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Internal/Contributor docs for the Qt SDK. Note: These are NOT official API docs; those are found at https://doc.qt.io/
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QPinchGesture Class Reference

The QPinchGesture class describes a pinch gesture made by the user.\inmodule QtWidgets. More...

#include <qgesture.h>

Inheritance diagram for QPinchGesture:
Collaboration diagram for QPinchGesture:

Public Types

enum  ChangeFlag { ScaleFactorChanged = 0x1 , RotationAngleChanged = 0x2 , CenterPointChanged = 0x4 }
 This enum describes the changes that can occur to the properties of the gesture object. More...
Public Types inherited from QGesture
enum  GestureCancelPolicy { CancelNone = 0 , CancelAllInContext }
 This enum describes how accepting a gesture can cancel other gestures automatically. More...

Public Member Functions

 QPinchGesture (QObject *parent=nullptr)
 ~QPinchGesture ()
 Destructor.
ChangeFlags totalChangeFlags () const
void setTotalChangeFlags (ChangeFlags value)
ChangeFlags changeFlags () const
void setChangeFlags (ChangeFlags value)
QPointF startCenterPoint () const
QPointF lastCenterPoint () const
QPointF centerPoint () const
void setStartCenterPoint (const QPointF &value)
void setLastCenterPoint (const QPointF &value)
void setCenterPoint (const QPointF &value)
qreal totalScaleFactor () const
qreal lastScaleFactor () const
qreal scaleFactor () const
void setTotalScaleFactor (qreal value)
void setLastScaleFactor (qreal value)
void setScaleFactor (qreal value)
qreal totalRotationAngle () const
qreal lastRotationAngle () const
qreal rotationAngle () const
void setTotalRotationAngle (qreal value)
void setLastRotationAngle (qreal value)
void setRotationAngle (qreal value)
Public Member Functions inherited from QGesture
 QGesture (QObject *parent=nullptr)
 ~QGesture ()
 Destroys the gesture object.
Qt::GestureType gestureType () const
Qt::GestureState state () const
QPointF hotSpot () const
void setHotSpot (const QPointF &value)
bool hasHotSpot () const
void unsetHotSpot ()
void setGestureCancelPolicy (GestureCancelPolicy policy)
GestureCancelPolicy gestureCancelPolicy () const
Public Member Functions inherited from QObject
Q_INVOKABLE QObject (QObject *parent=nullptr)
 Constructs an object with parent object parent.
virtual ~QObject ()
 Destroys the object, deleting all its child objects.
virtual bool event (QEvent *event)
 This virtual function receives events to an object and should return true if the event e was recognized and processed.
virtual bool eventFilter (QObject *watched, QEvent *event)
 Filters events if this object has been installed as an event filter for the watched object.
QString objectName () const
Q_WEAK_OVERLOAD void setObjectName (const QString &name)
 Sets the object's name to name.
void setObjectName (QAnyStringView name)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
QBindable< QString > bindableObjectName ()
bool isWidgetType () const
 Returns true if the object is a widget; otherwise returns false.
bool isWindowType () const
 Returns true if the object is a window; otherwise returns false.
bool isQuickItemType () const
 Returns true if the object is a QQuickItem; otherwise returns false.
bool isQmlObjectType () const
 Returns whether the object has been created by the QML engine or ownership has been explicitly set via QJSEngine::setObjectOwnership().
bool signalsBlocked () const noexcept
 Returns true if signals are blocked; otherwise returns false.
bool blockSignals (bool b) noexcept
 If block is true, signals emitted by this object are blocked (i.e., emitting a signal will not invoke anything connected to it).
QThread * thread () const
 Returns the thread in which the object lives.
bool moveToThread (QThread *thread QT6_DECL_NEW_OVERLOAD_TAIL)
 Changes the thread affinity for this object and its children and returns true on success.
int startTimer (int interval, Qt::TimerType timerType=Qt::CoarseTimer)
 This is an overloaded function that will start a timer of type timerType and a timeout of interval milliseconds.
int startTimer (std::chrono::nanoseconds time, Qt::TimerType timerType=Qt::CoarseTimer)
void killTimer (int id)
 Kills the timer with timer identifier, id.
void killTimer (Qt::TimerId id)
template<typename T>
T findChild (QAnyStringView aName, Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
 Returns the child of this object that can be cast into type T and that is called name, or \nullptr if there is no such object.
template<typename T>
QList< T > findChildren (QAnyStringView aName, Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
 Returns all children of this object with the given name that can be cast to type T, or an empty list if there are no such objects.
template<typename T>
T findChild (Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
template<typename T>
QList< T > findChildren (Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
const QObjectList & children () const
 Returns a list of child objects.
void setParent (QObject *parent)
 Makes the object a child of parent.
void installEventFilter (QObject *filterObj)
 Installs an event filter filterObj on this object.
void removeEventFilter (QObject *obj)
 Removes an event filter object obj from this object.
QMetaObject::Connection connect (const QObject *sender, const char *signal, const char *member, Qt::ConnectionType type=Qt::AutoConnection) const
bool disconnect (const char *signal=nullptr, const QObject *receiver=nullptr, const char *member=nullptr) const
bool disconnect (const QObject *receiver, const char *member=nullptr) const
void dumpObjectTree () const
 Dumps a tree of children to the debug output.
void dumpObjectInfo () const
 Dumps information about signal connections, etc.
bool setProperty (const char *name, const QVariant &value)
 Sets the value of the object's name property to value.
bool setProperty (const char *name, QVariant &&value)
QVariant property (const char *name) const
 Returns the value of the object's name property.
QList< QByteArray > dynamicPropertyNames () const
QBindingStorage * bindingStorage ()
const QBindingStorage * bindingStorage () const
QObject * parent () const
 Returns a pointer to the parent object.
bool inherits (const char *classname) const
 Returns true if this object is an instance of a class that inherits className or a QObject subclass that inherits className; otherwise returns false.

Properties

ChangeFlags totalChangeFlags
 the property of the gesture that has change
ChangeFlags changeFlags
 the property of the gesture that has changed in the current step
qreal totalScaleFactor
 the total scale factor
qreal lastScaleFactor
 the last scale factor recorded for this gesture
qreal scaleFactor
 the current scale factor
qreal totalRotationAngle
 the total angle covered by the gesture
qreal lastRotationAngle
 the last reported angle covered by the gesture motion
qreal rotationAngle
 the angle covered by the gesture motion
QPointF startCenterPoint
 the starting position of the center point
QPointF lastCenterPoint
 the last position of the center point recorded for this gesture
QPointF centerPoint
 the current center point
Properties inherited from QGesture
Qt::GestureState state
 the current state of the gesture
Qt::GestureType gestureType
 the type of the gesture
QGesture::GestureCancelPolicy gestureCancelPolicy
 the policy for deciding what happens on accepting a gesture
QPointF hotSpot
 The point that is used to find the receiver for the gesture event.
bool hasHotSpot
 whether the gesture has a hot-spot
Properties inherited from QObject
QString objectName
 the name of this object

Friends

class QPinchGestureRecognizer

Additional Inherited Members

Public Slots inherited from QObject
void deleteLater ()
 \threadsafe
Signals inherited from QObject
void destroyed (QObject *=nullptr)
 This signal is emitted immediately before the object obj is destroyed, after any instances of QPointer have been notified, and cannot be blocked.
void objectNameChanged (const QString &objectName, QPrivateSignal)
 This signal is emitted after the object's name has been changed.
Static Public Member Functions inherited from QObject
static QMetaObject::Connection connect (const QObject *sender, const char *signal, const QObject *receiver, const char *member, Qt::ConnectionType=Qt::AutoConnection)
 \threadsafe
static QMetaObject::Connection connect (const QObject *sender, const QMetaMethod &signal, const QObject *receiver, const QMetaMethod &method, Qt::ConnectionType type=Qt::AutoConnection)
template<typename Func1, typename Func2>
static QMetaObject::Connection connect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, const typename QtPrivate::ContextTypeForFunctor< Func2 >::ContextType *context, Func2 &&slot, Qt::ConnectionType type=Qt::AutoConnection)
template<typename Func1, typename Func2>
static QMetaObject::Connection connect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, Func2 &&slot)
static bool disconnect (const QObject *sender, const char *signal, const QObject *receiver, const char *member)
 \threadsafe
static bool disconnect (const QObject *sender, const QMetaMethod &signal, const QObject *receiver, const QMetaMethod &member)
static bool disconnect (const QMetaObject::Connection &)
 Disconnect a connection.
template<typename Func1, typename Func2>
static bool disconnect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, const typename QtPrivate::FunctionPointer< Func2 >::Object *receiver, Func2 slot)
template<typename Func1>
static bool disconnect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, const QObject *receiver, void **zero)
Protected Member Functions inherited from QGesture
 QGesture (QGesturePrivate &dd, QObject *parent)
Protected Member Functions inherited from QObject
QObject * sender () const
 Returns a pointer to the object that sent the signal, if called in a slot activated by a signal; otherwise it returns \nullptr.
int senderSignalIndex () const
int receivers (const char *signal) const
 Returns the number of receivers connected to the signal.
bool isSignalConnected (const QMetaMethod &signal) const
virtual void timerEvent (QTimerEvent *event)
 This event handler can be reimplemented in a subclass to receive timer events for the object.
virtual void childEvent (QChildEvent *event)
 This event handler can be reimplemented in a subclass to receive child events.
virtual void customEvent (QEvent *event)
 This event handler can be reimplemented in a subclass to receive custom events.
virtual void connectNotify (const QMetaMethod &signal)
virtual void disconnectNotify (const QMetaMethod &signal)
 QObject (QObjectPrivate &dd, QObject *parent=nullptr)
Protected Attributes inherited from QObject
QScopedPointer< QObjectData > d_ptr
Related Symbols inherited from QObject
 Returns the given object cast to type T if the object is of type T (or of a subclass); otherwise returns \nullptr.
 \macro Q_CLASSINFO(Name, Value)

Detailed Description

The QPinchGesture class describes a pinch gesture made by the user.

\inmodule QtWidgets.

Since
4.6

A pinch gesture is a form of touch user input in which the user typically touches two points on the input device with a thumb and finger, before moving them closer together or further apart to change the scale factor, zoom, or level of detail of the user interface.

For an overview of gesture handling in Qt and information on using gestures in your applications, see the \l{Gestures in Widgets and Graphics View} document.

{Demonstration of pinch gesture with two fingers}

Instead of repeatedly applying the same pinching gesture, the user may continue to touch the input device in one place, and apply a second touch to a new point, continuing the gesture. When this occurs, gesture events will continue to be delivered to the target object, containing an instance of QPinchGesture in the Qt::GestureUpdated state.

See also
QPanGesture, QSwipeGesture

Definition at line 103 of file qgesture.h.

Member Enumeration Documentation

◆ ChangeFlag

enum QPinchGesture::ChangeFlag

This enum describes the changes that can occur to the properties of the gesture object.

\value ScaleFactorChanged The scale factor held by scaleFactor changed. \value RotationAngleChanged The rotation angle held by rotationAngle changed. \value CenterPointChanged The center point held by centerPoint changed.

See also
changeFlags, totalChangeFlags
Enumerator
ScaleFactorChanged 
RotationAngleChanged 
CenterPointChanged 

Definition at line 109 of file qgesture.h.

Constructor & Destructor Documentation

◆ QPinchGesture()

QPinchGesture::QPinchGesture ( QObject * parent = nullptr)
explicit

Definition at line 462 of file qgesture.cpp.

◆ ~QPinchGesture()

QPinchGesture::~QPinchGesture ( )

Destructor.

Definition at line 471 of file qgesture.cpp.

Member Function Documentation

◆ centerPoint()

QPointF QPinchGesture::centerPoint ( ) const

Definition at line 505 of file qgesture.cpp.

◆ changeFlags()

QPinchGesture::ChangeFlags QPinchGesture::changeFlags ( ) const

Definition at line 485 of file qgesture.cpp.

◆ lastCenterPoint()

QPointF QPinchGesture::lastCenterPoint ( ) const

Definition at line 500 of file qgesture.cpp.

◆ lastRotationAngle()

qreal QPinchGesture::lastRotationAngle ( ) const

Definition at line 562 of file qgesture.cpp.

◆ lastScaleFactor()

qreal QPinchGesture::lastScaleFactor ( ) const

Definition at line 531 of file qgesture.cpp.

◆ rotationAngle()

qreal QPinchGesture::rotationAngle ( ) const

Definition at line 567 of file qgesture.cpp.

◆ scaleFactor()

qreal QPinchGesture::scaleFactor ( ) const

Definition at line 536 of file qgesture.cpp.

◆ setCenterPoint()

void QPinchGesture::setCenterPoint ( const QPointF & value)

Definition at line 520 of file qgesture.cpp.

◆ setChangeFlags()

void QPinchGesture::setChangeFlags ( ChangeFlags value)

Definition at line 490 of file qgesture.cpp.

◆ setLastCenterPoint()

void QPinchGesture::setLastCenterPoint ( const QPointF & value)

Definition at line 515 of file qgesture.cpp.

◆ setLastRotationAngle()

void QPinchGesture::setLastRotationAngle ( qreal value)

Definition at line 577 of file qgesture.cpp.

◆ setLastScaleFactor()

void QPinchGesture::setLastScaleFactor ( qreal value)

Definition at line 546 of file qgesture.cpp.

◆ setRotationAngle()

void QPinchGesture::setRotationAngle ( qreal value)

Definition at line 582 of file qgesture.cpp.

◆ setScaleFactor()

void QPinchGesture::setScaleFactor ( qreal value)

Definition at line 551 of file qgesture.cpp.

◆ setStartCenterPoint()

void QPinchGesture::setStartCenterPoint ( const QPointF & value)

Definition at line 510 of file qgesture.cpp.

◆ setTotalChangeFlags()

void QPinchGesture::setTotalChangeFlags ( ChangeFlags value)

Definition at line 480 of file qgesture.cpp.

◆ setTotalRotationAngle()

void QPinchGesture::setTotalRotationAngle ( qreal value)

Definition at line 572 of file qgesture.cpp.

◆ setTotalScaleFactor()

void QPinchGesture::setTotalScaleFactor ( qreal value)

Definition at line 541 of file qgesture.cpp.

◆ startCenterPoint()

QPointF QPinchGesture::startCenterPoint ( ) const

Definition at line 495 of file qgesture.cpp.

◆ totalChangeFlags()

QPinchGesture::ChangeFlags QPinchGesture::totalChangeFlags ( ) const

Definition at line 475 of file qgesture.cpp.

◆ totalRotationAngle()

qreal QPinchGesture::totalRotationAngle ( ) const

Definition at line 557 of file qgesture.cpp.

◆ totalScaleFactor()

qreal QPinchGesture::totalScaleFactor ( ) const

Definition at line 526 of file qgesture.cpp.

◆ QPinchGestureRecognizer

friend class QPinchGestureRecognizer
friend

Definition at line 164 of file qgesture.h.

Property Documentation

◆ centerPoint

QPointF QPinchGesture::centerPoint
readwrite

the current center point

The center point is the midpoint between the two input points in the gesture.

See also
startCenterPoint, lastCenterPoint

Definition at line 131 of file qgesture.h.

◆ changeFlags

ChangeFlags QPinchGesture::changeFlags
readwrite

the property of the gesture that has changed in the current step

This property indicates which of the other properties has changed since the previous gesture event included information about this gesture. You can use this information to determine which aspect of your user interface needs to be updated.

See also
totalChangeFlags, scaleFactor, rotationAngle, centerPoint

Definition at line 119 of file qgesture.h.

◆ lastCenterPoint

QPointF QPinchGesture::lastCenterPoint
readwrite

the last position of the center point recorded for this gesture

See also
centerPoint, startCenterPoint

Definition at line 130 of file qgesture.h.

◆ lastRotationAngle

qreal QPinchGesture::lastRotationAngle
readwrite

the last reported angle covered by the gesture motion

The last rotation angle is the angle as reported in the \l rotationAngle property when a previous gesture event was delivered for this gesture.

See also
rotationAngle, totalRotationAngle

Definition at line 126 of file qgesture.h.

◆ lastScaleFactor

qreal QPinchGesture::lastScaleFactor
readwrite

the last scale factor recorded for this gesture

The last scale factor contains the scale factor reported in the \l scaleFactor property when a previous gesture event included information about this gesture.

If no previous event was delivered with information about this gesture (i.e., this gesture object contains information about the first movement in the gesture) then this property contains zero.

See also
scaleFactor, totalScaleFactor

Definition at line 122 of file qgesture.h.

◆ rotationAngle

qreal QPinchGesture::rotationAngle
readwrite

the angle covered by the gesture motion

See also
totalRotationAngle, lastRotationAngle

Definition at line 127 of file qgesture.h.

◆ scaleFactor

qreal QPinchGesture::scaleFactor
readwrite

the current scale factor

The scale factor measures the scale factor associated with the distance between two of the user's inputs on a touch device.

See also
totalScaleFactor, lastScaleFactor

Definition at line 123 of file qgesture.h.

◆ startCenterPoint

QPointF QPinchGesture::startCenterPoint
readwrite

the starting position of the center point

See also
centerPoint, lastCenterPoint

Definition at line 129 of file qgesture.h.

◆ totalChangeFlags

ChangeFlags QPinchGesture::totalChangeFlags
readwrite

the property of the gesture that has change

This property indicates which of the other properties has changed since the gesture has started. You can use this information to determine which aspect of your user interface needs to be updated.

See also
changeFlags, scaleFactor, rotationAngle, centerPoint

Definition at line 118 of file qgesture.h.

◆ totalRotationAngle

qreal QPinchGesture::totalRotationAngle
readwrite

the total angle covered by the gesture

This total angle measures the complete angle covered by the gesture. Usually, this is equal to the value held by the \l rotationAngle property, except in the case where the user performs multiple rotations by removing and repositioning one of the touch points, as described above. In this case, the total angle will be the sum of the rotation angles for the multiple stages of the gesture.

See also
rotationAngle, lastRotationAngle

Definition at line 125 of file qgesture.h.

◆ totalScaleFactor

qreal QPinchGesture::totalScaleFactor
readwrite

the total scale factor

The total scale factor measures the total change in scale factor from the original value to the current scale factor.

See also
scaleFactor, lastScaleFactor

Definition at line 121 of file qgesture.h.

The documentation for this class was generated from the following files: