Re: Detect changes in ClistCtrl control with checkbox

From:
"Tom Serface" <tom@nospam.camaswood.com>
Newsgroups:
microsoft.public.vc.mfc
Date:
Tue, 13 Jan 2009 13:49:49 -0800
Message-ID:
<277E5EB2-D9B5-4734-AE3E-206DD6AC4329@microsoft.com>
 ON_NOTIFY(NM_CLICK, IDC_LIST, &CSpanRestoreDlg::OnNMClickList)

// Check or uncheck item. If more than one item is selected then use the
one from the
// hit test to determine how we are setting the others (I.E., if it is off
we turn the other
// selected ones on).
void CMyDlg::OnNMClickList(NMHDR *pNMHDR, LRESULT *pResult)
{
     NMLISTVIEW* pNMListView = (NM_LISTVIEW*)pNMHDR;
     LVHITTESTINFO hitinfo;
        *pResult = 0;

    bool bChecked = false;

     //Copy click point
     hitinfo.pt = pNMListView->ptAction;

     //Make the hit test...
     int nItem = m_cList.HitTest(&hitinfo);

     if(hitinfo.flags != LVHT_ONITEMSTATEICON)
          return; // Didn't click on an icon

     if(m_cList.GetItemState(nItem,LVIS_SELECTED) != LVIS_SELECTED) {
          // They clicked on one that is not selected... just change it
         // ... do something here
        bChecked = m_cList.GetCheck(nItem);
        bChecked = !bChecked;
        m_cList.SetCheck(nItem,bChecked);
        *pResult = 1;
          return;
     }

      // Get the checked state from the one they clicked on, but change all
the ones that are selected
      UINT uSelectedCount = m_cList.GetSelectedCount();
      // Update all of the selected items.
      if (uSelectedCount > 0) {
           nItem = -1;
           m_cList.SetRedraw(false);
           for (UINT i=0;i < uSelectedCount;i++) {
               nItem = m_cList.GetNextItem(nItem, LVNI_SELECTED);
                m_cList.SetCheck(nItem,bChecked);
           }
           *pResult = 1;
           m_cList.Invalidate();
           m_cList.SetRedraw();
      }
}

Tom

"asoni12" <asoni12@discussions.microsoft.com> wrote in message
news:C3A5D065-15DA-46BB-9F45-B8208D73E2D0@microsoft.com...

"Ajay Kalra" wrote:

On Jan 13, 11:31 am, asoni12 <ason...@discussions.microsoft.com>
wrote:

I am using a CListCtrl with LVS_EX_CHECKBOXES extended style. How can I
detect that a previously checked item has been unchecked or a
previously
unchecked item has been checked. I know that LVN_ITEMCHANGED event is
triggered whenever its state gets changed but how to find if the item
has
been checked / unchecked and its previously state.
Any help is appreciated.


Take a look at ListView_GetCheckState:
http://msdn.microsoft.com/en-us/library/bb761250(VS.85).aspx
and LVN_ITEMCHANGING:
http://msdn.microsoft.com/en-us/library/bb774847(VS.85).aspx

--
Ajay


Hi Ajay,
Thanks for the quick reply.
We get a pointer to an NMLISTVIEW structure in case of both both
LVN_ITEMCHANGING and LVN_ITEMCHANGED event handlers but with this
structure
how can we make sure whether items???s checked/unchecked state has been
toggled or something else has changed?
I mean is there any bit in this structure member which is set/unset when
the
state gets toggled?

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