Area Graph Question

[mh]

When I'm graphing a single point, the area graph only shows a single dashed verticle line up the the value of the point.

Is there any way to change the display of the graph so it draws the single point from the bottom-left of the chart window to the point to the bottom-right of the chart window? This would then show a single point essentially as a pyramid. As it is, viewing a single data point sometimes confuses the customer because it looks like nothing was graphed.

Thanks

[Yeray]

Hello mh,

To plot an area series you should have, at least, two points to define a valid area to be plotted. Anyway, if you wish to achieve what you request you could use something like the AddValue method and OnGetPointerStyle event (to show the points you need) as in the example we implemented below.

Code: Select all

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Chart1: TChart;
    Series1: TAreaSeries;
    Button1: TButton;
    TeeCommander1: TTeeCommander;
    procedure FormCreate(Sender: TObject);
    function Series1GetPointerStyle(Sender: TChartSeries;
      ValueIndex: Integer): TSeriesPointerStyle;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
    OnePoint: boolean;
    procedure AddValue(y: double);
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.AddValue(y: double);
begin
     if Series1.Count = 0 then
     begin
          OnePoint:=true;
          Series1.Add(y-1);
          Series1.Add(y);
          Series1.Add(y-1);
     end
     else
         begin
           if OnePoint then
           begin
                Series1.Delete(0);
                Series1.Delete(Series1.Count-1);
                Series1.XValues.FillSequence;

                OnePoint:=false;
           end;

           Series1.Add(y);
         end;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  Series1.Clear;
  Series1.Pointer.Visible:=true;

  OnePoint:=false;
  AddValue(random);
end;

function TForm1.Series1GetPointerStyle(Sender: TChartSeries;
  ValueIndex: Integer): TSeriesPointerStyle;
begin
  if OnePoint then
  begin
    if (ValueIndex = 1) then
       result := psRectangle
    else
        result := psNothing;
  end
  else
    result := psRectangle;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
     AddValue(random);
end;

end.

[mh]

Thanks for the tip. However we are utilizing the graph inside of a Report Builder report, so we don't have programmatic access to it. I guess we'll have to adjust the data or select another report style.

Thanks again

[Narcís]

Hi mh,

If you don't have access to all those events and properties in Report Builder you could use an invisible TChart, export it to an image and then load the image into Report Builder. For more information on how to export TeeChart to images please read Tutorial 12 - Exporting and Importing Charts. You'll find the tutorials at TeeChart's program group.