PinchHandler

Since: BlackBerry 10.0.0

#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);
             }
         }
     ]
 }


Overview

QML properties

Only has inherited QML properties

attachedObjects: QDeclarativeListProperty< QObject > [read-only]Inherited
objectName: QStringInherited
parent: QObject [read-only]Inherited
ui: bb::cascades::UIConfig [read-only]Inherited

Properties Index

Only has inherited properties

QDeclarativeListProperty< QObject >attachedObjects [read-only]Inherited
QStringobjectNameInherited
QObjectparent [read-only]Inherited
bb::cascades::UIConfigui [read-only]Inherited

Public Functions Index

PinchHandler (bb::cascades::UIObject *parent=0)
virtual ~PinchHandler ()
virtual boolevent (QEvent *event)Inherited
voidsetObjectName (const QString &name)Inherited
virtual Q_INVOKABLE QStringtoDebugString () const Inherited
Q_INVOKABLE bb::cascades::UIConfig *ui () const Inherited

Static Public Functions Index

Buildercreate ()

Protected Functions Index

Only has inherited protected functions

BaseObject (QObject *parent=0)Inherited
virtual voidconnectNotify (const char *signal)Inherited
virtual voiddisconnectNotify (const char *signal)Inherited

Signals Index

voidpinchCancelled ()
voidpinchEnded (bb::cascades::PinchEvent *event)
voidpinchStarted (bb::cascades::PinchEvent *event)
voidpinchUpdated (bb::cascades::PinchEvent *event)
voidcreationCompleted ()Inherited
voidobjectNameChanged (const QString &objectName)Inherited

Properties

(Only has inherited properties)

QDeclarativeListProperty< QObject > attachedObjectsInherited[read-only]

A hierarchical list of the UIObject's attached objects.

Since:

BlackBerry 10.0.0

QString objectNameInherited

This property is overridden from QObject.

See also:

QObject::objectName().

Since:

BlackBerry 10.0.0

QObject parentInherited[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

bb::cascades::UIConfig uiInherited[read-only]

An object that gives access to unit conversion routines.

QML use:
        // Size using design units
        Container {
            preferredWidth: ui.du(12)
            preferredHeight: ui.du(5)
        }

        // Size using design units, snap to whole pixels
        Container {
            preferredWidth: ui.sdu(13.5)
            preferredHeight: ui.sdu(7.5)
        }

        // Size using absolute pixel values
        Container {
            preferredWidth: ui.px(150)
            preferredHeight: ui.px(50)
        }
C++ use:
Container *container1 = Container::create().background(Color::Red);
UIConfig *ui = container1->ui();
container1->setPreferredWidth(ui->du(12));
container1->setPreferredHeight(ui->du(5));

Container *container2 = Container::create().background(Color::Green);
container2->setPreferredWidth(ui->sdu(13.5));
container2->setPreferredHeight(ui->sdu(7.5));

Container *container3 = Container::create().background(Color::Blue);
container3->setPreferredWidth(ui->px(150));
container3->setPreferredHeight(ui->sdu(50));
Since:

Blackberry 10.3.0

Public Functions

PinchHandler (

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 (Inherited

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 (Inherited

Sets the objectName property.

Parameters
name

The new name for the object.

Since:

BlackBerry 10.0.0

virtual Q_INVOKABLE QString toDebugString ()Inherited

Returns a debug string representing this object.

Return:

A debug string for the object.

Since:

BlackBerry 10.0.0

Q_INVOKABLE bb::cascades::UIConfig * ui ()Inherited

Returns the UIConfig for this ui object.

The UIConfig can be used to perform unit conversions from design units (du) and snapped design units (sdu) to pixels.

Ownership remains with Cascades.

C++ use:
Container *container1 = Container::create().background(Color::Red);
UIConfig *ui = container1->ui();
container1->setPreferredWidth(ui->du(12));
container1->setPreferredHeight(ui->du(5));

Container *container2 = Container::create().background(Color::Green);
container2->setPreferredWidth(ui->sdu(13.5));
container2->setPreferredHeight(ui->sdu(7.5));

Container *container3 = Container::create().background(Color::Blue);
container3->setPreferredWidth(ui->px(150));
container3->setPreferredHeight(ui->sdu(50));
Return:

The UIConfig for this ui object.

Since:

BlackBerry 10.3.0

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 (Inherited

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)
Inherited

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)
Inherited

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 pinchCancelled ()

Emitted when the gesture is cancelled.

A gesture can be cancelled for example if another window or a dialog is shown on top of the window the user is interacting with, or if the phone gets locked, etc. If the pinch gesture is cancelled, the effect of the gesture should be disregarded (reset to the original or some other sane state).

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 pinchEnded (

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 pinchStarted (

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 (

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 creationCompleted ()Inherited

Emitted 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 indicates 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 also:

QmlDocument

Since:

BlackBerry 10.0.0

void objectNameChanged (Inherited

This signal is emitted when the objectName property is changed.

Since:

BlackBerry 10.0.0

Last modified: 2014-09-30



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