VB6/VBA中跟踪鼠标移出窗体控件事件(类模块成员函数指针CHooker类应用)

一、关于起因

前几天发了一篇博文，是关于获取VB类模块成员函数指针的内容(http://www.cnblogs.com/alexywt/p/5880993.html)；今天我就发一下我的应用实例。

VB中默认是没有鼠标移出事件响应的，而这个事件其实在项目开发中，实用性很强，很多时候需要在鼠标移出窗体或控件时做些事情；没有这个事件会感觉很费力；

今天我所说的实际案例就是，在窗体上，设计一个SplitterBar控件，窗体的最终用户使用这个控件可以在运行程序时任意调整其内部控件大小。

二、修改CHooker类

我在第二篇参考博文作者开发的CHooker类上做了部分修改(对应以下代码中的中文注释部分代码)，使该类能够跟踪鼠标移开事件，代码如下：

 Option Explicit

 Private Type TRACKMOUSEEVENTTYPE
     cbSize As Long
     dwFlags As Long
     hwndTrack As Long
     dwHoverTime As Long
 End Type

 Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (Destination As Any, Source As Any, ByVal Length As Long)
 Private Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" (ByVal hWnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
 Private Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" (ByVal hWnd As Long, ByVal nIndex As Long) As Long
 Private Declare Function IsWindow Lib "user32" (ByVal hWnd As Long) As Long
 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
 Private Declare Function TrackMouseEvent Lib "user32" (lpEventTrack As TRACKMOUSEEVENTTYPE) As Long

 Private Const GWL_WNDPROC = (-)
 Private Const WM_NCDESTROY = &H82
 Private Const WM_MOUSEMOVE = &H200
 Private Const TME_LEAVE = &H2&
 Private Const WM_MOUSELEAVE = &H2A3&

 Public Event WindowProc(ByVal Msg As Long, ByVal wParam As Long, ByVal lParam As Long, bCallNext As Boolean, lReturn As Long)

 Private m_hwnd As Long, m_NewProc As Long, m_OldProc As Long
 Private m_TrackMouseLeave As Boolean        'm_TrackMouseLeave设置在Hook时是否开启跟踪鼠标移开事件，是否正在跟踪移动事件
 Private m_Tracking As Boolean               '跟踪移开事件时，标识当前是否正在跟踪移动事件

 Private Sub Class_Initialize()
     m_NewProc = GetClassProcAddr(Me, , , True)
 End Sub

 Private Sub Class_Terminate()
     Call Unbind
 End Sub

 Public Function Bind(ByVal hWnd As Long, Optional TrackMouseLeave As Boolean = False) As Boolean
     Call Unbind
     If IsWindow(hWnd) Then m_hwnd = hWnd
     m_OldProc = SetWindowLong(m_hwnd, GWL_WNDPROC, m_NewProc)
     Bind = CBool(m_OldProc)
     m_TrackMouseLeave = TrackMouseLeave '保存用户传递的跟踪鼠标移开事件设置
 End Function

 Public Function Unbind() As Boolean
     If m_OldProc <>  Then Unbind = CBool(SetWindowLong(m_hwnd, GWL_WNDPROC, m_OldProc))
     m_OldProc =
 End Function

 Private Function WindowProcCallBack(ByVal hWnd As Long, ByVal Msg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
     Dim bCallNext As Boolean, lReturn As Long
     Dim tTrackML As TRACKMOUSEEVENTTYPE '一个移开事件结构声明

     bCallNext = True

     RaiseEvent WindowProc(Msg, wParam, lParam, bCallNext, lReturn)
     '当用户需要跟踪鼠标移开事件时
     If m_TrackMouseLeave Then
         '鼠标在其上移动，当前未标识为跟踪状态(第一次或者移开鼠标后重新移动回来时)
         If Msg = WM_MOUSEMOVE And m_Tracking = False Then
             m_Tracking = True
             'initialize structure
             tTrackML.cbSize = Len(tTrackML)
             tTrackML.hwndTrack = hWnd
             tTrackML.dwFlags = TME_LEAVE
             'start the tracking
             TrackMouseEvent tTrackML
         End If
         '鼠标移开时，取消跟踪状态
         If Msg = WM_MOUSELEAVE Then m_Tracking = False
     End If

     If bCallNext Then
         WindowProcCallBack = CallWindowProc(m_OldProc, hWnd, Msg, wParam, lParam)
     Else
         WindowProcCallBack = lReturn
     End If
     If hWnd = m_hwnd And Msg = WM_NCDESTROY Then Call Unbind
 End Function

 Private Function GetClassProcAddr(obj As Object, ByVal Index As Long, _
    Optional ByVal ParamCount As Long = , Optional ByVal HasReturnValue As Boolean) As Long
     Static lReturn As Long, pReturn As Long
     Static AsmCode() As Byte

     Dim i As Long, pThis As Long, pVtbl As Long, pFunc As Long

     pThis = ObjPtr(obj)
     CopyMemory pVtbl, ByVal pThis,
     CopyMemory pFunc, ByVal pVtbl + ( + Index) * ,
     pReturn = VarPtr(lReturn)
     For i =  To UBound(AsmCode)                                '填充nop
         AsmCode(i) = &H90
     Next
     AsmCode() = &H55                                           'push   ebp
     AsmCode() = &H8B: AsmCode() = &HEC                        'mov    ebp,esp
     AsmCode() = &H53                                           'push   ebx
     AsmCode() = &H56                                           'push   esi
     AsmCode() = &H57                                           'push   edi
     If HasReturnValue Then
         AsmCode() = &HB8                                       'mov    offset lReturn
         CopyMemory AsmCode(), pReturn,
         AsmCode() = &H50                                      'push   eax
     End If
     For i =  To ParamCount -                                  'push   dword ptr[ebp+xx]
         AsmCode( + i * ) = &HFF
         AsmCode( + i * ) = &H75
         AsmCode( + i * ) = (ParamCount - i) *  +
     Next
     i = i *  +
     AsmCode(i) = &HB9                                           'mov    ecx,this
     CopyMemory AsmCode(i + ), pThis,
     AsmCode(i + ) = &H51                                       'push ecx
     AsmCode(i + ) = &HE8                                       'call 相对地址
     CopyMemory AsmCode(i + ), pFunc - VarPtr(AsmCode(i + )) - ,
     If HasReturnValue Then
         AsmCode(i + ) = &HB8                                  'mov    eax,offset lReturn
         CopyMemory AsmCode(i + ), pReturn,
         AsmCode(i + ) = &H8B                                  'mov    eax,dword ptr[eax]
         AsmCode(i + ) = &H0
     End If
     AsmCode(i + ) = &H5F                                      'pop    edi
     AsmCode(i + ) = &H5E                                      'pop    esi
     AsmCode(i + ) = &H5B                                      'pop    ebx
     AsmCode(i + ) = &H8B: AsmCode(i + ) = &HE5              'mov    esp,ebp
     AsmCode(i + ) = &H5D                                      'pop    ebp
     AsmCode(i + ) = &HC3                                      'ret
     GetClassProcAddr = VarPtr(AsmCode())
 End Function

三、CHooker类的使用

那么如何使用这个新构建的类，来实现我们的需求了？首先创建一个窗体，放置三个PictureBox，其中一个做为SplitterBar(name属性picture4)，其余2个图片框的宽度将会由SplitterBar在运行时调整。

 Private Type POINTAPI
     x As Long
     y As Long
 End Type

 Private Declare Function GetCursorPos Lib "user32" (lpPoint As POINTAPI) As Long

 Private mCanMove      As Boolean
 Private mPreCursorPos As POINTAPI
 Private mCurCursorPos As POINTAPI
 Private WithEvents mHooker As CHooker

 Private Sub MDIForm_Load()
     Set mHooker = New CHooker
     call mHooker.Bind(Picture4.hWnd, True)
 End Sub

 Private Sub MDIForm_Unload(Cancel As Integer)
     mHooker.Unbind
     Set mHooker = Nothing
 End Sub

 Private Sub mHooker_WindowProc(ByVal Msg As Long, ByVal wParam As Long, ByVal lParam As Long, bCallNext As Boolean, lReturn As Long)
     If Msg = WM_MOUSELEAVE Then Me.MousePointer =
 End Sub

 Private Sub picture4_MouseDown(Button As Integer, Shift As Integer, x As Single, y As Single)
     Call GetCursorPos(mPreCursorPos)
 End Sub

 Private Sub picture4_MouseMove(Button As Integer, Shift As Integer, x As Single, y As Single)
     Me.MousePointer = vbSizeWE
     If (Button And vbLeftButton) >  Then
         Call GetCursorPos(mCurCursorPos)
         mCanMove = True
         Picture4.Move Picture4.Left + (mCurCursorPos.x - mPreCursorPos.x) * mdlCommon.TwipsPerPixelX()
         mPreCursorPos = mCurCursorPos
     End If
 End Sub

 Private Sub picture4_MouseUp(Button As Integer, Shift As Integer, x As Single, y As Single)
     If mCanMove Then
         '此处添加调整界面元素位置与大小的代码
     End If
 End Sub

四、其他说明

mdlCommon.TwipsPerPixelX()函数是在模块mdlCommon的一个公共函数，相关代码如下：

 Private Declare Function GetDC Lib "user32" (ByVal hWnd As Long) As Long
 Private Declare Function GetDeviceCaps Lib "gdi32" (ByVal hdc As Long, ByVal nIndex As Long) As Long
 Private Declare Function ReleaseDC Lib "user32" (ByVal hWnd As Long, ByVal hdc As Long) As Long

 Private Const HWND_DESKTOP As Long =
 Private Const LOGPIXELSX   As Long =
 Private Const LOGPIXELSY   As Long = 

 'TwipsPerPixelX：屏幕水平方向上1像素转换为对应的缇值
 Public Function TwipsPerPixelX() As Single
     Dim lngDC As Long

     lngDC = GetDC(HWND_DESKTOP)
     TwipsPerPixelX = & / GetDeviceCaps(lngDC, LOGPIXELSX)
     ReleaseDC HWND_DESKTOP, lngDC
 End Function

 'TwipsPerPixelY：屏幕垂直方向上1像素转换为对应的缇值
 Public Function TwipsPerPixelY() As Single
     Dim lngDC As Long

     lngDC = GetDC(HWND_DESKTOP)
     TwipsPerPixelY = & / GetDeviceCaps(lngDC, LOGPIXELSY)
     ReleaseDC HWND_DESKTOP, lngDC
 End Function