WPF绑定源

Question

我已经搜索了一个星期以找到答案，但我不能。

由于某些原因，我必须实施Windows.Data.Binding我的自我。所以我创建了一个类，并在其中放置一个私有的Binding对象：

Public Class Binding
Inherits MarkupExtension
Private _Binding As New Windows.Data.Binding

#Region "Properties"

Public Property ElementName() As String
    Get
        Return _Binding.ElementName
    End Get
    Set(value As String)
        _Binding.ElementName = value
    End Set
End Property

Public Property Mode() As BindingMode
    Get
        Return _Binding.Mode
    End Get
    Set(value As BindingMode)
        _Binding.Mode = value
    End Set
End Property

Public Property Source() As Object
    Get
        Return _Binding.Source
    End Get
    Set(value As Object)
        _Binding.Source = value
    End Set
End Property
#End Region
'*Other Properties of Windows.Data.Binding go inside region*

Public Overrides Function ProvideValue(serviceProvider As IServiceProvider) As Object
    If serviceProvider Is Nothing Then
        Return "Design Time"
    Else
        Dim k = _Binding.ProvideValue(serviceProvider)
        Return k
    End If
End Function
End Class

有效。 我需要更改ProvideValue中的一些实现，为此，我需要找到绑定的来源。例如，我在XAML中有一个像这样的对象：

<TextBlock Text={local:Binding Path=UserID} />

好的，我的TextBlock绑定到{{1>} 什么...... ??

问题是绑定的来源是什么？和如何在UserID方法中访问？

感谢所有

Answer 1

这是一个如何使用服务提供商来获取目标的示例。绑定来源

Public Overrides Function ProvideValue(serviceProvider As IServiceProvider) As Object
    Dim service As IProvideValueTarget = DirectCast(serviceProvider.GetService(GetType(IProvideValueTarget)), IProvideValueTarget)
    Dim targetObject As DependencyObject = TryCast(service.TargetObject, DependencyObject)
    Dim targetProperty As DependencyProperty = TryCast(service.TargetProperty, DependencyProperty)

    'find source of the binding'
    Dim targetElement As FrameworkElement = TryCast(targetObject, FrameworkElement)
    If targetElement IsNot Nothing Then
        Dim sourceObject As Object = targetElement.DataContext

        'your logic here'
    End If
End Function

我建议只有在使用转换器和格式时无法实现相同的扩展时才创建自​​己的绑定扩展，并且如果有特定需要这样做的话。

请阅读此处以获取有关IServiceProvider http://msdn.microsoft.com/en-us/library/ee621338.aspx

的更多信息