我有一些问题要将我的VB6项目转换为VB.NET
我不明白这个“AddressOf”函数应该如何在VB.NET中使用
我的VB6代码:
Declare Function MP4_ClientStart Lib "hikclient.dll" _
(pClientinfo As CLIENT_VIDEOINFO, ByVal abab As Long) As Long
Public Sub ReadDataCallBack(ByVal nPort As Long, pPacketBuffer As Byte, _
ByVal nPacketSize As Long)
If Not bSaved_DVS Then
bSaved_DVS = True
HW_OpenStream hChannelHandle, pPacketBuffer, nPacketSize
End If
HW_InputData hChannelHandle, pPacketBuffer, nPacketSize
End Sub
nn1 = MP4_ClientStart(clientinfo, AddressOf ReadDataCallBack)
您可能会看到此错误:
'AddressOf'表达式无法转换为'Long',因为'Long'不是委托类型。
你可能想要做的是创建一个委托然后将adab的类型更改为该委托类型。将此添加到类中:
Public Delegate Sub ReadDataCallBackDelegate(ByVal nPort As Long, _
ByVal pPacketBuffer As Byte, ByVal nPacketSize As Long)
然后将您的P / Invoke声明更改为:
Declare Function MP4_ClientStart Lib "hikclient.dll" (ByVal pClientinfo As _
CLIENT_VIDEOINFO, ByVal abab As ReadDataCallBackDelegate) As Long
不要删除/更改您的ReadDataCallBack Sub,您仍然需要它。
那时他编译应该很开心。但是,其他人提出的观点很重要。 VB6中的整数和长整数的长度与VB.NET中的长度不同。因此在.NET中,只要在VB6中使用Long,就需要使用Integer。
关于非托管代码中的回调,看看这个类似的post是否对你有帮助。
关于你的问题 - 我认为你不需要回调函数或你发布的示例不正确/完整 - 请参阅上面指出的帖子并澄清你的代码示例。
我假设MP4_ClientStart的第二个参数应该是回调函数的地址。可能问题是你在这里将它定义为Long,在VB6中是32位值,但在VB.NET中是64位值。您可能会通过将声明更改为:
Declare Function MP4_ClientStart Lib "hikclient.dll" _
(pClientinfo As CLIENT_VIDEOINFO, ByVal abab As Integer) As Integer
非常好,谢谢!
我是这样做的
VB.NET代码:
Declare Function MP4_ClientStart Lib "hikclient.dll" (ByRef pClientinfo As _
CLIENT_VIDEOINFO, ByVal abab As ReadDataCallBackDelegate) As Integer
Public Delegate Sub ReadDataCallBackDelegate(ByVal nPort As Long, _
ByRef pPacketBuffer As Byte, ByVal nPacketSize As Long)
Public Sub ReadDataCallBack(ByVal nPort As Integer, ByRef pPacketBuffer As _
Byte, ByVal nPacketSize As Integer)
If Not bSaved_DVS Then
bSaved_DVS = True
HW_OpenStream(hChannelHandle, pPacketBuffer, nPacketSize)
End If
HW_InputData(hChannelHandle, pPacketBuffer, nPacketSize)
End Sub
MP4_ClientStart(clientinfo, AddressOf ReadDataCallBack)