让VB应用程序支持鼠标滚轮(2)

---- 3.TextBox的DataSource均为datPrimaryRS,DataFiled如图所示。

---- 4.窗口下部的网格是DataGrid控件,名称为grdDataGrid。

---- 5.表单From1.frm的清单如下：

Private Sub Form_Load()
Set grdDataGrid.DataSource = _
datPrimaryRS.Recordset("ChildCMD").UnderlyingValue
Hook Me.hWnd
End Sub

Private Sub Form_Unload(Cancel As Integer)
    UnHook Me.hWnd
End Sub

---- 6.标准模块Module1.bas清单如下：
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 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)
    If WHEEL_SCROLL_LINES > Form1.grdDataGrid.VisibleRows Then
WHEEL_SCROLL_LINES = Form1.grdDataGrid.VisibleRows
    End If
End Sub

Public Sub UnHook(ByVal hWnd As Long)
Dim lngReturnValue As Long
lngReturnValue = SetWindowLong(hWnd,
GWL_WNDPROC, lpPrevWndProc)
End Sub

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
            Dim wzDelta, wKeys As Integer
            wzDelta = HIWORD(wParam)
            wKeys = LOWORD(wParam)
            pt.x = LOWORD(lParam)
            pt.y = HIWORD(lParam)
            '将屏幕坐标转换为Form1.窗口坐标
            ScreenToClient Form1.hWnd, pt
            With Form1.grdDataGrid