有人能否解释一下.NET中的环境属性(Ambient Attribute)?
它用于解决像
<Setter Property="P" Value="V" />
这样的问题。在将V转换为正确类型的值之前,您必须了解P(实际上是P的类型)。
您可以使用[Ambient]标记“Property”属性,并且1.加载程序将首先处理“Property”,2.允许“Value”类型转换器在运行时读取“Type”值。
这也是{StaticResource foo}
如何通过XAML父级查找可能在其中具有“foo”的ResourceDictionary。
例如:
// This markup extension returns the number of Ambient "Resource" properties
// Found in the XAML tree above it.
// The FrameworkElement.Resources property is already marked [Ambient]
public class MyMarkupExtension : MarkupExtension
{
public override object ProvideValue(IServiceProvider serviceProvider)
{
var schemaProvider = serviceProvider.GetService(typeof(IXamlSchemaContextProvider)) as IXamlSchemaContextProvider;
var ambientProvider = serviceProvider.GetService(typeof(IAmbientProvider)) as IAmbientProvider;
XamlMember resourcesProperty = new XamlMember(typeof(FrameworkElement).GetProperty("Resources"), schemaProvider.SchemaContext);
List<AmbientPropertyValue> resources = (List<AmbientPropertyValue>) ambientProvider.GetAllAmbientValues(null, resourcesProperty);
Debug.WriteLine("found {0} FramewrkElement.Resources Properties", resources.Count);
return resources.Count.ToString();
}
}