[Qt] viewportEvent of QAbstractScrollArea

[Paul Ishenin]

Den Jean wrote:

> I still think it is better to use eventfilter to be able to use 
> descendants aswell. But I released V1.52 with this request anyhow.
> http://users.pandora.be/Jan.Van.hijfte/qtforfpc/fpcqt4.html

Ok, how I should install eventFilter to viewPort? Yes, viewport can be 
any widget and I can try to do the same as this method do:

procedure TQtObject.AttachEvents;
var
   Method: TMethod;
begin
   FEventHook := QObject_hook_create(TheObject);
   TEventFilterMethod(Method) := @EventFilter;
   QObject_hook_hook_events(FEventHook, Method);
end;

But look at QAbstractScrollArea::setViewport

         d->viewport->installEventFilter(d->viewportFilter);

So after setViewPort call my eventFilter will be overriden by own qt 
eventFilter. So how should I install eventFilter to viewport?

The only way is (hack):
   1. call setViewPort
   2. install eventFilter after that

Is it right? I think no, since this way is not prefered by qt. They 
defined some rules:
"When inheriting QAbstractScrollArea, you need to do the following:
...
     * Handle events received by the viewport in viewportEvent() - 
notably resize events."

Lest play by their rules, or if we do hacks then we might have troubles 
with next version of qt.

If I am wrong in understanding qt or bindings please correct me. I dont 
know maybe way wich I see as hack is legal way.


Best regards,
Paul Ishenin.