Get onMouseMove Labels instead of Values

[guzial]

i have on event procedure to get value of y mouse poistion

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FormatFloat('# ###,##0',(Round(aChart.CustomAxes.Items[i].CalcPosPoint(Y)))

but i don't have idea how to get on the same event value of labels when axis.Labelstyle = talText

tahnks in advance for any help

[Narcís]

Hi guzial,

You can try doing something like this:

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procedure TForm1.Chart1MouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Integer);
var YVal: Double;
    Index: Integer;
begin
  YVal := Chart1.Axes.Left.CalcPosPoint(Y);
  Index := Series1.YValues.Locate(YVal);

  if Index <>-1 then
    Chart1.Title.Text[0]:=Series1.Labels[Index];
end;

Hope this helps!

[guzial]

it is possible to show text not using series but just mouse position and axis?

[Narcís]

Hi guzial,

You can use custom labels as shown in the All Features\Welcome!\Axes\Labels\Custom Labels example in the features demo. Which can be found at TeeChart's program group. An then obtain labels like Chart1.Axes.Left.Items[Index].Text. However, I can't think of a way to relate them to the mouse position at the moment.

[guzial]

ok so if i do

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Axis.Items.Add(0, 'AAA');
Axis.Items.Add(1, 'BBB');

and then i know only value for example 0 or 1 it is not possible to get text for this values ??

[Narcís]

Hi guzial,

You should be able to do something as in the code below. However I've found that Chart1.Axes.Left.Items.Value doesn't store the correct value and therefore this code snippet doesn't work. I've added this defect (TV52012517) to our bug list to be fixed for future releases.

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procedure TForm1.Chart1MouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Integer);
var YVal: Double;
    i: Integer;
begin
  YVal := Chart1.Axes.Left.CalcPosPoint(Y);

  for i:=0 to Chart1.Axes.Left.Items.Count - 1 do
  begin
    if Chart1.Axes.Left.Items[i].Value = YVal then
      Chart1.Title.Text[0]:=Chart1.Axes.Left.Items[i].Text;
  end;
end;

[Narcís]

Hi guzial,

As an update, one of my colleagues pointed me out that TV52012517 is not a bug. When comparing floating point values you should specify a tolerance. For example, this works fine:

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uses Math, Types;

procedure TForm1.FormCreate(Sender: TObject);
var i: Integer;
begin
 Chart1.Axes.Left.Items.Clear;

 for i:=-5 to 5 do
 begin
   Series1.Add(i);
   Chart1.Axes.Left.Items.Add(i, 'Point ' + IntToStr(i));
 end;
end;

procedure TForm1.Chart1MouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Integer);
var YVal: Double;
 i: Integer;
begin
 YVal := Chart1.Axes.Left.CalcPosPoint(Y);

 for i:=0 to Chart1.Axes.Left.Items.Count - 1 do
 begin
   if CompareValue(Chart1.Axes.Left.Items[i].Value,YVal,0.1)=EqualsValue then
    Chart1.Title.Text[0]:=Chart1.Axes.Left.Items[i].Text;
 end;
end;