Self-drawing CListBox, LBS_OWNERDRAWFIXED and subclassing

28 May 2004 14:31

If you’ve got a LISTBOX (as opposed to a ListView) control in a dialog, and you’re using LBS_OWNERDRAWFIXED, you might be surprised to find that your MeasureItem function is never called.

This is because the original WM_MEASUREITEM message is sent before the subclassing is finished. It doesn’t, therefore, get reflected to your CListBox-derived class.

The solution?

One solution is to use LBS_OWNERDRAWVARIABLE, so that you get called for each item. You can always return the same value for each. Another solution is to use the SetItemHeight function to set the height.

The same limitations apply to COMBOBOX controls created with the CBS_OWNERDRAWFIXED style.

Or you could do something devious to hide this nastiness:

void COwnerDrawListBox::PreSubclassWindow()

    if (GetStyle() & LBS_OWNERDRAWFIXED)
        MEASUREITEMSTRUCT measureItem;

        // MeasureItem will probably ignore these,
        // but we'll fill them in anyway:
        measureItem.CtlID = GetDlgCtrlID();
        measureItem.CtlType = ODT_LISTBOX;
        measureItem.itemID = -1;
        measureItem.itemData = 0;

        // MeasureItem is supposed to fill these in,
        // but we'll put some defaults in there:
        measureItem.itemWidth = 0;
        measureItem.itemHeight = 0;


        // For LBS_OWNERDRAWFIXED, nIndex should be zero.
        SetItemHeight(0, measureItem.itemHeight);