Showing size grip in CDialog?

Question

I have seen code which handles the drawing of this thing (DFCS_SCROLLSIZEGRIP), but surely there is a window style which I can apply to get it "for free". Right?

Answer 1

In lieu of a better answer, I will post the code I have that draws the size grip and handles the hit-testing. You also need to invalidate the appropriate area during OnSize in order to get it repainted.

BOOL CMyDialog::OnEraseBkgnd(CDC* pDC)
{
    if (CDialog::OnEraseBkgnd(pDC))
    {
        // draw size grip
        CRect r;
        GetClientRect(&r);
        int size = GetSystemMetrics(SM_CXVSCROLL);
        r.left = r.right - size;
        r.top = r.bottom - size;
        pDC->DrawFrameControl(&r, DFC_SCROLL, DFCS_SCROLLSIZEGRIP);
        return TRUE;
    }
    else
    {
        return FALSE;
    }
}

-

LRESULT CMyDialog::OnNcHitTest(CPoint point)
{
    // return HTBOTTOMRIGHT for sizegrip area
    CRect r;
    GetClientRect(&r);
    int size = GetSystemMetrics(SM_CXVSCROLL);
    r.left = r.right - size;
    r.top = r.bottom - size;
    ScreenToClient(&point);

    if (r.PtInRect(point))
    {
        return HTBOTTOMRIGHT;
    }
    else
        return CDialog::OnNcHitTest(point);
}

Source: http://www.tech-archive.net/Archive/Development/microsoft.public.win32.programmer.ui/2006-01/msg00103.html

Answer 2

I don't think there is a default style to get this functionality for free. You have to create a new child window with class name Scrollbar and control style SBS_SIZEGRIP

Answer 3

In addition to OnEraseBkgnd and OnNcHitTest mentioned by the above you will need to invalidate the grip area when the window sized, otherwise it will leave marks when enlarged:

void CMyDialog::OnSize(UINT nType, INT cx, INT cy)
{

    CRect  rc;
    int    iSize=GetSystemMetrics(SM_CXVSCROLL);

    GetClientRect(rc);
    InvalidateRect(CRect(rc.left-iSize, rc.bottom-iSize, rc.right, rc.bottom), FALSE);
    CDialog::OnSize(nType, cx, cy);
}