谁能给我一个如何实现 AttachedCommands 的例子？
C# 中有一些示例，我认为它与 C# 非常相似，但我在将代码转换为 VB.NET 时遇到了问题。
目前我尝试将 C# AttachedCommand-Class 转换为 VB.net 看起来像这样：
Imports System
Imports System.Collections.Generic
Imports System.Linq
Imports System.Text
Imports System.Windows
Imports System.Windows.Input
Imports System.Reflection
Public Class AttachedCommand
Inherits DependencyObject
#Region "CommandParameter-Class"
Private NotInheritable Class CommandParameter
Public Shared ReadOnly Property DefaultCP() As CommandParameter
Get
Return New CommandParameter()
End Get
End Property
Private _command As ICommand
Public Property Command() As ICommand
Get
Return _command
End Get
Set(ByVal value As ICommand)
_command = value
End Set
End Property
Private _eventName As String
Public Property EventName() As String
Get
Return _eventName
End Get
Set(ByVal value As String)
_eventName = value
End Set
End Property
Private _callBack As [Delegate]
Public Property Callback() As [Delegate]
Get
Return _callBack
End Get
Set(ByVal value As [Delegate])
_callBack = value
End Set
End Property
End Class
#End Region
#Region "Properties"
Private Shared _parameter As IDictionary(Of DependencyObject, CommandParameter)
Private Shared Property Parameter() As IDictionary(Of DependencyObject, CommandParameter)
Get
Return _parameter
End Get
Set(ByVal value As IDictionary(Of DependencyObject, CommandParameter))
_parameter = value
End Set
End Property
Public Property Command() As ICommand
Get
Return GetValue(CommandProperty)
End Get
Set(ByVal value As ICommand)
SetValue(CommandProperty, value)
End Set
End Property
Public Shared ReadOnly CommandProperty As DependencyProperty = _
DependencyProperty.Register("Command", _
GetType(ICommand), GetType(AttachedCommand), _
New UIPropertyMetadata(AddressOf CommandChanged))
Public Property EventName() As String
Get
Return GetValue(EventNameProperty)
End Get
Set(ByVal value As String)
SetValue(EventNameProperty, value)
End Set
End Property
Public Shared ReadOnly EventNameProperty As DependencyProperty = _
DependencyProperty.Register("EventName", _
GetType(String), GetType(AttachedCommand), _
New UIPropertyMetadata(AddressOf EventNameChanged))
#End Region
#Region "Event-Handler"
Public Shared Sub CommandChanged(ByVal dependencyObject As DependencyObject, ByVal args As DependencyPropertyChangedEventArgs)
If Not Parameter.ContainsKey(dependencyObject) Then
Parameter.Add(dependencyObject, CommandParameter.DefaultCP)
End If
If (Not Parameter(dependencyObject).Callback = Nothing) AndAlso (Not args.OldValue = Nothing) Then
_RemoveEventHandler(dependencyObject)
End If
Parameter(dependencyObject).Command = CType(args.NewValue, ICommand)
_AttachEventHandler(dependencyObject)
End Sub
Public Shared Sub EventNameChanged(ByVal dependencyObject As DependencyObject, ByVal args As DependencyPropertyChangedEventArgs)
If Not Parameter.ContainsKey(dependencyObject) Then
Parameter.Add(dependencyObject, CommandParameter.DefaultCP)
End If
End Sub
#End Region
#Region "Helper"
Private Shared Sub _RemoveEventHandler(ByVal dependencyObject As DependencyObject)
If dependencyObject Is Nothing Then
Throw New ArgumentNullException("DependencyObject is null.")
End If
If Not Parameter.ContainsKey(dependencyObject) Then
Exit Sub
End If
Dim param As CommandParameter = Parameter(dependencyObject)
If param.Callback Is Nothing Then
Throw New InvalidProgramException("Cannot remove Callback. Callback is null.")
End If
Dim eventInfo As EventInfo = dependencyObject.GetType().GetEvent(param.EventName)
If eventInfo Is Nothing Then
Throw New InvalidProgramException(String.Format("Cannot find an event with the name <{0}>", param.EventName))
End If
eventInfo.RemoveEventHandler(dependencyObject, param.Callback)
End Sub
Private Shared Sub _AttachEventHandler(ByVal dependencyObject)
If dependencyObject Is Nothing Then
Throw New ArgumentNullException("DependencyObject is null")
End If
If Not Parameter.ContainsKey(dependencyObject) Then
Exit Sub
End If
Dim param As CommandParameter = Parameter(dependencyObject)
If param.Command Is Nothing Or String.IsNullOrEmpty(param.EventName) Then
Exit Sub
End If
Dim eventInfo As EventInfo = dependencyObject.GetType.GetEvent(param.EventName)
If eventInfo Is Nothing Then
Throw New InvalidProgramException(String.Format("Cannot find an event with the name <{0}>", param.EventName))
End If
eventInfo.AddEventHandler(dependencyObject, param.Callback)
End Sub
Private Shared Sub _CommandExecutAction(ByVal parameter As CommandParameter)
parameter.Command.Execute(Nothing)
End Sub
Private Shared Function _CreateHandler(ByVal eventInfo As EventInfo, ByVal method As Action) As [Delegate]
If eventInfo Is Nothing Then
Throw New ArgumentNullException("EventInfo is null")
End If
If method Is Nothing Then
Throw New ArgumentNullException("Action-method is null")
End If
Dim handlerType = eventInfo.EventHandlerType
Dim eventParams = handlerType.GetMethod("Invoke").GetParameters()
Dim parameters = eventParams.[Select](Function(p) System.Linq.Expressions.Expression.Parameter(p.ParameterType, "x"))
Dim body = System.Linq.Expressions.Expression.[Call](System.Linq.Expressions.Expression.Constant(method), method.[GetType]().GetMethod("Invoke"))
Dim lambda = System.Linq.Expressions.Expression.Lambda(body, parameters.ToArray())
Return [Delegate].CreateDelegate(handlerType, lambda.Compile(), "Invoke", False)
End Function
#End Region
#Region "INIT"
Public Sub New()
Parameter = New Dictionary(Of DependencyObject, CommandParameter)()
End Sub
#End Region
End Class
但现在我遇到了问题，GetValue() 和 SetValue() 方法不可用。有任何想法吗？
感谢您的帮助..