在VB的类模块中使用定时器

长久以来，由于不能直接获得VB类成员函数指针，因为无法在VB的类模块中直接使用定时器控件或定时器API，基于俺编写的获得类成员函数指针的函数，俺编写了这个带定时器功能的类，希望给朋友们一些启发。

一、新建一个类，类名称为clsTimer，类代码如下：

Option Explicit '* ******************************************** * '* 模块名称：clsTimer.cls '* 功能：在VB类模块中使用计时器 '* 作者：lyserver '* ******************************************** * Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (Destination As Any,_ Source As Any,ByVal Length As Long) Private Declare Function SetTimer Lib "user32" (ByVal hwnd As Long,ByVal nIDEvent As Long,_ ByVal uElapse As Long,ByVal lpTimerFunc As Long) As Long Private Declare Function KillTimer Lib "user32" (ByVal hwnd As Long,ByVal nIDEvent As Long) As Long Dim m_idTimer As Long Dim m_Enabled As Boolean Dim m_Interval As Long Dim m_lTimerProc As Long Private Sub Class_Initialize() m_Interval = 0 m_lTimerProc = GetClassProcAddr(8) End Sub Private Sub Class_Terminate() If m_idTimer <> 0 Then KillTimer 0,m_idTimer End Sub Public Property Get Interval() As Long Interval = m_Interval End Property Public Property Let Interval(ByVal New_Value As Long) If New_Value >= 0 Then m_Interval = New_Value End Property Public Property Get Enabled() As Boolean Enabled = m_Enabled End Property Public Property Let Enabled(ByVal New_Value As Boolean) m_Enabled = New_Value If m_idTimer <> 0 Then KillTimer 0,m_idTimer If New_Value And m_Interval > 0 Then m_idTimer = SetTimer(0,m_Interval,m_lTimerProc) End If End Property Private Function GetClassProcAddr(ByVal Index As Long,Optional ParamCount As Long = 4,Optional HasReturnValue As Boolean) As Long Static lReturn As Long,pReturn As Long Static AsmCode(50) As Byte Dim i As Long,pThis As Long,pVtbl As Long,pFunc As Long pThis = ObjPtr(Me) CopyMemory pVtbl,ByVal pThis,4 CopyMemory pFunc,ByVal pVtbl + (6 + Index) * 4,4 pReturn = VarPtr(lReturn) For i = 0 To UBound(AsmCode) AsmCode(i) = &H90 Next AsmCode(0) = &H55 AsmCode(1) = &H8B: AsmCode(2) = &HEC AsmCode(3) = &H53 AsmCode(4) = &H56 AsmCode(5) = &H57 If HasReturnValue Then AsmCode(6) = &HB8 CopyMemory AsmCode(7),pReturn,4 AsmCode(11) = &H50 End If For i = 0 To ParamCount - 1 AsmCode(12 + i * 3) = &HFF AsmCode(13 + i * 3) = &H75 AsmCode(14 + i * 3) = (ParamCount - i) * 4 + 4 Next i = i * 3 + 12 AsmCode(i) = &HB9 CopyMemory AsmCode(i + 1),pThis,4 AsmCode(i + 5) = &H51 AsmCode(i + 6) = &HE8 CopyMemory AsmCode(i + 7),pFunc - VarPtr(AsmCode(i + 6)) - 5,4 If HasReturnValue Then AsmCode(i + 11) = &HB8 CopyMemory AsmCode(i + 12),4 AsmCode(i + 16) = &H8B AsmCode(i + 17) = &H0 End If AsmCode(i + 18) = &H5F AsmCode(i + 19) = &H5E AsmCode(i + 20) = &H5B AsmCode(i + 21) = &H8B: AsmCode(i + 22) = &HE5 AsmCode(i + 23) = &H5D AsmCode(i + 24) = &HC3 GetClassProcAddr = VarPtr(AsmCode(0)) End Function Private Sub TimerProc(ByVal hwnd As Long,ByVal uMsg As Long,ByVal idEvent As Long,ByVal dwTime As Long) Debug.Print "类模板中的计时器：",uMsg,idEvent,dwTime End Sub

二、测试代码如下：

Dim m_tm As clsTimer Private Sub Form_Load() Set m_tm = New clsTimer End Sub Private Sub Form_Unload(Cancel As Integer) Set m_tm = Nothing End Sub Private Sub Command1_Click() m_tm.Interval = 1000 m_tm.Enabled = True End Sub Private Sub Command2_Click() m_tm.Enabled = False End Sub

（编辑：李大同）

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