色の指定は uses に UIConsts

procedure TCandleChartCreator.DrawCandle;
var
  tmpRectF: TRectF;
begin

  ChartBitmap.SetSize(Round(FWidth), Round(FHeight));

  tmpRectF.Left   := FWidth *0.05;
  tmpRectF.Right  := FWidth *0.95;
  tmpRectF.Top    := FHeight*0.05;
  tmpRectF.Bottom := FHeight*0.95;

  with ChartBitmap.Canvas do
  begin
    BeginScene;
    Stroke.Kind := TBrushKind.bkSolid;
    Stroke.Color :=  claLime;
    StrokeThickness := 4;
    DrawRect(tmpRectF, 20, 20, AllCorners, 1.0);
    EndScene
  end;

end;