Overcome Window Flicker While Dragging

While I use the CImageList control for dragging, I found it flickers in the owner window while draging and redraw the client region. I tried Google to find a solution, but there were no result, so I try to solve it myself.

Here's my solution, which I'm very glad share with you!

First, you should register a new window class and create a new top most tool window, and move it's position far off screen(I take 99000), so it's not visible. The code would look like this:

BOOL CImageDragWrapper::Initialize()
      return TRUE;

   wcex.cbSize = sizeof(WNDCLASSEX); 

   if(!::GetClassInfoEx(AfxGetInstanceHandle(), POPWINDOWCLASSNAM, &wcex))
      wcex.style           = CS_HREDRAW | CS_VREDRAW;
      //specifies default window procedure 
      wcex.lpfnWndProc     = (WNDPROC)DefWindowProc;
      wcex.cbClsExtra      = 0;
      wcex.cbWndExtra      = 0;
      wcex.hInstance       = AfxGetInstanceHandle();
      wcex.hIcon           = LoadIcon(0, IDI_INFORMATION);
      wcex.hCursor         = LoadCursor(NULL, IDC_ARROW);
      wcex.hbrBackground   = (HBRUSH)(COLOR_WINDOW+1);
      wcex.lpszMenuName    = 0;
      wcex.lpszClassName   = POPWINDOWCLASSNAM;
      wcex.hIconSm         = LoadIcon(0, IDI_INFORMATION);   

                        _T(""),WS_POPUP | WS_DISABLED |  WS_CLIPSIBLINGS,99000, 
                        0, 6, 6, 0,   0,
                        AfxGetInstanceHandle(),   0   );

      SetLayeredWindowAttributes(RGB(255,255,255), 100,   /*0x00000001|*/0x0000002);

      ShowWindow(m_hDragWnd, SW_SHOW);
   return m_hDragWnd != 0;

Second, move the window to properly position and paint it's client. The code would look like this:

BOOL CImageDragWrapper::DragBegin(HWND hDragWndOwner,int cxWnd, int cyWnd, 
                int cxHotSpotOffset, int cyHotSpotOffset,
                const POINT& ptCurrentMousePos, HBITMAP hBack, 
				int cxBackOffset, int cyBackOffset)
      m_hDragWndOwner = hDragWndOwner;
      m_cxHotSpotOffset = cxHotSpotOffset;
      m_cyHotSpotOffset = cyHotSpotOffset;

      POINT ptDest = ptCurrentMousePos;
      ClientToScreen(m_hDragWndOwner, &ptDest);

                ptDest.x - m_cxHotSpotOffset, 
                ptDest.y - m_cyHotSpotOffset, 
                cyWnd, TRUE);

      //Draw background image for dragging support window
         HDC hDC = ::GetDC(m_hDragWnd);
         HDC hMemDC = ::CreateCompatibleDC(hDC);
         HBITMAP hbmpOldMem = (HBITMAP)::SelectObject(hMemDC, hBack);
         ::BitBlt(hDC, 0, 

         ::SelectObject(hMemDC, hbmpOldMem);

         ::ReleaseDC(m_hDragWnd, hDC);
   return m_hDragWnd != 0;

Third, changes the position and dimensions for dragging support window by calling MoveWindow

Forth, move dragging to support the window's postion far to screen. The code would look like this:

BOOL CImageDragWrapper::DragEnd()
   if(m_hDragWnd && m_hDragWndOwner)
      m_hDragWndOwner = 0;
                   6, TRUE);
   return m_hDragWnd != 0;

Using the Code:

First, in the InitInstance method of CWinApp's subclass add code like this:

   CTestDragDialogDlg dlg;
   m_pMainWnd = &dlg;
   int nResponse = dlg.DoModal();
   if (nResponse == IDOK)
      // TODO: Place code here to handle when the dialog is
      //  dismissed with OK
   else if (nResponse == IDCANCEL)
      // TODO: Place code here to handle when the dialog is
      //  dismissed with Cancel


Then in dragging the owner window's OnMouseMove, OnLButtonUp method calls DragBegin, DragMove, and DragEnd method of CImageDragWrapper, It's very simple.

Note: you can compare CImageDragWrapper with CImageList by using my sample code!

About the Author

Jehhry23 Lv

I'm come from china, very glad to make friend with you!



  • Is Penis Enlargement an Option to Erectile Dysfunction?

    Posted by anueffifielm on 06/21/2013 12:54am

    Erectile Dysfunction - Is it Psychological? It is also widely spread and well known in many countries [url=http://rxhealth.pw ] how long will an erection last with viagra [/url] read far more Erectile Malfunction and Impotence, Avoid Taboo See How

Leave a Comment
  • Your email address will not be published. All fields are required.

Top White Papers and Webcasts

  • Power and Automation Equipment makers face constrained CAPEX, equipment interoperability issues, and process inefficiencies. However, they can take advantage of secure Internet of Things (IoT) intelligent devices and systems to make better business decisions around asset utilization and performance, while simultaneously optimizing equipment interoperability and services efficiency. Watch this brief video to see how you can unlock the full potential of your assets and value chain.

  • Lenovo recommends Windows 8 Pro. "I dropped my laptop getting out of the taxi." This probably sounds familiar to most IT professionals. If your employees are traveling, you know their devices are in for a rough go. Whether it's a trip to the conference room or a convention out of town, any time equipment leaves a user's desk it is at risk of being put into harm's way. Stay connected at all times, whether at the office or on the go, with agile, durable, and flexible devices like the Lenovo® …

Most Popular Programming Stories

More for Developers

RSS Feeds

Thanks for your registration, follow us on our social networks to keep up-to-date