CListView & HDN_ENDTRACK - there stay vertical lines
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Thread: CListView & HDN_ENDTRACK - there stay vertical lines

  1. #1
    Join Date
    Jul 2001
    Location
    Trutnov, Czech Republic
    Posts
    459

    CListView & HDN_ENDTRACK - there stay vertical lines

    Hi,
    in my CListView-derived class I added handler for HDN_ENDTRACKW notification, which looks like this:
    PHP Code:
    void CMyFileView::OnEndColumnResizing(NMHDRpNMHDRLRESULTpResult)
    {
        *
    pResult 0;

    The problem is, that now, after having added this handler, when I'm resizing any column (dragging the divider) and I finish dragging, there stays vertical line pointing from divider perpendicularly to the bottom of ListView. When I handle only HDN_BEGINTRACKW (and set *pResult to 0), everything is ok.

    What's the problem with that?

    Thank you.

  2. #2
    Join Date
    Apr 2014
    Posts
    1

    Re: CListView & HDN_ENDTRACK - there stay vertical lines

    After partying 10th anniversary of this problem I finally found a solution for it.

    Short story: call CWnd::Default from your HDN_ENDTRACK-handler

    Long story:
    Just recently I had the same problem and figured out that HDN_ENDTRACK is not only a notification for the end-user, but also a necessary message for the correct drawing (i.e. removing the vertical lines) of the parent list-ctrl: the drawing problem arises the moment you install an MFC-notify-handler for HDN_ENDTRACK.
    The difference is then in the function

    Code:
    // code from MFC: wincore.cpp lines 2133-2140 (MSVC 11, VS 2012)
    LRESULT CWnd::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
    {
        // OnWndMsg does most of the work, except for DefWindowProc call
        LRESULT lResult = 0;
        if (!OnWndMsg(message, wParam, lParam, &lResult))
            lResult = DefWindowProc(message, wParam, lParam);
        return lResult;
    }
    that for the HDN_ENDTRACK-notification OnWndMsg will return TRUE if and ony if there is a handler for it and thus, if there is a handler won't call DefWindowProc.
    As there doesn't exists a OnNotifyEx-handler (blame whoever you want) IMO the best way to handle it is calling CWnd::Default() from your HDN_ENDTRACK-handler.

    regards

    Tobias



    Quote Originally Posted by s_k View Post
    Hi,
    in my CListView-derived class I added handler for HDN_ENDTRACKW notification, which looks like this:
    PHP Code:
    void CMyFileView::OnEndColumnResizing(NMHDRpNMHDRLRESULTpResult)
    {
        *
    pResult 0;

    The problem is, that now, after having added this handler, when I'm resizing any column (dragging the divider) and I finish dragging, there stays vertical line pointing from divider perpendicularly to the bottom of ListView. When I handle only HDN_BEGINTRACKW (and set *pResult to 0), everything is ok.

    What's the problem with that?

    Thank you.

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