[SOLVED] How to completely remove series from a chart?
lazarus / 55-TAChart

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madepabloh · 2014-09-23 22:12

Long time ago i asked about to reset the series of a chart:
http://forum.lazarus.freepascal.org/index.php?topic=14374.0

Now, i would like to know how could i completely remove/delete all the
series from a chart. Not only to delete the data from the series but
to destroy the series created on runtime.

I tried this code i located somewhere in internet (with small changes
to allow its compilation), without results:
Code: [Select]procedure TMain.DeleteSeries(AChart: TChart);
var
MySeries: TBasicChartSeries;
i: integer;
begin
  with AChart do
    while AChart.SeriesCount > 0 do
      for i := AChart.SeriesCount-1 downto 0 do
        begin
          MySeries := AChart.Series.Items[i];
          RemoveSeries(AChart.Series.Items[i]);
          MySeries.Free;
        end;
end;
Thanks!

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wp · 2014-09-23 22:43

Code: [Select]  Chart1.ClearSeries;

This also deletes the series data if they are stored in the built-in
listsource of the series. If you had put the data into a separate
chartsource you'll have to delete them separately.

But be warned: if you had created the series at designtime the
identifier "Chart1LineSeries1" still exists, but of course, accessing
it raises an exception because the series does no longer exist.

Except for the unnecessary "while" (or: with the "while", but using
always Items[0] without the "for"), what's wrong with your code? It
should work, according to my experience.

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madepabloh · 2014-09-23 22:56

I tried both
QuoteChar1t.Series.Clear;

Chart1.ClearSeries;

But it seems not work because i assigned tags, and names to each
series when they were created on runtime. After to clear the series,
if i try to plot the same data, it returns and error because the
series names already exist... what i interpret this is because the
series were not completely removed... am i right?

Edited:

Ok, it seems that what you say about the identifier could be the
problem.

When i create the serie in runtime, i assign a name to the new serie:
Code: [Select]ls.Name := 'S_'+ Table.Cells[i,3];
After to clear the data, if i load the same data to be plotted, the
error returned say:
QuoteDuplicate name: a component named "Vcc" already existsVcc is
thename of the first column in the stringgrid i try to plot...

This is why i assumed that it was caused because the serie was not
deleted, but you say that the serie is etleted although the component
name persist... How could i delete it to not to have conflict? Thanks!

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wp · 2014-09-23 23:25

Yes, I can confirm now that there is no exception... Strange!

Anyway, to convince you that the series is really removed I wrote two
short procedures, one adds a series, and the other one removes all
series. Both procedures ask the chart for the current series count,
and they also seek the form for series owned. Both methods return the
same number. In addition you can compile this with the heaptrace
option set - there is no memory leak when the program ends:

Code: [Select]procedure TForm1.Button1Click(Sender: TObject);  // Add
a series
var
  ser: TChartSeries;
  i, n: Integer;
begin
  ser := TLineSeries.Create(self);
  TLineSeries(ser).SeriesColor := rgb(random(256), random(256),
random(256));
  for i:=0 to 10 do ser.AddXY(i, random);
  Chart1.AddSeries(ser);

  n := 0;
  for i:=0 to ComponentCount-1 do begin
    if Components[i] is TChartSeries then inc(n);
  end;
  ShowMessage(
    Format('The chart reports %d series.'#13'The form owns %d
series.', [
    Chart1.SeriesCount, n]));
end;

procedure TForm1.Button2Click(Sender: TObject);  // remove all series
var
  i: Integer;
  n: Integer;
begin
  Chart1.ClearSeries;

  n := 0;
  for i:=0 to ComponentCount-1 do begin
    if Components[i] is TChartSeries then inc(n);
  end;
  ShowMessage(Format('The chart reports %d series.'#13'The form owns
%d series.', [
    Chart1.SeriesCount, n]));

end;

BTW, when creating series (or any other components) at runtime I
normally do not set their "Name" property to avoid that duplicate name
issue. For accessing these components, I use their variable name
instead (like "ser" in above example).

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madepabloh · 2014-09-23 23:33

@wp, of course i believe you!! I was only describing what i saw...
In fact, i edited my previous post to confirm your idea that the name
was the problem...

I edited the lines of my code were i setted the name to each serie...
and now everything works perfect...
So, SOLVED.

Anyway, your code is so interesting, and i will usein some way to
check forthe number of series in each plot. Thanks!!