Question

I have a simple CMFCRibbonProgressBar and a thread that calls SetPos(value, TRUE) on it when a lengthy operation progresses.
The problem is that in debug mode it asserts in wincore.cpp with this:

    CHandleMap* pMap = afxMapHWND();
    ASSERT(pMap != NULL);

I understand by the comments in that file that I shouldn’t be calling it from a different thread because it could potentially be dangerous.
My question then is how do you get a thread to update the position of the progress bar ?
I’m very tempted to just ignore that assert and continue in release mode but that’s pretty evil…

Any suggestions ?

Answer 1

Ok, someone commented very briefly on the question and they had the right answer. I don’t know why they retracted their comment :/

I ended up storing a CWnd* pointer in the CMFCRibbonProgressBar derived class, and whenever I call the “SetAmountCompleted” method from the worker thread, I use the CWnd to send a custom message with a pointer to the derived class in the WPARAM.
The CWnd that receives the message then extracts the pointer and calls Update method which will redraw the progress bar.

It’s complicated, it’s ugly, it’s MFC. Phew.