MFC: CCheckListBox items overlap - mfc

Question

In a dialog template I placed a ListBox, since checked list box is not shown in the visual layout options. I set it to owner-draw and set it up with DDX, changing the associated class variable from type CListBox to CCheckListBox - in other words the only changes I make from what the wizard does for me are set owner-draw, and chnage the member variable type.
in my dialog's OnInitDialog method I then test with:
m_List.AddString(_T("One"));
m_List.AddString(_T("Two"));
m_List.AddString(_T("Three"));
m_List.AddString(_T("Four"));
m_List.SetCheck(1,1);
When I run the list is there, with 4 items and one checked, with the right strings. But, the item heights are wrong. It seems like the height of the checkbox is used to determine the item height, leading to the text overlapping the item below.
Shouldn't the default behavior of the class be to figure this out, without me having to individually set each item's height?

Answer 1

From MSDN:
If your checklist box is a default
checklist box (a list of strings with
the default-sized checkboxes to the
left of each), you can use the default
CCheckListBox::DrawItem to draw the
checklist box. Otherwise, you must
override the CListBox::CompareItem
function and the
CCheckListBox::DrawItem and
CCheckListBox::MeasureItem functions.
Looks like you either need to call the default implementation or implement your own MesaureItem/DrawItem. That's probably why the items seem to overlap.

Answer 2

In a check box, string case the following may be sufficient to prevent overlap:
class CCheckListBoxEx : public CCheckListBox
{
public:
virtual void DrawItem(LPDRAWITEMSTRUCT lpDrawItemStruct)
{
// set item height once:
if ((GetStyle() & (LBS_OWNERDRAWFIXED | LBS_HASSTRINGS)) ==
(LBS_OWNERDRAWFIXED | LBS_HASSTRINGS) && m_cyText == 0)
{
SetItemHeight(0, CalcMinimumItemHeight() + 2);
}
// add some space between box and string:
lpDrawItemStruct->rcItem.left += 2;
CCheckListBox::DrawItem(lpDrawItemStruct);
}
};