DOCUMENT:Q281155 08-MAY-2002 [visualc] TITLE :PRB: HDN_XXX Notifications Incorrectly Generated for CListView PRODUCT :Microsoft C Compiler PROD/VER:: OPER/SYS: KEYWORDS:kbHeaderCtrl kbListView kbMFC kbDSupport kbGrpDSMFCATLkbfaq ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - The Microsoft Foundation Classes (MFC) ------------------------------------------------------------------------------- SYMPTOMS ======== You use ClassWizard to add header control notification handlers such as HDN_ENDTRACK to a CListView, but the handlers do not get executed. This article provides a way to work around this problem. CAUSE ===== The header control is a child window of the CListView. The header control uses WM_NOTIFY messages to send notifications to its parent, the CListView. For your code to trap HDN_XXX notification codes therefore, you must use ON_NOTIFY handlers in the CListView class. However, the ClassWizard incorrectly inserts a ON_NOTIFY_REFLECT handler instead of a ON_NOTIFY handler. RESOLUTION ========== NOTE: You can use the following procedure for any HDN_XXX notification. This example uses HDN_ENDTRACK. 1. Use the ClassWizard to add a handler to HDN_ENDTRACK for the CListView-derived view. 2. In the CListView-derived class's message map, delete the following line: ON_NOTIFY_REFLECT(HDN_ENDTRACK, OnEndtrack) 3. Insert the following line just before the END_MESSAGE_MAP() macro: ON_NOTIFY(HDN_ENDTRACK, 0, OnEndtrack) // 0 is the control ID of the Header control The prototypes/handlers that are generated by the wizard would remain the same. That is, of the form: afx_msg void OnEndtrack(NMHDR* pNMHDR, LRESULT* pResult); and void CAppView::OnEndtrack(NMHDR* pNMHDR, LRESULT* pResult) { HD_NOTIFY *phdn = (HD_NOTIFY *) pNMHDR; // TODO: Add your control notification handler code here *pResult = 0; } respectively. MORE INFORMATION ================ Steps to Reproduce Behavior --------------------------- 1. Create an MFC AppWizard SDI EXE project named "App". Use the defaults. At the last step, change CAppView's base class to CListView. 2. Use ClassWizard to add a message handler under class CAppView for the message "=HDN_ENDTRACK". This will add the following handler to the message map: ON_NOTIFY_REFLECT(HDN_ENDTRACK, OnEndtrack) 3. Add the following lines to CAppView::OnInitialUpdate(): CListCtrl& listctrl = GetListCtrl(); listctrl.ModifyStyle( 0, LVS_REPORT ); listctrl.InsertColumn ( 0, "Col1", LVCFMT_LEFT, 100 ); listctrl.InsertColumn ( 1, "Col2", LVCFMT_LEFT, 100 ); 4. Build the project. 5. Set a break point in CAppView::OnEndtrack(). 6. Run the application under the debugger. 7. Select and drag to move one of the column dividers. Notice that the break point is not reached. REFERENCES ========== For additional information on the following topics, please see the MSDN Online Library Web page listed: CListView http://msdn.microsoft.com/library/devprods/vs6/visualc/vcmfc/_mfc_clistview.htm WM_NOTIFY http://msdn.microsoft.com/library/psdk/shellcc/commctls/Common/Messages/WM_NOTIFY.htm ON_NOTIFY http://msdn.microsoft.com/library/devprods/vs6/visualc/vcmfc/_mfcnotes_tn061.htm TN061: ON_NOTIFY and WM_NOTIFY Messages http://msdn.microsoft.com/library/devprods/vs6/visualc/vcmfc/_mfcnotes_tn061.htm Header Control Reference http://msdn.microsoft.com/library/psdk/shellcc/commctls/Header/header_Header.htm Platform SDK Documentation, Header Controls http://msdn.microsoft.com/library/psdk/shellcc/CommCtls/Header/Header.htm (c) Microsoft Corporation 2000, All Rights Reserved. Contributions by S. Ganesh, Microsoft Corporation. Additional query words: HDN_BEGINDRAG HDN_BEGINTRACK HDN_DIVIDERDBLCLICK HDN_ENDDRAG HDN_ENDTRACK HDN_FILTERBTNCLICK HDN_FILTERCHANGE HDN_GETDISPINFO HDN_ITEMCHANGED HDN_ITEMCHANGING HDN_ITEMCLICK HDN_ITEMDBLCLICK HDN_TRACK ====================================================================== Keywords : kbHeaderCtrl kbListView kbMFC kbDSupport kbGrpDSMFCATL kbfaq Technology : kbAudDeveloper kbMFC Version : : Issue type : kbprb ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 2002.