Adding Labels to points.
lazarus / 55-TAChart

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chucky · 2013-05-31 05:21

The Tutorial at

http://wiki.freepascal.org/TAChart_Tutorial:_Chart_Tools

procedure TForm1.ChartToolset1DataPointClickTool1PointClick(
  ATool: TChartTool; APoint: TPoint);
var
  x, y: Double;
begin
  with ATool as TDatapointClickTool do
    if (Series <> nil) then
      with (Series as TLineSeries) do begin
        x := GetXValue(PointIndex);
        y := GetYValue(PointIndex);
        { --- next line removed --- }
//        Statusbar1.SimpleText := Format('%s: x = %f, y = %f',
[Title, x, y]);
        { --- next line added --- }
        ListSource.SetText(PointIndex, Format('x = %f'#13#10'y = %f',
[x,y]));
      end;
end

does not compile under 1.0.8

There is no ListSource.SetText(). Was this tutorial written with an
older version of the chart package or is this something added since
the release of 1.0.8?

Using the 1.0.8 release is their a way of setting the text of a point
after it has been added?

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wp · 2013-05-31 10:44

I tried to write the tutorials from the release version which was
about 1.0 at this time. When using new features there should be a hint
in the text.

In your case, obviously a later version, probably the trunk version,
was used because the SetText method of the ListSource is a recent
addition. However, the functionality has already been there even in
the older versions since this method is just a short-cut for writing
Code: [Select]  ListSource.Item[PointIndex]^.Text := 'some text';

[EDIT] You have to repaint the chart afterwards to show the changes
immediately.

I'll modify the tutorial such that it compiles under older Lazarus
versions (but proably not under 0.xx).

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chucky · 2013-06-02 04:30

Thanks!!

 ListSource.Item[PointIndex]^.Text := 'some text'

is what I needed.