Scrolling ScrollBox to "invisible" child control

[jamie]

ok attached is an example of problems with forms or controls with no scrollbars showing..

it also can make a control disappear at the top with no way to get it back.

These scrolling features should only work in the presents of an active scrollbar and only limited to a scrollbar range.

[zoltanleo]

These scrolling features should only work in the presents of an active scrollbar and only limited to a scrollbar range.

Code: Pascal  [Select][+][-]

1. procedure TForm1.Button1Click(Sender: TObject);
2.   function IsChildControl(aControl: TControl): Boolean;
3.   var
4.     FControl: TControl = nil;
5.   begin
6.     Result:= False;
7.     FControl:= aControl;
8.  
9.     while FControl.Parent <> nil do
10.     begin
11.       if FControl.Parent = Self then
12.       begin
13.         Result:= True;
14.         Break;
15.       end;
16.       FControl:= FControl.Parent;
17.     end;
18.   end;
19. begin
20.   if not IsChildControl(TControl(Sender)) then Exit;//Relevant for Scrollbox
21.   if not Self.AutoScroll then Exit;
22.   Self.scrollinview(Button2);
23. end;

?

[Michl]

These scrolling features should only work in the presents of an active scrollbar

OK this has nothing to do with the latest changes and was even possible before the changes.

So by default, it would be good to have a bugreport about it, so the reasons for a behaviour change can be found also in some years.

I understand, why a scrolling feature is usefull, with only visible ScrollBars. I added a check in revision 65085.

[Michl]

These scrolling features should only work in the presents of an active scrollbar and only limited to a scrollbar range.

Code: Pascal  [Select][+][-]

1. procedure TForm1.Button1Click(Sender: TObject);
2.   function IsChildControl(aControl: TControl): Boolean;
3.   var
4.     FControl: TControl = nil;
5.   begin
6.     Result:= False;
7.     FControl:= aControl;
8.  
9.     while FControl.Parent <> nil do
10.     begin
11.       if FControl.Parent = Self then
12.       begin
13.         Result:= True;
14.         Break;
15.       end;
16.       FControl:= FControl.Parent;
17.     end;
18.   end;
19. begin
20.   if not IsChildControl(TControl(Sender)) then Exit;//Relevant for Scrollbox
21.   if not Self.AutoScroll then Exit;
22.   Self.scrollinview(Button2);
23. end;

I forgot to add the check, if TScrollingWinControl is parent of control. Thank you for the hint. It is now added in latest revision.

[jamie]

That apparently fixed the issue, it no longer scrolls if there are no scrollbars visible.

On a unrelated bug I just found while testing this.

The IO has issues when selecting AutoScroll = true, shrink the form so the scrollbars come on, then set AutoScroll := false and expand the form, the scrollbars don't go away..

 I would expect the form to refresh with no scrollbars when autoScroll is set to false in the OI.

 I actually have to expand the form, toggle the AUtoScroll to correct it..

I guess I can report this as a separate bug.