我需要对Mapx控件支持鼠标滚轮，找了一个可以使用的代码，来自
http://blog.csdn.net/areful/archive/2007/10/19/1832010.aspx
需要注意的是，在FormLoad中增加Hook Map1.hWnd，在Form_Unload中增加UnHook Map1.hWnd
另外，在鼠标移动经过Map时，可以激发Map的mousemove事件，但滚轮无效，因为焦点不在Map上，可以用Map1.SetFocus来设置焦点。
模块代码：
代码语言：javascript复制Option Explicit
Public Type POINTL
X As Long
Y As Long
End Type
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
Declare Function SetWindowLong Lib "USER32" Alias "SetWindowLongA" (ByVal hWnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
Declare Function SystemParametersInfo Lib "USER32" Alias "SystemParametersInfoA" (ByVal uAction As Long, ByVal uParam As Long, lpvParam As Any, ByVal fuWinIni As Long) As Long
Declare Function ScreenToClient Lib "USER32" (ByVal hWnd As Long, xyPoint As POINTL) As Long
Public Const GWL_WNDPROC = -4
Public Const SPI_GETWHEELSCROLLLINES = 104
Public Const WM_MOUSEWHEEL = &H20A
Public WHEEL_SCROLL_LINES As Long
Global lpPrevWndProc As Long
Public sngX As Single, sngY As Single '鼠标坐标
Public intShift As Integer '鼠标按键
Public bWay As Boolean '鼠标方向
Public bMouseFlag As Boolean '鼠标事件激活标志
'*************************************************************************
'**函 数 名：Hook
'**输 入：ByVal hWnd(Long) - 窗口句柄
'**输 出：无
'**功能描述：安装鼠标钩子
'*************************************************************************
Public Sub Hook(ByVal hWnd As Long)
lpPrevWndProc = SetWindowLong(hWnd, GWL_WNDPROC, AddressOf WindowProc)
'获取"控制面板"中的滚动行数值
Call SystemParametersInfo(SPI_GETWHEELSCROLLLINES, 0, WHEEL_SCROLL_LINES, 0)
End Sub
'*************************************************************************
'**函 数 名：UnHook
'**输 入：ByVal hWnd(Long) - 窗口句柄
'**输 出：无
'**功能描述：卸载鼠标钩子
'*************************************************************************
Public Sub UnHook(ByVal hWnd As Long)
Dim lngReturnValue As Long
lngReturnValue = SetWindowLong(hWnd, GWL_WNDPROC, lpPrevWndProc)
End Sub
'*************************************************************************
'**函 数 名：WindowProc
'**输 入：ByVal hw(Long) - 窗口句柄
'** ：ByVal uMsg(Long) - 消息类型
'** ：ByVal wParam(Long) -
'** ：ByVal lParam(Long) -
'*************************************************************************
Private Function WindowProc(ByVal hw As Long, ByVal uMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
Dim pt As POINTL
Select Case uMsg
Case WM_MOUSEWHEEL '滚动
Dim wzDelta, wKeys As Integer
'wzDelta传递滚轮滚动的快慢，该值小于零表示滚轮向后滚动（朝用户方向），
'大于零表示滚轮向前滚动（朝显示器方向）
wzDelta = HIWORD(wParam)
'wKeys指出是否有CTRL=8、SHIFT=4、鼠标键(左=2、中=16、右=2、附加)按下，允许复合
wKeys = LOWORD(wParam)
'pt鼠标的坐标
pt.X = LOWORD(lParam)
pt.Y = HIWORD(lParam)
'--------------------------------------------------
If wzDelta < 0 Then '朝用户方向
bWay = True
'在这里你自己处理－－－－－－－－－－－－－－－－－－
main.Cmap.ZoomOut
'MsgBox 0 '这行代码由我加入，使用时改为你自己的代码
Else '朝显示器方向
bWay = False
main.Cmap.ZoomIn
'MsgBox 1 '这行代码由我加入，使用时改为你自己的代码
End If
'--------------------------------------------------
'将屏幕坐标转换为Form1.窗口坐标
ScreenToClient hw, pt
sngX = pt.X
sngY = pt.Y
intShift = wKeys
bMouseFlag = True '置滚动标志
Case Else
WindowProc = CallWindowProc(lpPrevWndProc, hw, uMsg, wParam, lParam)
End Select
End Function
'*************************************************************************
'**函 数 名：HIWORD
'**输 入：LongIn(Long) - 32位值
'**输 出：(Integer) - 32位值的低16位
'**功能描述：取出32位值的高16位
'*************************************************************************
Public Function HIWORD(LongIn As Long) As Integer
' 取出32位值的高16位
HIWORD = (LongIn And &HFFFF0000) &H10000
End Function
'*************************************************************************
'**函 数 名：LOWORD
'**输 入：LongIn(Long) - 32位值
'**输 出：(Integer) - 32位值的低16位
'**功能描述：取出32位值的低16位
'*************************************************************************
Public Function LOWORD(LongIn As Long) As Integer
' 取出32位值的低16位
LOWORD = LongIn And &HFFFF&
End Function
