Appel API en vb.net fonction midi midiOutPrepareHeader problème de parametre en code managé

   Public Class MIDIHDR

   Public lpData As Int32 ' pointer to locked data block

   Public dwBufferLength As Int32 ' length of data in data block

   Public dwBytesRecorded As Int32 ' used for input only

   Public dwUser As Int32 ' for client's use

   Public dwFlags As Int32 ' assorted flags (see defines)

   Public lpNext As Int32 ' struct midihdr_tag FAR *reserved for driver

   Public reserved As Int32 ' reserved for driver

   Public dwOffset As Int32 ' Callback offset into buffer

   Public dwReserved1 As Int32 ' Reserved for MMSYSTEM

   Public dwReserved2 As Int32 ' Reserved for MMSYSTEM

   Public dwReserved3 As Int32 ' Reserved for MMSYSTEM

   Public dwReserved4 As Int32 ' Reserved for MMSYSTEM

   Public dwReserved5 As Int32 ' Reserved for MMSYSTEM

   Public dwReserved6 As Int32 ' Reserved for MMSYSTEM

   Public dwReserved7 As Int32 ' Reserved for MMSYSTEM

   Public dwReserved8 As Int32 ' Reserved for MMSYSTEM

End Class

Private Sub messageSysEx()

Dim c() As Byte = {&HF0, &H41, &H0, &H0, &H1B, &H12, &H7, &H0, _

&H0, &H0, &H1, &H0, &H1C, &H13, &H45, &H32, _

&H1E, &H3, &H32, &H0, &H0, &H46, &H55, &H1E, _

&H0, &H55, &H8, &H32, &H0, &H0, &H32, &H64, _

&H0, &H4B, &H5A, &H46, &H36, &HF7}

Dim err As Integer

Dim LocHeader As New MIDIHDR

Dim taille As Integer = 38

Dim PtrStruct As Long

Dim NumPort As Integer = 2

If midiOutOpen(hMidi, NumPort, 0, 0, CALLBACK_NULL) = 0 Then

Dim gch As GCHandle = GCHandle.Alloc(c, GCHandleType.Pinned)

'---- Affectation adresse du buffer -----

LocHeader.lpData = gch.AddrOfPinnedObject.ToInt32

'----- Affectation du nombre d'octets à envoyer et Flags -----

LocHeader.dwBufferLength = taille

LocHeader.dwFlags = 0

'----- Préparation du buffer -----

Dim gchStruct As GCHandle = GCHandle.Alloc(LocHeader, GCHandleType.Pinned)

PtrStruct = gchStruct.AddrOfPinnedObject.ToInt32

err = midiOutPrepareHeader(hMidi, PtrStruct, Marshal.SizeOf(LocHeader))  'Retourne err = 11 au lieu de 0 (invalid para

'----- Copie en retour des infos dans le header -----

If err = 0 Then

' ----- Envoi du message -----

err = midiOutLongMsg(hMidi, PtrStruct, Marshal.SizeOf(LocHeader))

'----- Attente message envoyé -----

While midiOutUnprepareHeader(hMidi, PtrStruct, Marshal.SizeOf(LocHeader)) = MMSYSERR_STILLPLAYING

System.Threading.Thread.Sleep(20)

End While

End If

gchStruct.Free()

gch.Free()

'----- Fermeture du port -----

err = midiOutClose(hMidi)

End If