I'm confused by documentation and examples on using Delegate to create
Events for use with COM
In some situation I see a parameter list of (sender as Object, e as
EventArgs) and other times I see no parameters, or a list of parameters that
are event dependent.
Below is my .NET code to create a class which raises some events.
From C++ (using MFC 6.0) I create an instance of the object and
IConnectionPoin tContainer which seems to work.
When the .NET object raises the event I get an exception of type
System.NullRefe renceException: Object reference not set to an instance of an
object.
at MapiForm._FormE vents.Shutdown( )
at MapiForm.MAPIFo rm.frm_ShutDown Form() in D:\My
Documents\SQLVi ew\Forms\MAPIFo rm\MAPIForm.vb: line 63
at MapiForm.Outloo kForm.txtShutdo wn_Click(Object sender, EventArgs e) in
D:\My Documents\SQLVi ew\Forms\MAPIFo rm\OutlookForm. vb:line 113
at System.Windows. Forms.Control.O nClick(EventArg s e)
at System.Windows. Forms.Button.On Click(EventArgs e)
at System.Windows. Forms.Button.On MouseUp(MouseEv entArgs mevent)
at System.Windows. Forms.Control.W mMouseUp(Messag e& m, MouseButtons
button, Int32 clicks)
at System.Windows. Forms.Control.W ndProc(Message& m)
at System.Windows. Forms.ButtonBas e.WndProc(Messa ge& m)
at System.Windows. Forms.Button.Wn dProc(Message& m)
at System.Windows. Forms.ControlNa tiveWindow.OnMe ssage(Message& m)
at System.Windows. Forms.ControlNa tiveWindow.WndP roc(Message& m)
at System.Windows. Forms.NativeWin dow.Callback(In tPtr hWnd, Int32 msg,
IntPtr wparam, IntPtr lparam)
*************** ****
Any ideas how I need to setup events so that I can call them from MFC 6.0
???
Thanks!
*************** ***
----------- snip -------------
Imports System
Imports System.Runtime. InteropServices
<ComVisible(Fal se)> Public Delegate Sub NewMessageEvent Handler()
<ComVisible(Fal se)> Public Delegate Sub ShutdownEventHa ndler()
<ComVisible(Fal se)> Public Delegate Sub PrintEventHandl er()
<ComVisible(Fal se)> Public Delegate Sub SavedEventHandl er()
<GuidAttribute( "93D44286-4BA4-4cc7-8971-0C7831EA0354"),
InterfaceTypeAt tribute(ComInte rfaceType.Inter faceIsDual)> _
Public Interface _Form
<DispId(&H1001) > Sub ShowForm(ByVal sCN As String, ByVal sGUID As
String)
<DispId(&H1002) > Sub ShutDownForm(By Val SaveOptions As UInt32)
<DispId(&H1003) > Sub DoVerb(ByVal Verb As Int32)
End Interface
<GuidAttribute( "06670E52-A3C2-480b-8D7A-7CE3DD1D03A3"),
InterfaceTypeAt tribute(ComInte rfaceType.Inter faceIsDual)> _
Public Interface _FormEvents
<DispId(&HF001) > Sub NewMessage()
<DispId(&HF002) > Sub Shutdown()
<DispId(&HF003) > Sub Print(ByVal PageNumber As UInt32, ByVal Status As
UInt32)
<DispId(&HF004) > Sub Saved()
End Interface
' This is your COM object, you must implement _Form and _FormEvents
' For each object that you create you will need to assign a unique GUID
' and give the class a unique ProgID
<GuidAttribute( "9d8a13bf-df52-3084-954b-95e85887111d"),
ProgIdAttribute ("SQLView.Form" ), ClassInterface( ClassInterfaceT ype.None),
ComSourceInterf aces(GetType(_F ormEvents))> _
Public Class MAPIForm
Implements _Form
Public Event NewMessage As NewMessageEvent Handler
Public Event ShutDown As ShutdownEventHa ndler
Public Event Print As PrintEventHandl er
Public Event Saved As SavedEventHandl er
Private WithEvents frm As New OutlookForm
' A creatable COM class must have a Public Sub New()
' with no parameters, otherwise, the class will not be
' registered in the COM registry and cannot be created
' via CreateObject.
Public Sub New()
MyBase.New()
End Sub
Public Sub ShowForm(ByVal sCN As String, ByVal sGUID As String)
Implements _Form.ShowForm
' This is called by Outlook when a form needs to be displayed
frm.txtCON.Text = sCN
frm.txtGUID.Tex t = sGUID
frm.Show()
End Sub
Public Sub ShutDownForm(By Val SaveOptions As UInt32) Implements
_Form.ShutDownF orm
' The is called by Outlook when it wants to close the form
End Sub
Public Sub DoVerb(ByVal Verb As Int32) Implements _Form.DoVerb
' The is called by Outlook when a verb (eg Print) needs to be done
' Verbs are defined in the cfg file
End Sub
Private Sub frm_ShutDownFor m() Handles frm.ShutDownFor m
RaiseEvent ShutDown()
End Sub
End Class
-----------------------------
--
Michael Tissington
http://www.oaklodge.com
http://www.tabtag.com
