Steema Central

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uses series;

procedure TForm1.FormCreate(Sender: TObject);
begin
  Chart1.Legend.Alignment:=laBottom;

  with Chart1.AddSeries(TPointSeries) do
  begin
    FillSampleValues();
    Title:='short string';
  end;

  with Chart1.AddSeries(TPointSeries) do
  begin
    FillSampleValues();
    Title:='very very very long string';
  end;
end;

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{ Note: My chart has one series, but users have the option to set the color for a range of values.         }
{ The legend is customized to display the range of each selection and not the series name or series value.  }
unit LegendTextAlignment_48352;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, Series, TeEngine, ExtCtrls, TeeProcs, Chart;

type
  { TScatterPlotObjectColor }
  TScatterPlotObjectColor = class
  private
    FColor: LongInt;
  public
    property Color: LongInt read FColor write FColor;
    constructor Create(const AColor : LongInt);
  end;

  TForm2 = class(TForm)
    Chart1: TChart;
    procedure FormCreate(Sender: TObject);
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
  private
    { Private declarations }
    FLegendList : TStringList;
    FLegendStartIndex, FCurrentLegendTextIndex, FCurrentLegendImageIndex : Integer;
    FDebugStr : String;
  public
    { Public declarations }
    procedure BeforeDrawChart(Sender: TObject);
    procedure AfterDraw(Sender: TObject);
    procedure LegendDraw(Sender: TObject; Series: TChartSeries; ValueIndex: Integer; R: TRect);
    procedure SetLegendText(Sender: TCustomAxisPanel; LegendStyle: TLegendStyle; Index: Integer; var LegendText: String);
  end;

const
  OWNS_OBJECTS_FLAG : Boolean = True;
var
  Form2: TForm2;

implementation

{$R *.dfm}
{ *******************TScatterPlotObjectColor Class*********************** }
constructor TScatterPlotObjectColor.Create(const AColor : LongInt);
begin
  FColor := AColor;
end;

{ **************************TForm2 Class********************************** }
procedure TForm2.FormCreate(Sender: TObject);
begin
  { Override events to customize legend. }
  Chart1.Legend.Alignment:=laBottom;
  Chart1.Legend.LegendStyle := lsValues;
  Chart1.OnBeforeDrawChart := BeforeDrawChart;
  Chart1.OnGetLegendText := SetLegendText;
  Chart1.Legend.Symbol.OnDraw := LegendDraw;
  Chart1.OnAfterDraw := AfterDraw;
  { Set up items needed for customization. }
  FLegendList := TStringList.Create(OWNS_OBJECTS_FLAG);
  FLegendList.AddObject('SHORT_RANGE', TScatterPlotObjectColor.Create(clRed));
  FLegendList.AddObject('VERYVERY_LONGRANGE', TScatterPlotObjectColor.Create(clGreen));
  FLegendStartIndex := 0;
  FCurrentLegendTextIndex := 0;
  FCurrentLegendImageIndex := 0;
  { Add the series. }
  with Chart1.AddSeries(TPointSeries) do
  begin
    FillSampleValues();
    Title:='title';    // This does not matter in our code, as the title is only displayed in the mouseover, and not in the legend.
  end;
end;

procedure TForm2.FormClose(Sender: TObject; var Action: TCloseAction);
begin
  if Assigned(FLegendList) then FreeAndNil(FLegendList);
  Chart1.OnBeforeDrawChart := nil;
  Chart1.OnGetLegendText := nil;
  Chart1.OnAfterDraw := nil;
  Chart1.Legend.Symbol.OnDraw := nil;
  Chart1.Legend.FirstValue := 0;
end;

{ BeforeDrawChart overrides the TCustomChart OnDrawChart event to set the number of points to display in the legend - we *do not* want a legend item for every point! }
procedure TForm2.BeforeDrawChart(Sender: TObject);
begin
  try
    if Assigned(FLegendList) then begin
      TChart(Sender).Legend.FirstValue := TChart(Sender).Series[0].YValues.Count - FLegendList.Count;
      TChart(Sender).Legend.Symbol.Position := spLeft;
      TChart(Sender).Legend.Symbol.Width := 5;
      FLegendStartIndex := TChart(Sender).Legend.FirstValue;
    end;
  except
    on E : Exception do begin
      FDebugStr := 'TForm2.BeforeDrawChart: Exception caught - ' + E.Message;
      //DebugValue(DebugStr);
    end;
  end;
end;

{ SetLegendText overrides the OnGetLegendText event to allow customization of legend item text. }
procedure TForm2.SetLegendText(Sender: TCustomAxisPanel; LegendStyle: TLegendStyle; Index: Integer; var LegendText: String);{ HPDO-272 }
begin
  try
    LegendText := FLegendList[FCurrentLegendTextIndex];
    Inc(FCurrentLegendTextIndex);
  except
    on E : Exception do begin
      FDebugStr :=  'TScatterPlotDef.SetLegendText: Exception caught - ' + E.Message;
      //DebugValue(DebugStr);
    end;
  end;
end;

{ LegendDraw overrides the OnDraw event to allow customization of the legend symbol. }
procedure TForm2.LegendDraw(Sender: TObject; Series: TChartSeries; ValueIndex: Integer; R: TRect);
var
  ColorToPaint: LongInt;
begin
  try
    with TLegendSymbol(Sender) do begin
      ColorToPaint := TScatterPlotObjectColor(FLegendList.Objects[FCurrentLegendImageIndex]).Color;
      Chart1.Canvas.Brush.Color := ColorToPaint;
      Chart1.Canvas.Pen.Color := clBlack;
      Chart1.Canvas.Rectangle(R);
    end;
    Inc(FCurrentLegendImageIndex);
  except
    on E : Exception do begin
      FDebugStr :=  'TScatterPlotDef.LegendDraw: Exception caught - ' + E.Message;
      //DebugValue(DebugStr);
    end;
  end;
end;

{ AfterDraw overrides the TCustomChart OnAfterDraw event to reset all of the events and legend settings to their defaults prior to drawing other charts. }
procedure TForm2.AfterDraw(Sender: TObject);
begin
  Chart1.Legend.FirstValue := 0;
  Chart1.Legend.LegendStyle := lsAuto;
  FCurrentLegendTextIndex := 0;
  FCurrentLegendImageIndex := 0;
end;

end.

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Chart1.Legend.TextStyle:=ltsPlain;