Steema Central

Posted: **Mon Aug 18, 2014 2:01 pm**

Hi,

I am trying to add scroll to my chart, but not able to do it.
I added both horizontal and vertical scrollbars to scroll my chart.
But, I don't have any idea about, how to set Page Number, Small change, Large Change etc. (when Rect or animated zoom) in scrollbar OnChange event ?

I understood that number of page numbers setting based on the number of points?
Is it possible to set number of page numbers based on the number of scale units (instead of number of points)?

Thanks in advance,

Posted: **Tue Aug 19, 2014 9:45 am**

Hello,

skng wrote:I am trying to add scroll to my chart, but not able to do it.
I added both horizontal and vertical scrollbars to scroll my chart.
But, I don't have any idea about, how to set Page Number, Small change, Large Change etc. (when Rect or animated zoom) in scrollbar OnChange event ?

Small Change and Lagre Change are properties of the TScrollBar. Here you have the documentation Embardcadero gives for them:
http://docwiki.embarcadero.com/Librarie ... TScrollBar
http://docwiki.embarcadero.com/Librarie ... mallChange
http://docwiki.embarcadero.com/Librarie ... argeChange
http://docwiki.embarcadero.com/Librarie ... r.OnChange

The paging feature in TeeChart is explained with detail in "Tutorial 3 - Chart Paging". And there are a pair of examples under "All Features\Welcome !\Tools\Page Number" in the features demo.
Both the tutorials and the features demo are shipped with the binary installation.

skng wrote:I understood that number of page numbers setting based on the number of points?

The pages function is designed to be set knowing the number of point per page. Once you've set the number of points to show in a page, you can call PreviousPage/NextPage methods to move back/forward in the pages. Or you can jump to a desired page number setting the Current property.

skng wrote:Is it possible to set number of page numbers based on the number of scale units (instead of number of points)?

If you want to implement a custom navigation, you can just use the bottom axis SetMinMax function.
You just have to calculate the increment you want to set in your TScrollBar OnChange, and set the bottom axis in a similar way as in the example below:

Code: Select all

uses Series;

var incr: Double;

procedure TForm1.FormCreate(Sender: TObject);
var i: Integer;
begin
  with Chart1.AddSeries(TBarSeries) do
    for i:=0 to 8 do
      AddXY(i*i, 50+random*50);

  ScrollBar1.Max:=5;
  ScrollBar1.Min:=0;
  incr:=(Chart1[0].XValues.MaxValue-Chart1[0].XValues.MinValue)/(ScrollBar1.Max-ScrollBar1.Min+1);

  Chart1.Axes.Bottom.MinimumOffset:=20;
  Chart1.Axes.Bottom.MaximumOffset:=20;
  ScrollBar1Change(Self);
end;

procedure TForm1.ScrollBar1Change(Sender: TObject);
begin
  Chart1.Axes.Bottom.SetMinMax(ScrollBar1.Position*incr,
                               (ScrollBar1.Position+1)*incr);
end;

Posted: **Tue Aug 19, 2014 2:17 pm**

Thanks for your reply Yeray.

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