VB为自己的程序设定消息(可接收处理)

VB为自己的程序设定消息(可接收处理)
Posted by JiaJia 5 March,2009 (0)Comment
　　用API函数 SetWindowLong 指定处理消息的窗口过程为自定义的函数 WindowProc，捕获消息ID为 WM_USER+1 的自定义消息或系统消息。并且，为了保证窗口能正确的响应消息，需要保存原来默认的窗口过程并在自定义函数WindowProc中调用。如下例，在按钮事件中发送自定义消息，WindowProc 捕获了窗口大小变化的系统定义消息和用户自定义的消息并显示用户自定义的消息参数 wParam。
Form 部分代码
Private Sub Command1_Click()
Dim wParam As Long
Dim lParam As Long
Dim lResult As Long
　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
Mod 部分代码
Option Explicit
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
Private Const GWL_WNDPROC = -4
Public Const GWL_USERDATA = (-21)
Public Const WM_SIZE = &H5
Public Const WM_USER = &H400
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_WNDP