Public Class MIDI_Handler
    Declare Function midiInOpen Lib "winmm.dll" (ByRef lphMidiIn As Integer, _
      ByVal devIDIn As Integer, _
                                                 ByVal cbfuncIn As test, ByVal _
                                                 cbdataIn As Integer, _
                                                 ByVal cboptionsIn As Integer) _
                                                 As Integer
 
    Public Const CALLBACK_FUNCTION = &H30000
 
    Public Const MM_MIM_OPEN = &H3C1
    Public Const MM_MIM_CLOSE = &H3C2
    Public Const MM_MIM_DATA = &H3C3
    Private Const MIDI_IO_STATUS = &H20&
    Public MidiLocation
 
    Public Delegate Function test(ByVal hmidiIn As Integer, ByVal wMsg As _
      Integer, _
                                  ByVal dwInstance As Integer, ByVal dwParam1 _
                                  As Integer, _
                                  ByVal dwParam2 As Integer) As Boolean
 
    Public Function MidiInProc(ByVal hmidiIn As Integer, ByVal wMsg As Integer, _
      ByVal dwInstance As Integer, _
                               ByVal dwParam1 As Integer, ByVal dwParam2 As _
                               Integer) As Boolean
        MessageBox.Show("Midi-Test")
    End Function
 
    Public Sub OpenMIDI()
        Dim rcin As Integer
        rcin = midiInOpen(MidiLocation, 0, AddressOf MidiInProc, 0, _
          CALLBACK_FUNCTION)
    End Sub
End Class