Option Explicit Private Const GWL_WNDPROC = -4 Public Const GWL_USERDATA = (-21) Public Const WM_SIZE = &H5 Public Const WM_USER = &H400 Private Declare Function CallWindowProc Lib "user32" Alias _ "CallWindowProcA" (ByVal lpPrevWndFunc As Long, _ ByVal hwnd As Long, ByVal Msg As Long, _ ByVal wParam As Long, ByVal lParam As Long) As Long
Public Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" _ (ByVal hwnd As Long, ByVal nIndex As Long) As Long Private Declare Function SetWindowLong Lib "user32" Alias _ "SetWindowLongA" (ByVal hwnd As Long, _ ByVal nIndex As Long, ByVal dwNewLong As Long) As Long Public Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long Public Function Hook(ByVal hwnd As Long) As Long Dim pOld As Long ‘指定自定义的窗口过程 pOld = SetWindowLong(hwnd, GWL_WNDPROC, _ AddressOf WindowProc) ‘保存原来默认的窗口过程指针 SetWindowLong hwnd, GWL_USERDATA, pOld Hook = pOld End Function
Public Sub Unhook(ByVal hwnd As Long, ByVal lpWndProc As Long) Dim temp As Long 注释：Cease subclassing. temp = SetWindowLong(hwnd, GWL_WNDPROC, lpWndProc) End Sub
Function WindowProc(ByVal hw As Long, ByVal uMsg As Long, _ ByVal wParam As Long, ByVal lParam As Long) As Long If uMsg = WM_SIZE Then ‘处理WM_SIZE消息 MsgBox "SIZE" End If If uMsg = WM_USER + 1 Then MsgBox wParam End If Dim lpPrevWndProc As Long ‘查询原来默认的窗口过程指针 lpPrevWndProc = GetWindowLong(hw, GWL_USERDATA) ‘调用原来的窗口过程 WindowProc = CallWindowProc(lpPrevWndProc, hw, uMsg,wParam, lParam) End Function
在Form中加入以下代码：
Dim wParam As Long Dim lParam As Long Dim lResult As Long Private Sub Command1_Click() wParam = 12345 lResult = SendMessage(Me.hwnd, WM_USER + 1, wParam, lParam) End Sub
Private Sub Form_Load() Me.Tag = Hook(Me.hwnd) End Sub Private Sub Form_Unload(Cancel As Integer) Unhook Me.hwnd, Me.Tag End Sub
在VB中用自定义过程捕获并处理消息的详细信息和例子请参考：
Q170570 HOWTO: Build a Windows Message Handler with AddressOf in Visual http://support.microsoft.com/support/kb/articles/q170/5/70.asp
Q168795 HOWTO: Hook Into a Window注释：s Messages Using AddressOf
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