Re: CDC does not Work Properly

From:

"AliR $VC++ MVP$" <AliR@online.nospam>

Newsgroups:

microsoft.public.vc.mfc

Date:

Wed, 30 Jan 2008 18:02:18 GMT

Message-ID:

<KY2oj.8741$Ej5.775@newssvr29.news.prodigy.net>

How was m_pProcDC created!!!

AliR.

"Matrixinline" <anup.kataria@gmail.com> wrote in message
news:bafbdaa4-d22a-44ee-b29b-5937952cc07d@q21g2000hsa.googlegroups.com...

In a Dialog based application I have OnPaint method like this

///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
CDC *pDC = GetDC();
               CDC oTempDC;
                oTempDC.CreateCompatibleDC(m_pProcDC);

oTempDC.BitBlt (0, 0, screenMaxX, screenMaxY, m_pProcDC, 0, 0,
SRCCOPY );
// m_pProcDC is CDC and contains a Bitmap as selected object
oTempDC.DrawIcon(oRect.left, oRect.top, m_hIcon);
// Loaded ICON from resource m_hIcon
pDC->BitBlt(0, 0, screenMaxX, screenMaxY,&oTempDC, 0, 0, SRCCOPY);
ReleaseDC(pDC);
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

it diaplays Nothing!! id displays only the background color of dialog
nothing else.
If I replace the code

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
CDC *pDC = GetDC();
               // m_pProcDC is CDC and contains a Bitmap as selected
object
pDC->BitBlt(0, 0, screenMaxX, screenMaxY,m_pProcDC, 0, 0, SRCCOPY);
ReleaseDC(pDC);
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////
it works!!

Can you please let me know why it is displaying anything?

Thanks
Anup