Problem creating a new custom gesture

Karen Zurutuza

I need to create a new custom gesture with QGestureRecognizer class, but I've a problem when I try to call my gesture class in a widget class.

QGestureRecognizer CGest = new GestKey;
Qt::GestureType CGestId = QGestureRecognizer::registerRecognizer(CGest);
grabGesture(CGestId);

The error says "cannot allocate an object of abstract type"
GestKey is a derived class from QGestureRecognizer.

I'm new programming in Qt Creator, so I've looking for help to create a new custom gesture.
thanks.

SGaist

Hi and welcome to devnet,

Did you reimplement properly the pure virtual recognize function ?

Karen Zurutuza

@SGaist Hi and thanks
I can resolved the problem, but now when i try to call my function in the gesture event I've a new problem :

bool Llamada::gestureEvent(QGestureEvent *event)
{
if(QGesture *key = event->gesture(Qt::CustomGesture))
KeyTriggered(GestKey *(key));
return true;
}

the error says: "expected primary-expression before '*' token".
So I can't enter to my function "KeyTriggered"

SGaist

Hi,

It's because you have there something that is more of a declaration of a pointer than any thing else;

What you want to do is to do a cast to a pointer.

Karen Zurutuza

Hi, so I think that my implementation of the class QGestureRecognizer it's wrong, because in the function:
Qt::GestureType gestureRecognizer::registerRecognizer(QGestureRecognizer *recognizer)
{
}
Don't create the register. Can you help me to implement the function?

SGaist

You don't reimplement registerRecognizer. It's a static function that you use to register your own recognizer.

See this

Karen Zurutuza

I used this cast:

bool call::gestureEvent(QGestureEvent *event)
{
if (QGesture *key = event->gesture(Qt::CustomGesture))
KeyTriggered(static_cast<QGestureRecognizer>(key));
return true;
}

but this happend:

error: invalid static_cast from type 'QGesture*' to type 'QGestureRecognizer*'
TeclaTriggered(static_cast<QGestureRecognizer*>(tecla));
^

SGaist

Because key is not a QGestureRecognizer it's a QGesture *. The recognizer's role is to recognize a gesture. You then have to handle the gesture itself. If you wrote a subclass of QGesture then you must cast the pointer accordingly.

Karen Zurutuza

I changed my cast to:

if (QGesture key = event->gesture(Qt::CustomGesture))
KeyTriggered(static_cast<Gestkey>(key));
return true;

error: invalid static_cast from type 'QGesture*' to type 'GestoTecla*'

There is an example of where I can base ?

SGaist

Can you show your class and its implementation ?