在MapX中响应滚轮放大缩小地图

’模块中

Option Explicit

Public Const GWL_WNDPROC = (-4)

Public Const WM_COMMAND = &H111

Public Const WM_MBUTTONDOWN = &H207

Public Const WM_MBUTTONUP = &H208

Public Const WM_MOUSEWHEEL = &H20A

Public Oldwinproc As Long

Public Declare Function SetWindowLong Lib 'user32' Alias 'SetWindowLongA' (ByVal hWnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long

Public 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

Public Declare Function GetWindowLong Lib 'user32' Alias 'GetWindowLongA' (ByVal hWnd As Long, ByVal nIndex As Long) As Long

Public Function FlexScroll(ByVal hWnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long

Select Case wMsg

Case WM_MOUSEWHEEL

Select Case wParam

Case -7864320 '向下滚

SetCurrentScale 'ZoomOut', 2

Case 7864320 '向上滚

SetCurrentScale 'ZoomIn', 2

End Select

End Select

FlexScroll = CallWindowProc(Oldwinproc, hWnd, wMsg, wParam, lParam)

End Function

Private Sub SetCurrentScale(strINorOut As String, dScale As Double)

If frmMain.Map1 Is Nothing Then Exit Sub

If strINorOut = 'ZoomIn' Then

frmMain.Map1.Zoom = (frmMain.Map1.Zoom) * dScale

frmMain.Map1.Refresh

ElseIf strINorOut = 'ZoomOut' Then

frmMain.Map1.Zoom = (frmMain.Map1.Zoom) / dScale

frmMain.Map1.Refresh

End If

End Sub

Private Sub Form_Load()

Oldwinproc = GetWindowLong(Map1.hWnd, GWL_WNDPROC)

SetWindowLong Map1.hWnd, GWL_WNDPROC, AddressOf FlexScroll

End Sub

Private Sub Form_Unload(Cancel As Integer)

SetWindowLong Map1.hWnd, GWL_WNDPROC, Oldwinproc

End Sub