TAChart Runtime FAQ

This wiki is trying to answer frequently asked questions related to usage of TAChart at runtime

Series

How to add a series at runtime?

Just create the series, set its properties and call the chart method AddSeries

uses
  TATypes, TASeries;

function AddLineSeries(AChart: TChart; ATitle: String): TChartSeries;
begin
  Result := TLineSeries.Create(AChart.Owner);
  with TLineSeries(Result) do
  begin
    // Series title for the legend
    SeriesTitle := ATitle;
    // Show data point markers (red fill color, black border)
    ShowPoints := true;  
    Pointer.Brush.Color := clRed;
    Pointer.Pen.Color := clBlack;
    Pointer.Style := psCircle;
    // Show red line segments connecting the data points
    ShowLines := true;   
    LinePen.Style := psSolid;
    SeriesColor := clRed;
  end;
  // Add new series to the chart
  AChart.AddSeries(Result);
end;

How to iterate through the series of a chart?

The series are accessible via the array-like property Series of the chart. Note that this returns only the most fundamental series type, TBasicChartSeries, and a type-cast may be necessage before being able to access the series properties.

The following example re-colors all line series in red:

uses
  TASeries;
var 
  i: Integer;
begin
  for i := 0 to AChart.SeriesCount-1 do
    if AChart.Series[i] is TLineSeries then
      TLineSeries(AChart.Series[i]).SeriesColor := clRed;
end;

If you prefer the more modern iterators you can use the syntax

uses
  TASeries, TAEnumerators;
var
  ser: TCustomSeries;
begin
  for ser in CustomSeries(AChart) do
    TLineSeries(ser).Series.Color := clRed;
end;

How to delete/hide a series at runtime?

• If you don't need the series any more just destroy it: series.Free.
• If you want to keept it for other usage, for example to insert it into another chart, call Chart.DeleteSeries(series).
• If you want to hide it, but keep it in the chart, set the property Active of the series to false.

Miscellaneous

What can I do to avoid compiler error "Identifier not found 'TDoublePoint'"?

TDoublePoint is declared in unit TAChartUtils, add it to the uses clause of the unit. It also contains the declaration of

• TDoubleRect which is needed for chart extents.

Other declarations, often not found when working with run-time code, are

• TSeriesMarksStyle for the Style of axis and series Marks --> in unit TAChartUtils
• TSeriesPointerStyle for the series pointer styles, e.g. psCircle, psRectangle --> in unit TATypes
• geometrical functions (creation of TDoublePoint and TDoubleRect, overloaded operators for TPoint and TDoublePoints) are in unit TAGeometry