Screen Capture

#define PW_WINDOW          9001
#define PW_CLIENT             9002

HBITMAP CMyProgramDlg::CopyScreenToBitmap(LPRECT lpRect)
{
	HDC         hScrDC, hMemDC;         // screen DC and memory DC
	int         nX, nY, nX2, nY2;       // coordinates of rectangle to grab
	int         nWidth, nHeight;        // DIB width and height
	int         xScrn, yScrn;           // screen resolution      

	HGDIOBJ     hOldBitmap , hBitmap;

		// check for an empty rectangle
    if (IsRectEmpty(lpRect))
	   return NULL;
	   // create a DC for the screen and create
	   // a memory DC compatible to screen DC          

   hScrDC = CreateDC("DISPLAY", NULL, NULL, NULL);
   hMemDC = CreateCompatibleDC(hScrDC);      // get points of rectangle to grab  

   nX = lpRect->left;
   nY = lpRect->top;
   nX2 = lpRect->right;
   nY2 = lpRect->bottom;      // get screen resolution      

   xScrn = GetDeviceCaps(hScrDC, HORZRES);
   yScrn = GetDeviceCaps(hScrDC, VERTRES);      

   //make sure bitmap rectangle is visible      

   if (nX < 0)
	  nX = 0;     

   if (nY < 0)
      nY = 0;     

   if (nX2 > xScrn)
      nX2 = xScrn;     

   if (nY2 > yScrn)
      nY2 = yScrn;      

   nWidth = nX2 - nX;
   nHeight = nY2 - nY;      

   // create a bitmap compatible with the screen DC     

   hBitmap = CreateCompatibleBitmap(hScrDC, nWidth, nHeight);      

   // select new bitmap into memory DC     

   hOldBitmap =   SelectObject (hMemDC, hBitmap);      

   // bitblt screen DC to memory DC     

   BitBlt(hMemDC, 0, 0, nWidth, nHeight, hScrDC, nX, nY, SRCCOPY);     

   // select old bitmap back into memory DC and get handle to
   // bitmap of the screen          

   hBitmap = SelectObject(hMemDC, hOldBitmap);      

   // clean up      

   DeleteDC(hScrDC);
   DeleteDC(hMemDC);      

   // return handle to the bitmap      

   return (HBITMAP)hBitmap;
}

HBITMAP CYourProgramDlg::CopyWindowToBitmap(CWnd* wnd , HWND hWnd, WORD fPrintArea)
{
	HBITMAP     hBitmap = NULL;  // handle to device-dependent bitmap
	// check for a valid window handle
	if (!hWnd)
	    return NULL; 

    RECT    rectWnd;
    ::GetWindowRect(hWnd, &rectWnd);  

	switch (fPrintArea)
	{
		case PW_WINDOW: // copy entire window
		{
          // get the window rectangle
          // get the bitmap of that window by calling
		  // CopyScreenToBitmap and passing it the window rect
//		  GetWindowRect(&rectWnd);
		  hBitmap = CopyScreenToBitmap(&rectWnd);
		  break;
		}
       case PW_CLIENT: // copy client area
	   {
	     RECT rectClient;
	     POINT pt1, pt2;              // get client dimensions
	     wnd->GetClientRect(&rectClient);              // convert client coords to screen coords
	     pt1.x = rectClient.left;
	     pt1.y = rectClient.top;
	     pt2.x = rectClient.right;
	     pt2.y = rectClient.bottom;
	     wnd->ClientToScreen(&pt1);
	     wnd->ClientToScreen(&pt2);
	     rectClient.left = pt1.x;
	     rectClient.top = pt1.y;
	     rectClient.right = pt2.x;
	     rectClient.bottom = pt2.y;  

         // get the bitmap of the client area by calling
	     // CopyScreenToBitmap and passing it the client rect
	     hBitmap = CopyScreenToBitmap(&rectClient);
	     break;
	   }
	   default:    // invalid print area
	        return NULL;
	}      // return handle to the bitmap     

	return hBitmap;
}

http://forums.codeguru.com/showthread.php?244907-Screen-Capture