Re: Multiple BitBlts Eventually Crash. Why?

I'm calling the following function in a timer. It draws a specific bitmap
from an array of bitmaps (animation approach)

After a few hundred calls I get an unhandled exception 0xC0000005 Access
Violation. When I try to debug it drops me on the line
"memDC.SelectObject(pOldBitmap) ;" and I see that pOldBitmap is
0x00000000.
What's going on?

   - Mark

CBitmap m_bitmapArray[MAX_BITMAPS] ; // is defined in the class
the argument "nRef" is the reference to an array of bitmaps

///////////////////////////////////////////////////////////////////////////////
void CMyCtrl::ShowBitmapInRect (CDC *pDC, CRect rectTarget, int nRef)
{
   if ((rectTarget.Width() != m_rectDraw.Width()) &&
       (rectTarget.Height() != m_rectDraw.Height()))
       return ;

   if ((nRef < 0) || (nRef >= m_nSteps))
       return ;

   // make memory dc
   CDC memDC ;
   memDC.CreateCompatibleDC(pDC) ;

   // grab the bitmap
   CBitmap *pOldBitmap = memDC.SelectObject(&m_bitmapArray[nRef]) ;

   // draw the memory dc
   pDC->BitBlt(rectTarget.left, rectTarget.top,
   rectTarget.Width(), rectTarget.Height(),
   &memDC, 0, 0, SRCCOPY) ;

   // release the bitmap
   memDC.SelectObject(pOldBitmap) ;

} //ShowBitmapInRect