problem with multithreading and wrapper-class objects

[Ky.]

Hi guys,

I´m not sure I am using the corect terminology, since I´m pretty new to MFC programming. Sorry for that.

I created an object of a wrapper-class from an OCX libray (included with class _myObjectClass : public COleDispatchDriver).

As opposed to other classes in this library and what "OCX" suggests, this one is non-visual (no ActiveX).

I can use this object in a function just fine, except for when calling the function from a thread.


This works fine:

void TestDlg::DoIt()
{
_myObject m_obj;

m_obj.CreateDispatch("xxxx.xxxx");

m_obj.ObjMethod(xxx);
}


void TestDlg::OnButton()
{
DoIt();
}



But this does not

static UINT MyThread(LPVOID p);

UINT TestDlg::MyThread(LPVOID p)
{
TestDlg * app=(TestDlg *) p;

app->DoIt();

return 0;
}

void TestDlg::DoIt()
{
_myObject m_obj;

m_obj.CreateDispatch("xxxx.xxxx");

m_obj.ObjMethod(xxx);
}

void TestDlg::OnButton()
{
AfxBeginThread(MyThread, this);
}


Can anyone explain that behaviour or even suggest a solution?

Any advice or idea is greatly appreciated.

Thanks in advance,
..ky.


P.S. I already implemented a version, where PostMessage from MyThread calls the DoIt function, instead of calling it directly. It works, but it blocks my dialogue while DoIt is executed. But I need to run methods of m_obj while the main thread does other things...

[Arjay]

You need to call CoIniitialize/CoUninitiazed at the start/end of the thread proc. There may be other issues but for sure you need to at least initialize COM in the thread it is being used.

[Ky.]

Thanks a lot for your reply and for the catchwords. I´ll try and see what I can make out of that.

..Ky.

[Ky.]

Using CoInitalize and UnInitialize worked!

You saved my day, week and project.

Many many thanks,
..Ky.