Question

I’m having a bug in my code that’s kicking my ass, so after much attempted debugging I finally decided to see if anyone else knew what my issue was.

I’m trying to add a grid object to a dialog that I have, but I keep hitting the assert mentioned in the title and I don’t know why.

LONG myDialog::OnInitDialog(UINT wParam, LONG lParam)
{
    BOOL bRet = super::OnInitDialog();

    InitGridControl();
    InitLayout();

    myApp.ActiveDocChangeEvent->Attach(
    RefMemberDelegate1(*this, &myDialog::OnNewDoc), this); // attach to event so I know when document is created

    return bRet;
}

void myDialog::OnNewDoc(CDerivedDocument* pNewDoc)
{
    pNewDoc->SetMyDialog(this); // when new document is created, set pointer to dialog
}

void myDialog::InitGridControl()
{
    CRect rect;
    // Get the grid area rectangle and set it up.
    GetDlgItem(IDC_GRID)->GetClientRect(rect);
    GetDlgItem(IDC_GRID)->MapWindowPoints(this, &rect); // replacing dummy image with the grid

    m_Grid = new myGridCtrl;
    bool result = m_Grid->Create(WS_CHILD | WS_BORDER | WS_VISIBLE | WS_TABSTOP, rect, this, IDC_GRID);


    // Set the appropriate options 
    //...options...

    m_Grid->InsertColumn(0, _T("Name"), 100); // doesn't seem to crash here, which means grid is created okay?
}


void myDialog::PopulateGridControl(BOOL bRedraw, CDerivedDocument * pDoc)
{
    if (GetSafeHwnd() == NULL)
        return;

    // get handles to document and stuff

    m_Grid->SetRedraw(FALSE); // ** ASSERT() CALL IS HERE **
    m_Grid->RemoveAll();

    // other stuff..
}


/////////////////////


// In CDocument, once it is created...

CDerivedDocument::SetMyDoc(myDialog * pDlg)
{
    pDlg->PopulateGridControl(true,this);
}

Any idea what’s going on? I mean, I only create the dialog once everything has been initialized, so there shouldn’t be a problem there. m_Grid.Create() returns true, so creation is successful. Why is SetRedraw() hitting the assert that the m_hWnd isn’t a handle to a window? Where does m_hWnd get set anyway?

Thanks for any help you can offer.

Cheers

Answer 1

Are you sure the dialog is created when you call
CDerivedDocument::SetMyDoc(myDialog * pDlg)?

What I see is that you are loading the grid (& dialog) from document, you should rather load the dialog and grid from the view using the document.

This may not be the direct cause of your assert trouble but nevertheless an improvement. It might just put things in the right order and fix this issue.