It's the same situation with Move and Resize events. In Qt 4, you could do this:
bool myclass::eventFilter(QObject * target, QEvent *event)
{
static bool moving = false;
case QEvent::move:
// In Qt 4, the move event comes synchronously, so we know that
only our call to QWidget::move
// can cause a reentrant call here.
if (moving)
return;
moving = true;
... call QWidget::move ....
moving = false;
}
But in Qt 5 the Move event is put on the queue and delivered asynchronously. So
now I have this sort of code:
class myclass
{
...
private:
bool moving;
QWidget * movedWidget;
};
bool myclass::eventFilter(QObject * target, QEvent *event)
{
somewidget = qobject_cast<QWidget *>(target);
case QEvent::move:
// in Qt 5, the call to QWidget::move doesn't cause a reentrant
call here, it triggers
// another move event later on. So we have to store away info
on this call to QWidget::move,
// and detect that move event later on when it looks like other
move events.
if (moving && somewidget == movedWidget)
{
moving = false;
movedWidget = NULL; // not at C++11 yet!
return false;
}
moving = true;
movedWidget = somewidget;
somewidget->move();
return <whatever>;
}
I put in a check on the widget that was moved out of paranoia that some other
move event could sneek in while I was waiting. In our case, we have the same
filter on multiple widgets.
Warning: I could have made some typo in the process of abstracting the method
from much more complex code...
-John Weeks
On Oct 31, 2014, at 7:35 AM, Yili Pan <pyl0...@gmail.com> wrote:
> Hi Bo:
>
> Thank you for the reply!
>
> I do not want to filter out all the WindowActivate or FocusIn event tough,
> only these are triggered by calling QWidget::show(). But because the events
> are processed asynchronously in Qt5, when I catch them in the eventfilter, I
> don't know whether they are originated from calling show() or they are
> spontaneous event caused by manual interaction. I also tried to filter out
> the event by telling whether they are spontaneous, but unfortunately no
> matter where they originate from, they are spontaneous (could this be a
> bug??). Any thoughts or suggestion :)
>
> Thank you!
>
> -Yili
>
> On Fri, Oct 31, 2014 at 4:01 AM, Bo Thorsen <b...@vikingsoft.eu> wrote:
> Den 30-10-2014 20:30, Yili Pan skrev:
> > Hi:
> >
> > We want to block the widget's WindowActivate and FocusIn event
> > triggered by calling its show() function, with Qt4, we used to do
> > that by setting flag before and after show() and filter out the event
> > in eventfilter based on the flag. But with Qt5, the events are
> > processed asynchronously, we cannot block the event in the same way
> > anymore.
> >
> > Any ideas how I can identify those events that are caused by calling
> > QWdiget::show() and filter them out?
>
> You can use an event filter for this. Take a look at the documentation
> for QObject::installEventFilter, it should be simple to follow.
>
> Bo.
>
> --
> Viking Software
> Qt and C++ developers for hire
> http://www.vikingsoft.eu
>
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-John
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