已经完成了窗体上滚动块的设计,但还需要支持鼠标滚轮才算完整,
下面有两段VB6支持鼠标滚轮的代码,但运行后出错,请高手指点一下问题的所在:
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
制作标准模块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

'判断坐标是否在Form1.grdDataGrid窗口内
If pt.x > .Left / Screen.TwipsPerPixelX And _
pt.x < (.Left + .Width) / Screen.TwipsPerPixelX And _
pt.y > .Top / Screen.TwipsPerPixelY And _
pt.y < (.Top + .Height) / Screen.TwipsPerPixelY Then
'滚动明细数据库
If wKeys = 16 Then
'滚动键按下，水平滚动grdDataGrid
If Sgn(wzDelta) = 1 Then
Form1.grdDataGrid.Scroll -1, 0
Else
Form1.grdDataGrid.Scroll 1, 0
End If
Else
'垂直滚动grdDataGrid
If Sgn(wzDelta) = 1 Then
Form1.grdDataGrid.Scroll 0, 0 - WHEEL_SCROLL_LINES
Else
Form1.grdDataGrid.Scroll 0, WHEEL_SCROLL_LINES
End If
End If
Else
'鼠标不在grdDataGrid区域，滚动主数据库
With Form1.datPrimaryRS.Recordset
If Sgn(wzDelta) = 1 Then
If .BOF = False Then
.MovePrevious
If .BOF = True Then
.MoveFirst
End If
End If
Else
If .EOF = False Then
.MoveNext
If .EOF = True Then
.MoveLast
End If
End If
End If
End With
End If
End With
Case Else
WindowProc = CallWindowProc(lpPrevWndProc, hw, _
uMsg, wParam, lParam)
End Select
End Function

Public Function HIWORD(LongIn As Long) As Integer
' 取出32位值的高16位
HIWORD = (LongIn And &HFFFF0000) \ &H10000
End Function

Public Function LOWORD(LongIn As Long) As Integer
' 取出32位值的低16位
LOWORD = LongIn And &HFFFF&
End Function

将上面第一段加到原form1.frm中:下面第4行先出错
Option Explicit'这是原来form1中有的语句.

Private Sub Form_Load()'这一段是鼠标滚轮加上的
Set grdDataGrid.DataSource = _
datPrimaryRS.Recordset("ChildCMD").UnderlyingValue'先出错在此,说datPrimaryRS变量未定义,不知何意?
Hook Me.hWnd
End Sub

Private Sub Form_Resize()'这是原来form1中有的滚动块语句.
If Frame1.Height > Me.Height Then
VScroll1.Visible = True
Else
VScroll1.Visible = False
End If
If Frame1.Width > Me.Width Then
HScroll1.Visible = True
Else
HScroll1.Visible = False
End If
HScroll1.Left = 0
HScroll1.Top = Me.ScaleHeight - HScroll1.Height
VScroll1.Left = Me.ScaleWidth - VScroll1.Width
VScroll1.Top = 0
HScroll1.Width = Me.ScaleWidth
VScroll1.Height = Me.ScaleHeight
If VScroll1.Visible = True Then
If HScroll1.Visible = True Then
HScroll1.Width = Me.ScaleWidth - VScroll1.Width
VScroll1.Height = Me.ScaleHeight - HScroll1.Height
End If
End If
HScroll1.Max = (Frame1.Width - Me.Width) + 3 * VScroll1.Width
VScroll1.Max = (Frame1.Height - Me.Height) + 3 * HScroll1.Height
HScroll1.ZOrder
VScroll1.ZOrder

End Sub

Private Sub Form_Unload(Cancel As Integer)'这一段是鼠标滚轮加上的.
UnHook Me.hWnd
End Sub

Private Sub HScroll1_Change()'下面两段是form1原有的,滚动块语句.
Frame1.Left = -HScroll1.Value

End Sub

Private Sub VScroll1_Change()
Frame1.Top = -VScroll1.Value
End Sub