CATCH_ALL and OnCtlColor

[Coremn]

Hello I was trying to debug this code (see below), because after a few minutes it crashes. So I used a try{ }catch(...) to catch the exception but I dont know what type of exception it was. Is there a way to tell? I tried using TRY{} CATCH_ALL() but it dod not catch anything?? try{   DeleteObject(hbr); //must be deleted or eventually mem overflow    hbr = CDialog::OnCtlColor(pDC, pWnd, nCtlColor);    if (nCtlColor == CTLCOLOR_STATIC )    {      CWnd *Ctrl = GetDlgItem(pWnd->GetDlgCtrlID());      if (Ctrl)      {        CRect Rect;        Ctrl->GetWindowRect(&Rect);        this->ScreenToClient(&Rect);        COLORREF Clr = GetDC()->GetPixel(Rect.left-1, Rect.top-1);        hbr = CreateSolidBrush(Clr);        ASSERT(pDC);        if(!m_staticTextBgd)                 pDC->SetBkColor(Clr);        pDC->SetTextColor(RGB(m_fntR,m_fntG,m_fntB));        pDC->SetBkMode(m_staticTextBgd?OPAQUE:TRANSPARENT);      }   } } catch(...) { printf("Error"); } I tried catching CResourceException and CMemoryException and many others but it did not catch anything? How do I know what exception is being thrown? ---

[monrobot13]

Try catching a CException, that might work. If it does get the error message and it might help you figure out what type of exception is being thrown. - Aaron

[Coremn]

First thing I tried, it seems it does not throw a CException at all. I am sure it is a memory resource overflow problem, even though I am deleting my HBRUSH object. ---

[Coremn]

Appart from not knowing how to get infomation from an unknown exception, I have fixed my code problem. COLORREF Clr = GetDC()->GetPixel(Rect.left-1, Rect.top-1); This line does not like being called so often.(why??) So I just set Clr to the background color as it actually does not change after initilising it. Clr = RGB(m_bkR, m_bkG, m_bkB); cheers ---

[Ryan Binns]

There are a limited number of device contexts available at any one time. Every time this executes, you are locking one of these DCs with GetDC() but not releasing it with ReleaseDC(). Eventually, there will be no DCs available, and GetDC() will return NULL. Since you're not doing any error checking, you'll get a NULL-pointer exception while trying to call GetPixel().

Ryan

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