TAxisScrollTool event to correct scroll

[Technicon]

Hello

Is it possible to force TAxisScrollTool to obey axis settings like pTChartAxis->ExactDateTime = true; pTChartAxis->Increment = DateTimeStep[dtFifteenMinutes];
I would try to do this but I can't find any event in TAxisScrollTool that would be proper for such functionality.
Any help appreciated.

Best Regards,
Grzegorz

[Yeray]

Hello,

The TChart OnScroll event is fired when you drag the mouse over an axis (having a TAxisScrollTool).

[Technicon]

Hello
I try to correct axis min and max from OnAllowScroll but there is probably a bug in TAxisScrollTool because it doesn't consider values than was changed inside that event.
There is also small bug that TAxisScrollTool call OnAllowScroll event with "Axis" variable instead of "AAxis".

Code: Select all

      if Assigned(TCustomChart(ParentChart).OnAllowScroll) then
      begin
        tmpMin:=AAxis.Minimum+ADelta;
        tmpMax:=AAxis.Maximum+ADelta;
        TCustomChart(ParentChart).OnAllowScroll(Axis,tmpMin,tmpMax,tmp);
      end;

Best Regards,
Grzegorz

[Yeray]

Hello Grzegorz,

OnAllowScroll event was thought to give the option to cancel the scroll action "on the fly", not to change the axis scale. To change the axis scale you should use OnScroll event.

[Technicon]

Hello,

I try to use OnScroll but I need information which axis was scrolled. Can you tell me how to do this please?

Best Regards,
Grzegorz

[Yeray]

Hello Grzegorz,

The problem I see is that when OnScroll event is fired, several axes could have been scrolled. At OnAllowScroll you could add "Sender" into an array of TChartAxis and check that array at OnScroll event (and clear it).

[Technicon]

Hello

I've had similar idea but the bug mentioned above doesn't let me to do this.
TAxisScrollTool call OnAllowScroll event with "Axis" variable instead of "AAxis". That's why I get NULL if none axis is selected or pointer to axis chosen in TAxisScrollTool settings instead of axis that do the real scroll.
This problem is also linked to bug http://bugs.teechart.net/show_bug.cgi?id=1651
Is there any time frame for resolving bugs that I reported ?

Best Regards,
Grzegorz

[Yeray]

Hello Grzegorz,

I've had similar idea but the bug mentioned above doesn't let me to do this.
TAxisScrollTool call OnAllowScroll event with "Axis" variable instead of "AAxis". That's why I get NULL if none axis is selected or pointer to axis chosen in TAxisScrollTool settings instead of axis that do the real scroll.

I'm sorry. I applied the fix you suggested above before testing the OnAllowScroll event, and that's why it worked for me.
The next maintenance release will include this small modification.

In your case, you could play with the OnMouseDown/OnMouseUp events to determine whether the scroll started over an axis. Ie:

Code: Select all

var onAxis: TChartAxis;

procedure TForm1.Chart1MouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
var i: Integer;
begin
  onAxis:=nil;
  for i:=0 to Chart1.Axes.Count-1 do
      if Chart1.Axes.Items[i].Clicked(X,Y) then
      begin
        onAxis:=Chart1.Axes.Items[i];
        Exit;
      end;

end;

procedure TForm1.Chart1MouseUp(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  onAxis:=nil;
end;

procedure TForm1.Chart1Scroll(Sender: TObject);
begin
  if Assigned(onAxis) then
     // adjust min and max as you wish
end;

This problem is also linked to bug http://bugs.teechart.net/show_bug.cgi?id=1651

As you can see the ticket is "In progress". I have a fix in the works waiting for a second verification.

Is there any time frame for resolving bugs that I reported ?

I'm afraid we can't say when the tickets will be closed. See the Bug Fixing Policy