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