TTChartOnGetLegendText

type TTChartOnGetLegendText = procedure(ASender: TObject; LegendStyle, ValueIndex: Integer; Var LegendText: WideString) of object;

Type Library
TeeChartx

Description
You can use this event to override the text strings that TChartLegend paints.

ILegend has two different modes (or LegendStyles):

lsSeries Legend contains Series Names or Titles.

lsValues Legend contains a Series values or labels.

If the LegendStyle is lsAuto, TChartLegend paints in lsSeries mode if more than one Active Series exists in the Chart.