements an adorner
// that you can use to set the Margin property by using a 
// drag operation. The DockPanelPolicy class enables a 
// container policy for offering additional tasks and 
// adorners on the panel's children.
[UsesItemPolicy(typeof(DockPanelPolicy))]
class DockPanelAdornerProvider : AdornerProvider
{
    public DockPanelAdornerProvider() 
    {
        // The adorner is a Rectangle element.
        Rectangle r = new Rectangle();
        r.Width = 23.0;
        r.Height = 23.0;
        r.Fill = AdornerColors.GlyphFillBrush;

        // Set the rectangle's placement in the adorner panel.
        AdornerPlacementCollection placement = new AdornerPlacementCollection();
        placement.PositionRelativeToAdornerWidth(-1, 0);
        placement.SizeRelativeToAdornerDesiredHeight(1.0, 0);
        placement.SizeRelativeToAdornerDesiredWidth(1.0, 0);
        placement.PositionRelativeToAdornerHeight(-1.0, 0);
        AdornerPanel.SetPlacements(r, placement);

        AdornerPanel p = new AdornerPanel();
        p.Children.Add(r);

        AdornerPanel.SetTask(r, new DockPanelMarginTask());

        Adorners.Add(p);
    }
}