TDragPointTool always favoures the "left" point

[Whookie]

Hi!
I'm using a TChart with one LineSeries and a TDragPointTool but grapping the series and moving the point (I just allow moving it in Y-direction) always uses the point left of the mouse-position (in the example image, if you grap the series one pixel to the left of the y:0-mark you begin to move the y:-1 mark!!).

I think it would be good to have an option to either restrain the drag-operation to the mark itself or center the sensitiv area over a point (eg.: -0.5 to 0.5 move the y:0-mark).

I'm also missing an option to restrict movement beyond some values (like the minima/maxima of the left axis in the example). Maybe an OnDragPointAllow(Sender, Index, Var Cancel: Boolean) - event could be implemented?

[Yeray]

Hello,

I'm using a TChart with one LineSeries and a TDragPointTool but grapping the series and moving the point (I just allow moving it in Y-direction) always uses the point left of the mouse-position (in the example image, if you grap the series one pixel to the left of the y:0-mark you begin to move the y:-1 mark!!).

I think it would be good to have an option to either restrain the drag-operation to the mark itself or center the sensitiv area over a point (eg.: -0.5 to 0.5 move the y:0-mark).

I've added it to the wish list to be further investigated. I think looking for what of the two valueindex of the clicked line segment is the nearest to the mouse click should work better:
http://bugs.teechart.net/show_bug.cgi?id=748
Feel free to add you mail to the CC list to be automatically notified when an update arrives.

I'm also missing an option to restrict movement beyond some values (like the minima/maxima of the left axis in the example). Maybe an OnDragPointAllow(Sender, Index, Var Cancel: Boolean) - event could be implemented?

There's a OnDragPoint event for the TDragPointTool you could use to restrict this. Ie:

Code: Select all

var tmpMin, tmpMax: Double;

procedure TForm1.FormCreate(Sender: TObject);
begin
  tmpMin:=Chart1[0].YValues.MinValue;
  tmpMax:=Chart1[0].YValues.MaxValue;
end;

procedure TForm1.ChartTool1DragPoint(Sender: TDragPointTool;
  Index: Integer);
begin
  if ((Index>-1) and (Chart1[0].YValue[Index]>=tmpMax)) then
    Chart1[0].YValue[Index]:=tmpMax;

  if ((Index>-1) and (Chart1[0].YValue[Index]<=tmpMin)) then
    Chart1[0].YValue[Index]:=tmpMin;
end;