reflection, base class private properties, etc.

[Sunny]

Hi,
I have an old problem which I couldn't solve so far. Now I have found a post
in that group that gave me an idea, but I can not fully understand it.
The problem is: I'm trying to use a Windows.Forms.U serControl in a COM
environment, i.e. I want to host that control in a COM host. So far, so
good, I can host it, but I can not reach the parent COM object from the
control (Parent property is null :( ).
I have stopped the control in the debugger and I found in the watch window
some properties, like ActiveXInstance
{System.Windows .Forms.Control. ActiveXImpl}
The problem is that they are private to the base class, so I can not access
them.

Now the question: is it possible somehow to access these base properties
programmaticall y. I have found a post which mentions something about
reflection (whatever that mean). Can I use a reflection to access these
properties?

Any help will be highly appreciated.

Thanks
Sunny

[Chris Peacock]

Your code has been really helpful to me, as I encountered exactly the
same problem as Sunny (i.e. adding property pages to Outlook), except
that I'm using VB.NET. I thought that anyone trying to achieve this
may be interested to know that the code can be simplified to the
following:-

Public ReadOnly Property PageSite() As PropertyPageSit e
Get
Dim typeUnsafeNativ eMethods As Type = GetType
_(Windows.Forms .Control).Assem bly.GetType
_("System.Windo ws.Forms.Unsafe NativeMethods")
Dim typeOleObject As Type =
typeUnsafeNativ eMethods.GetNes tedType _("IOleObject ")
Dim methodGetClient Site As Reflection.Meth odInfo = _
typeOleObject.G etMethod("GetCl ientSite")
Dim site As Object = methodGetClient Site.Invoke(Me,
Nothing)

Try
Return CType(site, PropertyPageSit e)
Catch ex As InvalidCastExce ption
'Handle the exception
End Try
End Get
End Property

The above PageSite property is added to your class that implements the
Outlook.Propert yPage interface.

One further necessity though, will probably be to set the caption of
the property page (the tab heading). In order to do this, I found that
I had to define my own interface as follows (substitute a GUID where
the x's are):-

<GuidAttribute( "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"),
InterfaceTypeAt tribute _ (ComInterfaceTy pe.InterfaceIsI Dispatch)> _
Public Interface IMyProperties
Inherits PropertyPage
<DispId(-518)> ReadOnly Property Caption() As String
End Interface

Instead of implementing Outlook.Propert yPage, your class would then
implement IMyProperties.

"Sunny" <su******@icebe rgwireless.com> wrote in message news:<O0******* *******@TK2MSFT NGP10.phx.gbl>. ..

Hi Vladimir,
IT WORKS IT WORKS. You are great. I have implemented this in C# and it gave
me the reference I needed. I suppose, that I had to implement all of your
code, but I stopped at the check for site is Nothing, because I can cast it
at the type I want. So, I do not know what the rest of the code have to do.
If you have a little time, pls, explain. Nevertheless so far, you are the
only guy around who have succeeded to solve that problem. I have posted it
allover, with different ideas, but ... nothing.

Thank you again
Sunny

"Vladimir Kouznetsov" <vl************ *****@REMOVETHI Sngrain.com> wrote in
message news:O9******** ******@TK2MSFTN GP09.phx.gbl...

Here is a sample code (in VB but it shouldn't not be difficult to

translate

it) I used to get UserMode property:

Dim strAssembly As String
strAssembly =
Type.GetType("S ystem.Object"). Assembly.CodeBa se.Replace("msc orlib.dll",
"System.Windows .Forms.dll")
strAssembly = strAssembly.Rep lace("file:///", String.Empty)
strAssembly =

Reflection.Asse mblyName.GetAss emblyName(strAs sembly).FullNam e

Dim unmt As Type = _
Type.GetType(Re flection.Assemb ly.CreateQualif iedName(strAsse mbly,
"System.Windows .Forms.UnsafeNa tiveMethods"))
Dim ioot As Type = unmt.GetNestedT ype("IOleObject ")
Dim mi As Reflection.Meth odInfo = ioot.GetMethod( "GetClientSite" )
Dim site As Object = mi.Invoke(Me, Nothing)
If site Is Nothing Then Return -1

' We are hosted by a COM container

Dim dsite As IDispatch = site

' All the uninitialized arguments work fine in this case
Dim id As Guid
Dim params As DISPPARAMS
Dim lcid As System.UInt32
Dim wFlags As System.UInt16 = System.UInt16.P arse(2.ToString ())
Dim result As Object
dsite.Invoke(-709, id, lcid, wFlags, params, result, Nothing, Nothing)

If result Then
Return 1
Else
Return 0
End If

That should give you an idea how to do what you want. IIRC IOleClientSite
has method GetContainer() which I think you need (not the parent COM
object). BTW You can use ildasm on System.Windows. Forms.dll to make

yourself

familiar with the internal classes and implementations .

thanks,
v

"Sunny" <su******@icebe rgwireless.com> wrote in message
news:ui******** ******@tk2msftn gp13.phx.gbl...

Hi, it seems that I have to guess what property to get, so I'll play with all of them, but that happen always with combination COM/.Net/Outlook :)
The problem is, that I have read some of docs for reflection, and I still have no idea where to start and how to access these private members :(
So any example will be helpful.

Sunny

"Ignacio Machin" <ignacio.mach in AT dot.state.fl.us > wrote in message
news:ul******** ********@TK2MSF TNGP12.phx.gbl. ..
> Hi Sunny,
>
>
> I think that yes, it's possible to access the private properties of a class > using reflection, I haven't tested it but I also saw the post of Nicholas > and until now all that he said is true ;) , the thing is ( also stated in > the post ) what are you planning to do with it? it;s a private property
and > you have no idea of how it's used or what it means.
>
> Cheers,
>
> --
> Ignacio Machin,
> ignacio.machin AT dot.state.fl.us
> Florida Department Of Transportation
>
> "Sunny" <su******@icebe rgwireless.com> wrote in message
> news:uO******** *****@tk2msftng p13.phx.gbl...
> > Hi,
> > I have an old problem which I couldn't solve so far. Now I have found
a
post > > in that group that gave me an idea, but I can not fully understand it. > > The problem is: I'm trying to use a Windows.Forms.U serControl in a COM > > environment, i.e. I want to host that control in a COM host. So far, so > > good, I can host it, but I can not reach the parent COM object from the > > control (Parent property is null :( ).
> > I have stopped the control in the debugger and I found in the watch window > > some properties, like ActiveXInstance
> > {System.Windows .Forms.Control. ActiveXImpl}
> > The problem is that they are private to the base class, so I can not access > > them.
> >
> > Now the question: is it possible somehow to access these base properties > > programmaticall y. I have found a post which mentions something about
> > reflection (whatever that mean). Can I use a reflection to access these > > properties?
> >
> > Any help will be highly appreciated.
> >
> > Thanks
> > Sunny
> >
> >
>
>