Rebuilds the items of the legend. Call this method to force the legend list box to update. Usually, you should never need to call this method because the legend ensures its items are updated before painting itself. In rare cases, however, you may want to force the legend to update itself immediately and not wait until painting itself.
The legend fills its Items property based on the values in the
Panel properties. The Objects of the Items: TStrings contains the associated RSChartPanel.TRSCustomChart or RSChartPanel.TRSChartValue object.