用VB编写一个弹出菜单类

'类的名称为cPopupMenu




Option Explicit


'


Private Type POINT


x As Long


y As Long


End Type


'


Private Const MF_ENABLED = &H0&


Private Const MF_SEPARATOR = &H800&


Private Const MF_STRING = &H0&


Private Const TPM_RIGHTBUTTON = &H2&


Private Const TPM_LEFTALIGN = &H0&


Private Const TPM_NONOTIFY = &H80&


Private Const TPM_RETURNCMD = &H100&


Private Declare Function CreatePopupMenu Lib "user32" () As Long


Private Declare Function AppendMenu Lib "user32" Alias "AppendMenuA" (ByVal hMenu As Long, ByVal wFlags As Long, ByVal wIDNewItem As Long, ByVal sCaption As String) As Long


Private Declare Function TrackPopupMenu Lib "user32" (ByVal hMenu As Long, ByVal wFlags As Long, ByVal x As Long, ByVal y As Long, ByVal nReserved As Long, ByVal hwnd As Long, nIgnored As Long) As Long


Private Declare Function DestroyMenu Lib "user32" (ByVal hMenu As Long) As Long


Private Declare Function GetCursorPos Lib "user32" (lpPoint As POINT) As Long


Private Declare Function GetForegroundWindow Lib "user32" () As Long


Private Declare Function GetMenuString Lib "user32" Alias "GetMenuStringA" (ByVal hMenu As Long, ByVal wIDItem As Long, ByVal lpString As String, ByVal nMaxCount As Long, ByVal wFlag As Long) As Long


Private mSelMenuString As String


Public Property Get SelMenuString() As String


SelMenuString = mSelMenuString


End Property


'


Public Function Popup(ParamArray param()) As Long


Dim iMenu As Long


Dim hMenu As Long


Dim nMenus As Long


Dim p As POINT




' get the current cursor pos in screen coordinates


GetCursorPos p




' create an empty popup menu


hMenu = CreatePopupMenu()




' determine # of strings in paramarray


nMenus = 1 + UBound(param)




' put each string in the menu


For iMenu = 1 To nMenus


' the AppendMenu function has been superseeded by the InsertMenuItem


' function, but it is a bit easier to use.


If Trim$(CStr(param(iMenu - 1))) = "-" Then


' if the parameter is a single dash, a separator is drawn


AppendMenu hMenu, MF_SEPARATOR, iMenu, ""


Else


AppendMenu hMenu, MF_STRING + MF_ENABLED, iMenu, CStr(param(iMenu - 1))


End If


Next iMenu




' show the menu at the current cursor location;


' the flags make the menu aligned to the right (!); enable the right button to select


' an item; prohibit the menu from sending messages and make it return the index of


' the selected item.


' the TrackPopupMenu function returns when the user selected a menu item or cancelled


' the window handle used here may be any window handle from your application


' the return value is the (1-based) index of the menu item or 0 in case of cancelling


iMenu = TrackPopupMenu(hMenu, TPM_RIGHTBUTTON + TPM_LEFTALIGN + TPM_NONOTIFY + TPM_RETURNCMD, p.x, p.y, 0, GetForegroundWindow(), 0)


Dim result As Long


Dim buffer As String


Const MF_BYPOSITION = &H400&




buffer = Space(255)




result = GetMenuString(hMenu, (iMenu - 1), buffer, _


Len(buffer), MF_BYPOSITION)


'Debug.Print buffer


mSelMenuString = Trim(buffer)


' release and destroy the menu (for sanity)


DestroyMenu hMenu




' return the selected menu item's index


Popup = iMenu




End Function




'结束




'以下是实例，在Form上添加一个ListBox控件




Option Explicit




Private Sub Form_Load()


List1.AddItem "Right-Click here for a menu"


End Sub




Private Sub List1_MouseUp(Button As Integer, Shift As Integer, x As Single, y As Single)


Dim oMenu As cPopupMenu


Dim lMenuChosen As Long


'


If Button = vbRightButton Then


Set oMenu = New cPopupMenu


'


' Pass in the desired menu, use '-' for a separator


'


lMenuChosen = oMenu.Popup("Menu 1", "Menu 2", "Menu 3", _


"-", "Menu 4")


'


Debug.Print lMenuChosen


Debug.Print oMenu.SelMenuString


End If




'


End Sub