[Qt-interest] QGestureRecognizer TouchBegin

[Sean T. Hayes]

Sorry for the slow reply. I have been having problems with my email account.

On Fri, Apr 22, 2011 at 6:03 AM, Wathek LOUED <wathek at gmail.com> wrote:

> So my problem is that I was guessing what if a new touch point is added ?
> It should call once again TouchBegin and then it'll change the list of my
> touchpoints saved the first time, won't it ?
>

No, I do not think that is the case. TouchBegin only occurs when the first
touch point is added.

In order to determine if there are new touch points, use the
QTouchEvent's touchPointStates()
<http://doc.qt.nokia.com/latest/qtouchevent.html#touchPointStates>method.

On Fri, Apr 22, 2011 at 6:03 AM, Wathek LOUED <wathek at gmail.com> wrote:

> Hi all,
>
> I got a question about QGestureRecognizer when trying to grab a gesture
> let's say a pan gesture the recognize function goes through 3 events :
> TouchBegin => Check the number of touch Point and intialize the QGesture
> and set the QGesture state to MayBeGesture only if there's one touch point
> TouchUpdate => Change the QGesture's state to TriggerGesture and updating
> the QGesture
> TouchEnd => Change the QGesture's state to FinishGesture
>
>
> so for the TouchBegin what I'm doing is get all the touchPoints and
> filtering that list so that I get only the touchPoints contained into the
> watched QObject. There are two cases :
>
> * the watched QObject is a QGraphicsObject in that case I use bool
> QGraphicsItem::contains(const QPointF &) method.
> * the watched QObject isn't a QGraphicsObject so it's certainly a
> QGraphicsView in that case I get the last appended touchPoint.
>
> with that I update the QGesture vars, and in my TouchUpdate I use the
> points saved earlier.
>
> So my problem is that I was guessing what if a new touch point is added ?
> It should call once again TouchBegin and then it'll change the list of my
> touchpoints saved the first time, won't it ?
>
> Thank you so much
>
> Sincerely
> Wathek
>
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