UsesItemPolicyAttribute 类
更新：2007 年 11 月
将功能提供程序限制给指定策略。
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
<AttributeUsageAttribute(AttributeTargets.Class, AllowMultiple := True)> _
Public NotInheritable Class UsesItemPolicyAttribute _
Inherits RequirementAttribute
用法
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
备注
并非所有扩展都支持策略。
示例
下面的代码示例演示如何通过使用 UsesItemPolicyAttribute 将自定义代理项策略附加到功能提供程序。有关完整的代码清单，请参见如何：创建代理项策略。
' 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);
}
}
继承层次结构
System.Object
System.Attribute
Microsoft.Windows.Design.RequirementAttribute
Microsoft.Windows.Design.Policies.UsesItemPolicyAttribute
线程安全
此类型的任何公共 static（在 Visual Basic 中为 Shared） 成员都是线程安全的。但不保证所有实例成员都是线程安全的。
另请参见
参考
Microsoft.Windows.Design.Policies 命名空间