[Qt-interest] QGraphicsView with QGestureEvent

[Elias Capito]

Hi,

I am using Qt 4.6.0 on Windows 7 x64, who is installed on a Dell Latitude XT
with the last N-Trig driver.

Is not related with the topic, but if you can answer, it would be good.

I have a question about the gesture QSwipeGesture and QTapAndHoldGesture,
the first are sometimes detect when I do strange gesture with many fingers,
but I don't know how :D and the second is never detect, but the match in
Windows is detect.

Best regards
Elias

2009/12/8 Raymond de Vries <reedev at xs4all.nl>

> Hi,
>
> Ok, I can confirm this here too with your sample application as well as my
> own application. Fyi, I am using my own built
> qt-everywhere-opensource-src-4.6.0 on Windows 7, Visual Studio 9 2008. I'm
> sorry that I did not get your (by Denis) first remark to grab the getures
> with the *viewport*, I was doing it on the graphicsview directly (which
> resulted in the same asserion btw).
>
> Any hints or tips are welcome.
>
> best regards
> Raymond
>
>
>
> Elias Capito wrote:
>
>>
>> Thanks for your reply Denis.
>>
>> I have add the all gesture to the viewport with
>> viewport()->grabGesture(...) in QGraphicsView and to my item, but when I
>> debug my application any gesture are delivered to the items.
>>
>> I have tested with QGraphicsView and my own herited class of
>> QGraphicsView.
>>
>> I have the following error when I make a gesture on an item and after i
>> touch the viewport (not an item) : *ASSERT: "!isEmpty<>" ..
>>
>> *
>> I add the source code* *in attachement*.
>> *
>>
>> Best regards
>>
>> 2009/12/7 Raymond de Vries <reedev at xs4all.nl <mailto:reedev at xs4all.nl>>
>>
>>
>>    Hi Denis,
>>
>>    I was also following this thread and I tried the same, with
>>    QGraphicsWebView but even with your advice, I don't get the
>>    gesture events...
>>
>>    This is what you mean to do:
>>    MTCanvas : public QGraphicsView
>>    constructor
>>     viewport()->setAttribute(Qt::WA_AcceptTouchEvents);
>>     grabGesture(Qt::PanGesture);
>>     grabGesture(Qt::PinchGesture);
>>     grabGesture(Qt::SwipeGesture);
>>     etc
>>    MTCancas::event() does receive Gesture events
>>
>>    MTWebBrowser : public QGraphicsWebView
>>    constructor
>>     setAcceptTouchEvents(true);
>>     grabGesture(Qt::PanGesture);
>>     grabGesture(Qt::PinchGesture);
>>     grabGesture(Qt::SwipeGesture);
>>     etc
>>    MTWebBrowser::event(QEvent *event) does not receive Gesture events
>>
>>    Is this supposed to work?
>>
>>    Thanks a lot, best regards
>>    Raymond
>>
>>
>>
>>
>>
>>    Denis Dzyubenko wrote:
>>
>>        Hi Elias,
>>
>>        2009/12/3 Elias Capito <elias.capito at gmail.com
>>        <mailto:elias.capito at gmail.com>>:
>>
>>
>>            I want to do a multitouch application.
>>
>>            I have a problem with the QGestureEvent on a
>>            QGraphicsObject item . I use
>>            "grabGesture" on my item in constructor and i debug to see
>>            the input event.
>>
>>            When I run the application, the QGestureEvent never
>>            appear, but if I use
>>            QTouchEvent on item in place of QGestureEvent, with
>>            "setAcceptTouchEvent",
>>            in my debug I can see the touch event.
>>
>>            If I use QGestureEvent with a simple QWidget and I run it,
>>            I can see the
>>            gesture event, so i think it's correct.
>>
>>            It's the first time, that I use QGraphicsView, so I think
>>            i have miss
>>            something.
>>
>>            Anyone have an idea, why the QGestureEvent not appear on
>>            my item ?
>>
>>
>>        right now to get gesture events on a QGraphicsObject it should
>>        subscribe to a gesture _and_ the viewport of the graphicsview
>>        should
>>        also explicitly subscribe to the same gesture. Apparently it isn't
>>        documented right now, sorry about that. Anyway, I this will be
>>        improved in future versions of Qt so that you will not have to
>>        do that
>>        manually (thank god I forgot to document that, so we can
>>        change the
>>        behavior ;) )
>>
>>        However for now you need to make sure the viewport also
>>        subscribes to
>>        the same gesture type.
>>
>>
>>
>>
>>
>
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