TAChart: Dynamic function series?
lazarus / 55-TAChart

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ironphil · 2011-09-15 11:41

It is possible to create function series at runtime? I want to
modelize peaks with gaussians but the number of peaks can change.
Right now I use line series that I create at runtime and store in a
dynamic array. It works well but I end up with polylines instead of
function series.

I understand how function series work but if I create them at runtime,
how do I declare the function to calculate Y values from X values? The
series will use the same function (gaussian curve), only the
parameters will change (centre, width, height) so I need a way to
provide different parameters to the calculate function.

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Ask · 2011-09-15 13:41

Code: [Select]fs := TFuncSeries.Create(Chart1);
fs.OnCalculate := @MyFunc;
Chart1.AddSeries(fs);

where MyFunc is your function.
It is of course free to use any variables you need.

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ironphil · 2011-09-15 15:05

Thank you, that's exactly what I needed.

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1660 · 2013-11-05 18:48

Hi,

Can someone pls give an example of "@Myfunc" =)

Quote from: Ask on September 15, 2011, 03:41:00 pmCode: [Select]fs :=
TFuncSeries.Create(Chart1);
fs.OnCalculate := @MyFunc;
Chart1.AddSeries(fs);

where MyFunc is your function.
It is of course free to use any variables you need.

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wp · 2013-11-05 19:47

Suppose you want to plot the sine function. Then you implement this
procedure as a method of any object, typically the form on which the
chart resides:

Code: [Select]procedure TForm1.MyFunc(const AX: Double; out AY:
Double);
begin
  AY := sin(AX);
end;

In addition you may have a look at the tutorial
http://wiki.lazarus.freepascal.org/TAChart_Tutorial:_Function_Series.

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1660 · 2013-11-06 08:16

Sry, but i really dont get it 

Code: [Select]implementation

{$R *.lfm}
{ TForm1 }
     
procedure TForm1.Button1Click(Sender: TObject);
var
  fs: Tfuncseries;
begin
  fs := TFuncseries.Create(Chart1);
  fs.OnCalculate := ???
  Chart1.Addseries(fs);
end;

procedure TForm1.MyFunc(const AX: double; out AY: double);
begin
  AY := sin(AX);
end; 


I already know this tutorial, but it doesnt solve my problem.

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wp · 2013-11-06 08:22

You have to assign the address of the user-provided method "MyFunc" to
the OnCalculate handler of the series, just as in a few postings
above:

Code: [Select]  fs.OnCalculate := @MyFunc;

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1660 · 2013-11-06 08:52

Ah, thank you =)