MFC List Control scrolling shows extra grid lines

Answer 1

Is this happening with the stock listview, or is it custom draw? I've never seen redrawing issues with the standard windows controls.

Maybe you can post a screenshot to illustrate the problem? I presume you'd prefer to fix the redraw issue and not size the control exactly?

Answer 2

I recall this being a bug in the ListView (not just through MFC, but the common control in general) itself. A quick google on this seems to hit a lot of people coming to that same conclusion. I guess since Windows Explorer doesn't have gridlines they don't feel the need fix this? I remember this back in the late 90's.

I guess the trick would be to invalidate the window after a scroll - maybe in response to a VSCROLL message? Just a guess.

Answer 3

This is indeed a bug related to "smooth scrolling," here's a workaround:

void CMyListCtrl::OnVScroll(UINT nSBCode, UINT nPos, CScrollBar* pScrollBar)
{
    __super::OnVScroll(nSBCode, nPos, pScrollBar);
    Invalidate();
    UpdateWindow();
}

Answer 4

To fix this bug in the MFC List Control you need to specialize the control, over-ride the method wich responds to the scroll, and force it to redraw the list completely after it has done the scroll.

interface header

class cSmoothListControl : public CListCtrl
{
public:
    DECLARE_MESSAGE_MAP()
    afx_msg void OnVScroll(UINT nSBCode, UINT nPos, CScrollBar* pScrollBar);
};

implementation:

BEGIN_MESSAGE_MAP(cSmoothListControl, CListCtrl)
ON_WM_VSCROLL()
END_MESSAGE_MAP()

void cSmoothListControl::OnVScroll(UINT nSBCode, UINT nPos, CScrollBar* pScrollBar)
{
    // call base class method to do scroll
    CListCtrl::OnVScroll(nSBCode, nPos, pScrollBar);

    // force redraw to cover any mess that may be created
    Invalidate();
    UpdateWindow();
}