Codejock Developer Community : CXTListBase::AddColumn -- ItemCount = 0? http://forum.codejock.com/ Copyright (c) 2006-2013 Web Wiz Forums - All Rights Reserved. Thu, 11 Jun 2026 17:24:14 +0000 Thu, 29 May 2008 14:21:37 +0000 http://blogs.law.harvard.edu/tech/rss Web Wiz Forums 12.04 360 forum.codejock.com/RSS_post_feed.asp?TID=10689 <![CDATA[Codejock Developer Community]]> http://forum.codejock.com/forum_images/codejock-logo.gif http://forum.codejock.com/ <![CDATA[CXTListBase::AddColumn -- ItemCount = 0? : Or, perhaps -- using the default...]]> http://forum.codejock.com/forum_posts.asp?TID=10689&PID=35985&title=cxtlistbaseaddcolumn-itemcount-0#35985 Author: scruzer
Subject: 10689
Posted: 29 May 2008 at 2:21pm

Or, perhaps -- using the default parameter leads to the bug in the code?
 
virtual int AddColumn(
    LPCTSTR lpszColHeading,
    int nWidth = -1,
    int nFormat = LVCFMT_LEFT
);
 
again, looking at this code.  If you call this function the first time, with nWidth as the default parameter (-1)...  The call to GetItem will request item "-1". 
 
int CXTListBase::AddColumn(LPCTSTR lpszColHeading, int nWidth/*= -1*/, int nFormat/*= LVCFMT_LEFT*/)
{
  // if we are not in report mode return error.
   if ((GetWindowLong(m_pListCtrl->m_hWnd, GWL_STYLE) & LVS_TYPEMASK) != LVS_REPORT)
      return -1;
   // get a pointer to the header control, if NULL return error.
   CHeaderCtrl* pHeaderCtrl = _xtGetHeaderCtrl();
   if (pHeaderCtrl == NULL)
      return -1;
   int iIndex = pHeaderCtrl->GetItemCount();   // could be 0!
   if (nWidth == -1 && iIndex >= 0 )
   {
      // Get the column width of the previous column from header control
      HD_ITEM hd_item;
      hd_item.mask = HDI_WIDTH; //indicate that we want the width
      pHeaderCtrl->GetItem(iIndex - 1, &hd_item);
      nWidth = hd_item.cxy;
   }
   return m_pListCtrl->InsertColumn(iIndex, lpszColHeading, nFormat, nWidth, iIndex);
}
 
 My fix, "don't use the default parameter". 
]]> Thu, 29 May 2008 14:21:37 +0000 http://forum.codejock.com/forum_posts.asp?TID=10689&PID=35985&title=cxtlistbaseaddcolumn-itemcount-0#35985 <![CDATA[CXTListBase::AddColumn -- ItemCount = 0? : Perhaps because you asked it to...]]> http://forum.codejock.com/forum_posts.asp?TID=10689&PID=35434&title=cxtlistbaseaddcolumn-itemcount-0#35434 Author: Smucker
Subject: 10689
Posted: 19 May 2008 at 6:11pm

Perhaps because you asked it to get item iIndex - 1.

As good practice, you may also want to zero any structure you pass to APIs. (I don't think it matters for the header control):

  HD_ITEM hd_item = {0};


]]> Mon, 19 May 2008 18:11:42 +0000 http://forum.codejock.com/forum_posts.asp?TID=10689&PID=35434&title=cxtlistbaseaddcolumn-itemcount-0#35434 <![CDATA[CXTListBase::AddColumn -- ItemCount = 0? : From toolkit v11 -- In AddColumn,...]]> http://forum.codejock.com/forum_posts.asp?TID=10689&PID=35426&title=cxtlistbaseaddcolumn-itemcount-0#35426 Author: scruzer
Subject: 10689
Posted: 19 May 2008 at 2:42pm

From toolkit v11 -- In AddColumn, this code:
 
 int iIndex = pHeaderCtrl->GetItemCount();
 if (nWidth == -1 && iIndex >= 0 )
 {
  // Get the column width of the previous column from header control
  HD_ITEM hd_item;
  hd_item.mask = HDI_WIDTH;               //indicate that we want the width
  pHeaderCtrl->GetItem(iIndex - 1, &hd_item);
  nWidth = hd_item.cxy;
 }
doesn't get a valid hd_item when iIndex = 0!
 
 
 
 
]]> Mon, 19 May 2008 14:42:10 +0000 http://forum.codejock.com/forum_posts.asp?TID=10689&PID=35426&title=cxtlistbaseaddcolumn-itemcount-0#35426