[Qt-interest] Gestures

[Carl Snellman]

Hey,

sorry for repost, but I'm now blocked with the basic gesture
recognizer not working. If there is anyone out there having any
suggestions, I would be more than happy to hear...

Thanks,
Carl

---------- Forwarded message ----------
From: Carl Snellman <carl.snellman at gmail.com>
Date: Fri, Aug 6, 2010 at 3:10 PM
Subject: Re: [Qt-interest] Gestures
To: qt-interest at trolltech.com


Hey Denis and others,

(apologies for bringing such old thread back alive; I've been working
on other stuff, and now got back to this)

I tried to implement my own gesture recognizer and bumped to a problem
right away.
I implemented the following recognizer:
>>>>>>>>>>>>>>>>>>>>>.
class MyTapGesture : public QTapGesture {
};

class MyGestureRecognizer : public QGestureRecognizer {
public:
   virtual QGesture *create ( QObject * target ) {
       qDebug() << "MyGestureRecognizer::create";
       return new MyTapGesture;
   }
   virtual void reset ( QGesture * gesture ) {
       qDebug() << "MyGestureRecognizer::reset";
   }

   virtual Result recognize(QGesture * gesture, QObject * watched,
QEvent * event) {
       qDebug() << "MyGestureRecognizer::recognize";
       return QGestureRecognizer::Ignore;
   }
};
<<<<<<<<<<<<<<<<<<<<<<<<<<<

then I registered the recognizer:

Qt::GestureType type = QGestureRecognizer::registerRecognizer(new
MyGestureRecognizer);
qDebug() << "Type:" << type;


The problem is that MyGestureRecognizer::recognize(..) never gets called!
I tried the app on Lenovo Ideapad S10-T3, and the imagegestures app
works fine otherwise, I get pan and pinch gestures.

The MyGestureRecognizer::create(..) gets called once. I also disabled
grabbing all other gestures:
>>>>>>>>>>>
//! [enable gestures]
//    grabGesture(Qt::PanGesture);
//    grabGesture(Qt::PinchGesture);
//    grabGesture(Qt::SwipeGesture);
   grabGesture(Qt::CustomGesture);
//! [enable gestures]
<<<<<<<<<<<<<
No love, whatever I do. This all in the "imagestures" example app. The
whole project is avaiable at
http://www.4shared.com/file/NEetzicb/imagegestures.html


On Mon, Jun 7, 2010 at 3:20 AM, Denis Dzyubenko <shadone at gmail.com> wrote:
> single-touch device and touch are only sent as mouse events. Gestures
> that come with Qt are touch-based, implemented using QTouchEvents, so
> they wont work out of the box there.

What I've understood is the MyGestureRecognizer should get a chance to
evaluate every input event, to recognize gestures from stream of
events. What is unclear to me is that what events are being passed to
gesture recognizers? QTouchEvents where mentioned above. Are mouse
events also passed to recognizers?
If not, it will be impossible to use gestures on say X11 systems, that
apparently provide only mouse events, and IMO this makes gestures
pretty much useless. (devices providing touch events are not that
common yet). Also, I dont see why we would not be able to recognize
all gestures (other than QPinchGesture) from mouse events? Why it
hasn't been implemented that way now? Definitely would be usefull if
gestures would work from mouse events out-of-the-box, if developer
wants to use them.

Thanks,
Carl