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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
);
Parameters
- lpCompareItemStruct
A long pointer to a COMPAREITEMSTRUCT structure.
Return Value
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.
Remarks
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.
Example
// 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);
}
Requirements
Header: afxwin.h