COMPAREITEMSTRUCT Structure

The COMPAREITEMSTRUCT structure supplies the identifiers and application-supplied data for two items in a sorted, owner-drawn list box or combo box.

typedef struct tagCOMPAREITEMSTRUCT {
    UINT   CtlType;
    UINT   CtlID;
    HWND   hwndItem;
    UINT   itemID1;
    DWORD  itemData1;
    UINT   itemID2;
    DWORD  itemData2;
} COMPAREITEMSTRUCT;

Parameters

CtlType

ODT_LISTBOX (which specifies an owner-draw list box) or ODT_COMBOBOX (which specifies an owner-draw combo box).

CtlID

The control ID for the list box or combo box.

hwndItem

The window handle of the control.

itemID1

The index of the first item in the list box or combo box being compared.

itemData1

Application-supplied data for the first item being compared. This value was passed in the call that added the item to the combo or list box.

itemID2

Index of the second item in the list box or combo box being compared.

itemData2

Application-supplied data for the second item being compared. This value was passed in the call that added the item to the combo or list box.

Remarks

Whenever an application adds a new item to an owner-drawn list box or combo box created with the CBS_SORT or LBS_SORT style, Windows sends the owner a WM_COMPAREITEM message. The lParam parameter of the message contains a long pointer to a COMPAREITEMSTRUCT structure. Upon receiving the message, the owner compares the two items and returns a value indicating which item sorts before the other.

See Also

Structures, Styles, Callbacks, and Message Maps | CWnd::OnCompareItem