[VB.NET] Passaggio puntatore di una funzione ad una dll

[MItaly]

1. Nel convertire i progetti da VB6 a VB.NET occhio ai tipi numerici, che non corrispondono; usa questa tabella di conversione:

Byte (Bit)   VB6          VB.NET
1 (8)        Byte         Byte (System.Byte)
2 (16)       Integer      Short (System.Int16)
4 (32)       Long         Integer (System.Int32)
8 (64)       n.d.         Long (System.Int64)

2. Fai così:

Public Delegate GUI_STATE_CALLBACK (ByVal GuiStateCallbackCtx As Integer, _
                          ByVal GuiState As Integer, ByVal Response As Byte, _
                          ByVal Message As Integer, ByVal Progress As Byte, _
                          ByVal SampleBuffer As Integer)

Public Declare Function GUICallbacks Lib "PvFw.dll" ( _
    ByVal ModuleHandle As System.IntPtr, ByVal GuiStreamingCallback As System.IntPtr _
    ByVal GuiStreamingCallbackCtx As Integer, ByVal GuiStateCallback As GUI_STATE_CALLBACK _
    ByRef GuiStateCallbackCtx As Integer) As Integer

'...

    Dim ret As Integer
    ret = GUICallbacks(myHandle, 0, IntPtr.Zero, AddressOf TuaProcedura, 0)

'...

Public Function TuaProcedura (ByVal GuiStateCallbackCtx As Integer, _
                          ByVal GuiState As Integer, ByVal Response As Byte, _
                          ByVal Message As Integer, ByVal Progress As Byte, _
                          ByVal SampleBuffer As Integer)
    '...
End Function

Probabilmente anche GuiStreamingCallback è un puntatore a funzione; se intendi utilizzarlo devi creare un delegate anche per lui.