PinchHandler

#include <bb/cascades/PinchHandler>

A pinch handler can be used to react to pinch gesture.

A pinch gesture goes through the following stages:

pinch gesture is started when user places second finger on the screen; at that moment pinchStarted() signal is emitted from the handler.
pinch gesture is updated when the user moves one or both fingers; at that moment a pinchUpdated() signal is emitted from the handler. Note that this stage is optional and does not happen if the user lifts one or both fingers off the screen without moving them or if the gesture is cancelled.
pinch gesture ends when the user lifts one or both fingers off the screen, at which point a pinchEnded() signal is emitted. This is one of two possible end stages of the pinch gesture and it may not happen if the gesture is cancelled.
pinch gesture is cancelled, a pinchCancelled() signal is emitted. This is the second possible end stage for the pinch gesture. A pinch gesture may be cancelled under certain conditions such as when interaction is cancelled due to a system event.

Example of how to connect a pinch handler to a visual node:

Container* pContainer = Container::create();

PinchHandler *pPinchHandler = PinchHandler::create()
    .onPinch(pMyObject,
             SLOT(onPinchStarted(bb::cascades::PinchEvent*)),
             SLOT(onPinchUpdated(bb::cascades::PinchEvent*)),
             SLOT(onPinchEnded(bb::cascades::PinchEvent*)),
             SLOT(onPinchCancelled()));

pContainer->addGestureHandler(pPinchHandler);

Example of how to connect a pinch handler to a visual node in QML:

Container {
    gestureHandlers: [
        PinchHandler {
            onPinchStarted: {
                console.log("midPointX: "+event.midPointX+" midPointY: "+event.midPointY +" pinchRatio: "
                     +event.pinchRatio +" rotation:" +event.rotation + " distance:"+event.distance);
            }
            onPinchUpdated: {
                console.log("midPointX: "+event.midPointX+" midPointY: "+event.midPointY +" pinchRatio: "
                     +event.pinchRatio +" rotation:" +event.rotation + " distance:"+event.distance);
            }
            onPinchEnded: {
                console.log("midPointX: "+event.midPointX+" midPointY: "+event.midPointY +" pinchRatio: "
                     +event.pinchRatio +" rotation:" +event.rotation + " distance:"+event.distance);
            }
            onPinchCancelled: {
                console.log("midPointX: "+event.midPointX+" midPointY: "+event.midPointY +" pinchRatio: "
                    +event.pinchRatio +" rotation:" +event.rotation + " distance:"+event.distance);
            }
        }
    ]
}

See:

VisualNode::addGestureHandler()

Since:

BlackBerry 10.0.0

Inheritance

bb::cascades::BaseObject
	bb::cascades::UIObject
		bb::cascades::GestureHandler
			bb::cascades::PinchHandler

QML properties

Only has inherited QML properties

attachedObjects	: QDeclarativeListProperty< QObject > [read-only]
objectName	: QString
parent	: QObject [read-only]

QML signals

onPinchStarted	: {}
onPinchUpdated	: {}
onPinchEnded	: {}
onPinchCancelled	: {}
onCreationCompleted	: {}
onObjectNameChanged	: {}

Properties Index

Only has inherited properties

QDeclarativeListProperty< QObject >	attachedObjects [read-only]
QString	objectName
QObject	parent [read-only]

Public Functions Index

	PinchHandler (bb::cascades::UIObject *parent=0)
virtual	~PinchHandler ()
virtual bool	event (QEvent *event)
void	setObjectName (const QString &name)
virtual Q_INVOKABLE QString	toDebugString () const

Static Public Functions Index

Builder

create ()

Protected Functions Index

Only has inherited protected functions

	BaseObject (QObject *parent=0)
virtual void	connectNotify (const char *signal)
virtual void	disconnectNotify (const char *signal)

Signals Index

void	pinchStarted (bb::cascades::PinchEvent *event)
void	pinchUpdated (bb::cascades::PinchEvent *event)
void	pinchEnded (bb::cascades::PinchEvent *event)
void	pinchCancelled ()
void	creationCompleted ()
void	objectNameChanged (const QString &objectName)

Properties

(Only has inherited properties)

QDeclarativeListProperty< QObject > attachedObjects[read-only]

A hierarchical list of the UIObject's attached objects.

This QDeclarativeListProperty can contain any QObject. When a QObject is added to property, the UIObject takes ownership of the attached object.

This feature is typically used from QML to specify business logic object or any other shared objects for the subnodes of this UIObject. In C++ the same functionality can be achived by setting a parent of a QObject to be attached to the QObject which is going to own it.

QML usage example (MyObject is a custom class registered for QML using the qmlRegisterType() function):

Container {
    Label { text: "Title: " + myObject.title } 
    Label { text: "Subject: " + myObject.subject }
    attachedObjects: [
        MyObject { id: myObject
            title: "Hello World"
            subject: "Nice Day"
        }
    ]
}

Since:

BlackBerry 10.0.0

QString objectName

This property is overridden from QObject.

As the objectName property is overridden from the QObject class, this signal will not be emitted if setObjectName() function is called directly on QObject.

The default value of this property is QString::null.

See:

QObject::objectName().

Since:

BlackBerry 10.0.0

QObject parent[read-only]

A read-only property that represents this object's parent.

The parent of an object is specified using QObject::setParent(QObject*). The purpose of the property is to expose the object's parent to QML.

This property is read-only to prevent modifications from QML, where typically the parent is declaratively set. In C++ code, the parent can be explicitly set using QObject::setParent(QObject*), or implicitly set by adding it to a visual container.

The default value of this property is 0.

Since:

BlackBerry 10.0.0

Public Functions

PinchHandler (
bb::cascades::UIObject *parent)

Creates a PinchHandler.

Parameters
parent	The parent UIObject, or 0. This parameter is optional and defaults to 0 if not specified.

Since:

BlackBerry 10.0.0

virtual~PinchHandler ()

Destructor.

Since:

BlackBerry 10.0.0

virtual bool event (
QEvent *event)

Overloaded to implement the event mechanism in Cascades.

Warning:

If this function is overridden, it must be called by the derived class for events to work properly in Cascades.

Parameters
event	The received event.

Return:

True if the received event was recognized and processed, false otherwise.

Since:

BlackBerry 10.0.0

void setObjectName (
const QString &name)

Sets the objectName property.

Parameters
name	The new name for the object.

Since:

BlackBerry 10.0.0

virtual Q_INVOKABLE QString toDebugString ()

Returns a debug string representing this object.

Return:

A debug string for the object.

Since:

BlackBerry 10.0.0

Static Public Functions

Builder create ()

Creates and returns a builder for constructing a pinchHandler.

Using the builder to create a PinchHandler:

PinchHandler *pPinchHandler = PinchHandler::create();

Return:

A Builder used for constructing a PinchHandler.

Since:

BlackBerry 10.0.0

Protected Functions

(Only has inherited protected functions)

BaseObject (
QObject *parent)

Constructs an instance of BaseObject's subclass.

Parameters
parent	An optional parent, defaults to 0.

Since:

BlackBerry 10.0.0

virtual void connectNotify (
const char *signal)

Overloaded to implement the event mechanism in Cascades.

If this function is overridden, it must be called by the derived class for events to work properly in Cascades.

Parameters
signal	The connected signal.

Since:

BlackBerry 10.0.0

virtual void disconnectNotify (
const char *signal)

Overloaded to implement the event mechanism in Cascades.

If this function is overridden, it must be called by the derived class for events to work properly in Cascades.

Parameters
signal	The disconnected signal.

Since:

BlackBerry 10.0.0

Signals

void pinchStarted (
bb::cascades::PinchEvent *event)

Emitted at the start of the pinch gesture, specifically when the second finger was placed on the screen.

Parameters
event	the pinch event with current pinch parameters.

Since:

BlackBerry 10.0.0

void pinchUpdated (
bb::cascades::PinchEvent *event)

Emitted after the gesture started, when one or both fingers moved.

This signal will not be emitted if the user just places two fingers and lifts them without moving.

Parameters
event	The pinch event with current pinch parameters.

Since:

BlackBerry 10.0.0

void pinchEnded (
bb::cascades::PinchEvent *event)

Emitted when the user lifts one or both fingers off the screen.

This signal is one of the two possible outcomes of a pinch gesture, the other being the cancelation of the gesture (pinchCancelled() is emitted).

Parameters
event	the pinch event with current pinch parameters

Since:

BlackBerry 10.0.0

void pinchCancelled ()

Emitted when the gesture is cancelled.

TODO [dtrembovetski] EXPLANATION NEEDED.

This signal is one of the two possible outcomes of a pinch gesture, the other being the gesture ended (pinchEnded() is emitted).

Since:

BlackBerry 10.0.0

void creationCompleted ()

This signal is emitted only when this object is instantiated as a result of loading a QML document and creating the root node, or when an object is being constructed using its builder class.

This signal is emitted only when this object is instantiated as a result of loading a QML document and creating the root node (only after the root component that caused this instantiation has completed construction), or when the object is being constructed from its builder class. This signal is emitted to indicate that the construction and initialization of the object has been completed, the properties are initialized, and any QML binding values have been assigned to the object.

This signal is not emitted when the object is constructed from C++ using the constructor. If the object is constructed using its builder class, the signal is emitted when the the builder class returns the fully constructed object.

This signal can be used when there is an activity that needs to be performed, such as a property state integrity verification after the object is instantiated from a QML document or a builder, but before control is returned to the application.

See:

QmlDocument

Since:

BlackBerry 10.0.0

void objectNameChanged (
const QString &objectName)

This signal is emitted when the objectName property is changed.

See:

QObject, BaseObject::objectName.

Since:

BlackBerry 10.0.0

PinchHandler

Inheritance

QML properties

QML signals

Properties Index

Public Functions Index

Static Public Functions Index

Protected Functions Index

Signals Index

Properties

QDeclarativeListProperty< QObject > attachedObjects[read-only]

QString objectName

QObject parent[read-only]

Public Functions

PinchHandler (bb::cascades::UIObject *parent)

virtual~PinchHandler ()

virtual bool event (QEvent *event)

void setObjectName (const QString &name)

virtual Q_INVOKABLE QString toDebugString ()

Static Public Functions

Builder create ()

Protected Functions

BaseObject (QObject *parent)

virtual void connectNotify (const char *signal)

virtual void disconnectNotify (const char *signal)

Signals

void pinchStarted (bb::cascades::PinchEvent *event)

void pinchUpdated (bb::cascades::PinchEvent *event)

void pinchEnded (bb::cascades::PinchEvent *event)

void pinchCancelled ()

void creationCompleted ()

void objectNameChanged (const QString &objectName)

PinchHandler (
bb::cascades::UIObject *parent)

virtual bool event (
QEvent *event)

void setObjectName (
const QString &name)

BaseObject (
QObject *parent)

virtual void connectNotify (
const char *signal)

virtual void disconnectNotify (
const char *signal)

void pinchStarted (
bb::cascades::PinchEvent *event)

void pinchUpdated (
bb::cascades::PinchEvent *event)

void pinchEnded (
bb::cascades::PinchEvent *event)

void objectNameChanged (
const QString &objectName)