Hide series in chartlistbox
lazarus / 55-TAChart

----------------------------------------------------------------------
madepabloh · 2014-09-09 22:08

I have a chart showing some datetime vs value line series as well as
constantline series at selected dates. Everything works well, and the
series are shown in a chartlistbox.

However, i have three issues i would like to solve, although i don´t
imagine how to do it.

1) I would like to hide the constant series from the chartlist box,
but still show them in the chart.
I tried "legend.visible := true", but i see now that it affects to the
legend, not the chartlistbox. I don't know how to do it.

2) I would like to show/hide the constantline series in the chart (all
at the same time) by the use of a checkbox or a radiobutton or a
button. I suposse that first thing to do is to search for all the
series in the chart, discover which type of serie it is, and then,
activate or disactivate it. Something like this:
Code: [Select]procedure TMain.CheckBox5Change(Sender: TObject);
var
  ser: TConstantLine;
begin
  if CheckBox5.Checked = True then
    begin
      for i:= 0 to Charteng1.Series.Count-1 do
        begin
          if Charteng1.Series.Items[i] = ser then
ChartEng1.Series.Items[i].Active:= True;
        end;
    end
  else
    begin
      for i:= 0 to Charteng1.Series.Count-1 do
        begin
          if Charteng1.Series.Items[i] = ser then
ChartEng1.Series.Items[i].Active:= False;
        end;
    end;
end;
This code compiles, but evidently it is not correct (do nothing). How
could i see which kind of series is each one in the chart?

3) I would like to show only one line representing all the constat
series in the legend.
I suposse i should select one of the constantline serie, and to assing
"legend.Visible := True", meanwhile for the other constant series they
should be setted to false. How could i do this? I mean, the option i
have on mind is to search for the first constantline serie in the
chartlist box to made it visible in the legent and hide the other
constantlines in the legend. However, since in the first task i will
remove (hopefully) those series from the chartlistbox, i should search
directly in the chart... but then i am back to problem i have in the
task 2. How to search for the type of series is each serie in the
chart?

i appreciate any tip to help me to solve those issues. thanks!

----------------------------------------------------------------------
wp · 2014-09-09 22:26

(1) There's a special event for the ChartListbox that is fired when a
series is added: OnAddSeries. It has a "Skip" parameter which you can
set to false in order to skip the series:
Code: [Select]procedure TForm1.ChartListbox1AddSeries(ASender:
TChartListbox;
  ASeries: TCustomChartSeries; AItems: TChartLegendItems; var ASkip:
Boolean);
begin
  if ASeries is TConstantLine then ASkip := true;  // this hides all
constant line series from the listbox, or
  if ASeries.Index = 0 than ASkip := true;   // this hide the series
with index 0 from the listbox, etc.
end;

(2) No, this code does not work: the local variable "ser" is not
initialized. Instead of looking for series variables I'd look for the
class:
Code: [Select]procedure TMain.CheckBox5Change(Sender: TObject);
begin
  for i:= 0 to Charteng1.Series.Count-1 do
    if ChartEng1.Series[i] is TConstantLine then
ChartEng1.Seres[i].Active := Checkbox5.Checked;
end;

(3) To search for a given series "type" use the "is" operator along
with the class name:
Code: [Select]  if Chart1.Series[i] is TBarSeries then ...  // true
for all bar series
  if Chart1.Series[i] is TBasicPointSeries then ... // true for all
bar series, line series, area series since they inherit from
TBasicPointSeries

----------------------------------------------------------------------
madepabloh · 2014-09-09 22:33

You are perfect (as ever) @WP!!

I will study your code, not only to apply, but to learn with this.
Thanks so much. I really appreciate.
Thanks!