TDoublePoint in Chart

[svdg]

Maybe I'm not right here with my question and maybe it's a stupied question.
I want to get the x,y position under the mouse cursor in an xy chart. I find several solutions on this board, but they nearly always fall back on introducing a variable type TDoublePoint.
If I do this, I get the error : Identifier not found "TDoublePoint".
I'm using Lazarus 1.6 under Windows 10 and Linux and get the same error.
Did I forget something?
Any help would be appreciated.

[howardpc]

You don't say which XY chart component you are using.
If it does not provide an OnMouseMove event, then you can use some adaptation of this:

Code: Pascal  [Select][+][-]

1. uses ...LCLIntf, ...;
2.  
3. ...
4. var
5.   pt: TPoint;
6. begin
7.   if GetCursorPos(pt) then begin
8.     pt:=ScreenToClient(pt);
9.     WriteLn('mouseX=',pt.x,', mouseY=',pt.y); // or use pt.x, pt.y to suit your need
10.   end;
11. end;

The raw pt value is a screen coordinate, so for most uses needs to be transformed into coordinates appropriate to your form or control.

[wp]

TDoublePoint is declared in TAChartUtils - this is the first place to look for declarations not found. Other often-seeked units are TACustomSeries, TACustomSource and TAGeometry.

"Secret" hint: Click on these words in the uses clause with the CTRL key down to open these units in the source editor - now you can browse and see which treasures they contain (works, of course, throughout any source file).

[svdg]

Thanks a lot!