Tracking TChart cursor

[Curt Carpenter]

A minimal example of how to track mouse cursor location on a TChart.

[wp]

Yes, this works.

An idea for an extension: When you use a TDataPointCrossHairTool rather than a TUserDefinedTool you can utilize the fact that the mouse is caught near the data points and you can read out the exact values of the data points:

Code: Pascal  [Select][+][-]

1. procedure TForm1.ChartToolset1DataPointCrosshairTool1Draw(
2.   ASender: TDataPointDrawTool);
3. var
4.   ser: TChartSeries;
5.   idx: Integer;
6. begin
7.   if ASender <> nil then
8.   begin
9.     if ASender.Series <> nil then
10.     begin
11.       ser := ASender.Series as TChartSeries;
12.       idx := ASender.PointIndex;
13.       Label3.Caption := 'Series "' + ser.Title + '": x = ' + ser.XValue[idx].ToString + ' y = ' + ser.YValue[idx].ToString;
14.       exit;
15.     end;
16.     Label3.Caption := '';
17.   end;
18. end;