Re: How to use callback in a MFC DLL in .NET program?

From:

"Z.K." <nospam@nospam.net>

Newsgroups:

microsoft.public.vc.mfc

Date:

Wed, 21 Jun 2006 22:45:36 -0700

Message-ID:

<u5KsP8blGHA.4716@TK2MSFTNGP04.phx.gbl>

TimPlyr wrote:

Dear all,
This may not be the right place to ask this question but it is MFC related:

I have a DLL developed in VS6 using MFC, one of the function is this:
void API::startScan(void (__stdcall *lpfn)(void *status)) {
...
}

lpfn is a callback function supplied by caller(in this case, a function in
my .NET C++ program), status is a pointer to a complex structure inside the
DLL.
I need to copy the data pointed by status in the callback function.

Now I am developing application in VS2005 using .NET CLR
My question is how to implement the callback function and allocate memory
for the structured data for the DLL?

I have tried:

public delegate void delAPI(void *param);
...

       delAPI ^delAPIinst;
       if(delAPIinst) {
        delAPIinst(&i);
       }

       delAPIinst = gcnew delAPI(this, &Form1::fromAPI);

       obj->startScan(delAPIinst);

but the compiler complains:
error C2664: 'API::startScan' : cannot convert parameter 1 from
'tmydll::delAPI ^' to 'void (__stdcall *)(void *)'

Can anyone help me out?

Thanks and best regards,

Tim

Tim;

I just had a similar problem which is not that easy to figure out in
MFC or at least not for me. I just had this discussion dated 6-18-2006
and you might check that out and see if it gives you any ideas.
Basically, you need to use a static function. Frank Hickman was quite
helpful in helping me resolve my problem which sounds similar to the
problem that you are having.

Z.K.