TTChartOnSeriesBeforeDrawValues

type TTChartOnSeriesBeforeDrawValues = procedure(ASender: TObject; SeriesIndex: Integer) of object;

Type Library
TeeChartx

Description
The TTChartOnSeriesBeforeDrawValues event is called just before the Series points will be painted.You can then paint on the Chart.Canvas your customized drawings.

WARNING:

Do not change Series properties that would force the Series to be repainted. This may cause recursion and endless repainting !