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> on behalf of
Schimkowitsch Robert <robert.schimkowit...@andritz.com>
*Sent:* Wednesday, 3 September 2025 14:26
*To:* interest@qt-project.org <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> *On Behalf Of *Axel
Spoerl via Interest
*Sent:* Wednesday, 3 September 2025 13:42
*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.*
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> on behalf of
Schimkowitsch Robert <robert.schimkowit...@andritz.com>
*Sent:* Wednesday, 3 September 2025 11:43
*To:* interest@qt-project.org <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> *On Behalf Of
*Schimkowitsch Robert
*Sent:* Wednesday, 3 September 2025 11:21
*To:* 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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