Questions about using Active X controls in C#

Question

Hi,

I am trying to use a activeX control in C#. I add the control to references.
I need to call one of the function of the ActiveX Obj. I got confused here.

It was defined as 
   **.Register(int hWndCtrl, object Flags); 

VC++ provided sample as 

    HWND hwndTop = GetDlgItem( IDC_EDITTOP );
    hRes = m_pIDgnDictEditTop->Register( (long)hwndTop, CComVariant() );

In VC#, 

I used this,

   ...
   private System.Windows.Forms.TextBox edtRaw;

   ...

   Form1_load()
   {
      ......
      System.Object a;
      a = 0;
      dictEdit.Register(( (System.Int32)edtRaw.Handle, a);
      ......
   }

No error, no warning while building the sln. But got error during excution at the Register code,
An unhandled exception of type 'System.Runtime.InteropServices.COMException' occurred in DragonIDX.exe

Additional information: COM returned an unexpected error code: Details are E_UNEXPECTED 

Questions:
1) Do I have the right Window Handle in C#?
2) What is the thing corresponding to CCOMVariant in C#?

Thanks a lot.
Pin
    

Answer 1

Try tinkering with your cast, try casting it to System.Int16, Int64 or just simply int...

What does the intellisense tells you about the parameter on dicEdit.Register()?




cheers,


Paul June A. Domag

Answer 2

Pin wrote:

Hi, I am trying to use a activeX control in C#. I add the control to references. I need to call one of the function of the ActiveX Obj. I got confused here. It was defined as     **.Register(int hWndCtrl, object Flags);  VC++ provided sample as      HWND hwndTop = GetDlgItem( IDC_EDITTOP );     hRes = m_pIDgnDictEditTop->Register( (long)hwndTop, CComVariant() ); In VC#,  I used this,    ...    private System.Windows.Forms.TextBox edtRaw;    ...    Form1_load()    {       ......       System.Object a;       a = 0;       dictEdit.Register(( (System.Int32)edtRaw.Handle, a);       ......    } No error, no warning while building the sln. But got error during excution at the Register code, An unhandled exception of type 'System.Runtime.InteropServices.COMException' occurred in DragonIDX.exe Additional information: COM returned an unexpected error code: Details are E_UNEXPECTED  Questions: 1) Do I have the right Window Handle in C#? 2) What is the thing corresponding to CCOMVariant in C#? Thanks a lot. Pin

Pin,

   The second parameter is of type object, but in COM, this represents the VARIANT, which allows for anything to be passed.  However, it is completely possible that the code inside the method expects something different than the int that you are passing.

   I would try sending System.Reflection.Missing.Value (I believe that is it), and seeing what happens.

   Unfortunately, the E_UNEXPECTED error code is not very descriptive.

   Hope this helps.

          - Nicholas Paldino [.NET/C# MVP]
          - [e-mail]

Answer 3

Thanks,

Nicholas' advice works for it. Thanks. But I am not sure the reason to put the "...Missing.Value"? How do I know this if I did not post my question here? Is it described in any section of general C#  cookbooks?

Thanks a lot.
Pin

Answer 4

Pin wrote:

Thanks, Nicholas' advice works for it. Thanks. But I am not sure the reason to put the "...Missing.Value"? How do I know this if I did not post my question here? Is it described in any section of general C#  cookbooks? Thanks a lot. Pin

Pin,

   The reason this happens is because of the differences between COM and .NET.  COM does not allow for overloading on methods, however, it does allow for optional parameters, which .NET does not.

   So, when you expose a method in COM with optional parameters to .NET, they are always visible in .NET.  Because of this, if you don't want to pass those parameters, you have to pass System.Missing.Value.

          - Nicholas Paldino [.NET/C# MVP]
          - [e-mail]