www.pudn.com > vbTAPI.zip > TAPIvb.bas

Attribute VB_Name = "mTAPIvb" 
'**************************************************************** 
'*  VB file:   TAPIvb.bas... 
'*             VB Callback Proc for TAPI 
'* 
'*  created:        1999 by Ray Mercer 
'* 
'*  last modified:  8/25/99 by Ray Mercer (added comments) 
'* 
'*  NOTE*  This callback proc REQUIRES that you pass an OBJPTR to 
'*  the currect instance of the CvbTAPILine class when calling lineOpen() 
'*  This is one method of simulating how C++ programmers can pass a Me pointer 
'*  in the dwCallbackInstance.  However, in Visual Basic callbacks are volatile 
'*  and if you try stepping through this callback you will probably crash your OS. 
'* 
'*  Copyright (c) 1998 Ray Mercer.  All rights reserved. 
'*  Latest version at http://i.am/shrinkwrapvb 
'**************************************************************** 
Option Explicit 
Private Declare Sub CopyMemory Lib "kernel32.dll" Alias "RtlMoveMemory" _ 
                                    (dest As Any, src As Any, ByVal length As Long) 
 
Public Sub LineCallbackProc(ByVal hDevice As Long, _ 
                                ByVal dwMsg As Long, _ 
                                ByVal dwCallbackInstance As Long, _ 
                                ByVal dwParam1 As Long, _ 
                                ByVal dwParam2 As Long, _ 
                                ByVal dwParam3 As Long) 
    'the callbackInstance parameter contains a pointer to the CvbTAPILine class 
    'this sub just routes all callbacks back to the class for handling there 
    Dim PassedObj As CvbTAPILine 
    Dim objTemp As CvbTAPILine 
    Debug.Print "LineCALLBACK : dwCallbackInst = " & dwCallbackInstance 
    If dwCallbackInstance <> 0 Then 
        'turn pointer into illegal, uncounted reference 
        'Debug.Print "step #1" 
        CopyMemory objTemp, dwCallbackInstance, 4 
        'Assign to legal reference 
        'Debug.Print "step #2" 
        Set PassedObj = objTemp 
        'Destroy the illegal reference 
        'Debug.Print "step #3" 
        CopyMemory objTemp, 0&, 4 
        'use the interface to call back to the class 
        'Debug.Print "step #4" 
        PassedObj.LineProcHandler hDevice, dwMsg, dwParam1, dwParam2, dwParam3 
        'Debug.Print "step #5" 
 
 
    End If 
 
End Sub