CListBox::CompareItem

Статья
10/16/2008

Called by the framework to determine the relative position of a new item in a sorted owner-draw list box.

virtual int CompareItem(
   LPCOMPAREITEMSTRUCT lpCompareItemStruct 
);

Параметры

lpCompareItemStruct
A long pointer to a COMPAREITEMSTRUCT structure.

Возвращаемое значение

Indicates the relative position of the two items described in the COMPAREITEMSTRUCT structure. It may be any of the following values:

Value	Meaning
–1	Item 1 sorts before item 2.
0	Item 1 and item 2 sort the same.
1	Item 1 sorts after item 2.

See CWnd::OnCompareItem for a description of the COMPAREITEMSTRUCT structure.

Заметки

By default, this member function does nothing. If you create an owner-draw list box with the LBS_SORT style, you must override this member function to assist the framework in sorting new items added to the list box.

Пример

// CMyODListBox is my owner-drawn list box derived from CListBox. This 
// example compares two items using _tcscmp to sort items in reverse 
// alphabetical order. The list box control was created with the 
// following code:
//   m_myODListBox.Create(
//      WS_CHILD|WS_VISIBLE|WS_BORDER|WS_HSCROLL|WS_VSCROLL|
//      LBS_SORT|LBS_MULTIPLESEL|LBS_OWNERDRAWVARIABLE|LBS_WANTKEYBOARDINPUT,
//      CRect(10,250,200,450), pParentWnd, IDC_MYODLISTBOX);
//
int CMyODListBox::CompareItem(LPCOMPAREITEMSTRUCT lpCompareItemStruct)
{
   ASSERT(lpCompareItemStruct->CtlType == ODT_LISTBOX);
   LPCTSTR lpszText1 = (LPCTSTR) lpCompareItemStruct->itemData1;
   ASSERT(lpszText1 != NULL);
   LPCTSTR lpszText2 = (LPCTSTR) lpCompareItemStruct->itemData2;
   ASSERT(lpszText2 != NULL);

   return _tcscmp(lpszText2, lpszText1);
}