Thank you so much John. I was socialized with Qt 4, and this explains exactly
the disconnect between my mental model and reality.
Surprisingly, none of my code broke because of that second new press in Qt5, so
I never noticed that.
Cheers
Robert
From: Interest <interest-boun...@qt-project.org> On Behalf Of John Weeks
Sent: Wednesday, 3 September 2025 19:37
To: interest@qt-project.org
Subject: Re: [Interest] Sequence of events in a double click
CAUTION: External email. Do not click on links or open attachments unless you
know the sender and that the content is safe.
There is a flag that alerts you to the fact that the second MousePressEvent is
the second of a double-click. Here is our code to handle it:
if (event->flags() & Qt::MouseEventCreatedDoubleClick) {
return;
}
And, yes, that was a change between Qt 4 and Qt 5 that caused us quite a bit of
grief.
-John Weeks
WaveMetrics, a division of Sutter Instrument, Inc.
On 9/3/2025 6:14 AM, Axel Spoerl via Interest wrote:
Servus Robert,
Just to clarify: Indeed, the behavior is intended.
I am already old ��
:wq
Axel
Confidential
________________________________
From: Interest
<interest-boun...@qt-project.org><mailto:interest-boun...@qt-project.org> on
behalf of Schimkowitsch Robert
<robert.schimkowit...@andritz.com><mailto:robert.schimkowit...@andritz.com>
Sent: Wednesday, 3 September 2025 14:26
To: interest@qt-project.org<mailto:interest@qt-project.org>
<interest@qt-project.org><mailto:interest@qt-project.org>
Subject: Re: [Interest] Sequence of events in a double click
Hi Axel,
thanks for that pointer. I can now follow how
QGuiApplicationPrivate::processMouseEvent() first receives the events, detects
that an event is a double click, then calls my filter with the original event,
and then calls my filter again with an extra double click event in case of a
double click. So I guess this is intended behavior.
That said, I use Qt since 2009, so either things have changed sometimes between
then and 2017, or the behavior was subtly different when only observing events
on the widget or graphics view level. With an event filter, I am of course much
lower-level.
I’m getting old...
Kind regards
Robert
From: Interest
<interest-boun...@qt-project.org><mailto:interest-boun...@qt-project.org> On
Behalf Of Axel Spoerl via Interest
Sent: Wednesday, 3 September 2025 13:42
To: interest@qt-project.org<mailto:interest@qt-project.org>
Subject: Re: [Interest] Sequence of events in a double click
CAUTION: External email. Do not click on links or open attachments unless you
know the sender and that the content is safe.
Servus Robert,
QGuiApplication::processMouseEvent() consumes the second mouse press event and
sends an additional QEvent::Type::MouseButtonDblClick if the time between two
presses is within the double click interval
(QGuiApplication::styleHints()->mouseDoubleClickInterval()).
That said, when the second press event is received, Qt doesn't know if it meets
the criteria for a double click.
The second press event has been sent for as long as I remember. That is,
according to git blame, at least since 2017 ;-)
Cheers
Axel
Confidential
________________________________
From: Interest
<interest-boun...@qt-project.org<mailto:interest-boun...@qt-project.org>> on
behalf of Schimkowitsch Robert
<robert.schimkowit...@andritz.com<mailto:robert.schimkowit...@andritz.com>>
Sent: Wednesday, 3 September 2025 11:43
To: interest@qt-project.org<mailto:interest@qt-project.org>
<interest@qt-project.org<mailto:interest@qt-project.org>>
Subject: Re: [Interest] Sequence of events in a double click
A small correction: “ButtonDoubleRelease” does not exist. It should read
“ButtonRelease”
From: Interest
<interest-boun...@qt-project.org<mailto:interest-boun...@qt-project.org>> On
Behalf Of Schimkowitsch Robert
Sent: Wednesday, 3 September 2025 11:21
To: interest@qt-project.org<mailto:interest@qt-project.org>
Subject: [Interest] Sequence of events in a double click
CAUTION: External email. Do not click on links or open attachments unless you
know the sender and that the content is safe.
Hi all,
when you perform a double click on a mouse button (=pressing and releasing the
mouse button in fast sequence twice), I have, over many years, always expected
this sequence:
ButtonPress
ButtonRelease
ButtonDoublePress
ButtonDoubleRelease
It is consistent with what I get when I trace the window events using Spy++ (on
Windows, for context) on a simple application (not my own, since Spy++ crashes
when encountering the hooks of a serious Qt application, and I currently don’t
have a good replacement tool).
However, in my Qt 6.8.2 application using a window event filter, I receive the
following sequence:
ButtonPress
ButtonRelease
ButtonPress
ButtonDoublePress
ButtonDoubleRelease
The extra press confuses me. Is this as it should be?
Kind regards
Robert
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