QScroller Class Reference

The QScroller class enables kinetic scrolling for any scrolling widget or graphics item. More...

#include <qscroller.h>

Inheritance diagram for QScroller:

Collaboration diagram for QScroller:

Public Types
enum	State { Inactive , Pressed , Dragging , Scrolling }
	This enum contains the different QScroller states. More...
enum	ScrollerGestureType { TouchGesture , LeftMouseButtonGesture , RightMouseButtonGesture , MiddleMouseButtonGesture }
	This enum contains the different gesture types that are supported by the QScroller gesture recognizer. More...
enum	Input { InputPress = 1 , InputMove , InputRelease }
	This enum contains an input device agnostic view of input events that are relevant for QScroller. More...

Public Slots
void	setScrollerProperties (const QScrollerProperties &prop)
void	scrollTo (const QPointF &pos)
	Starts scrolling the widget so that point pos is at the top-left position in the viewport.
void	scrollTo (const QPointF &pos, int scrollTime)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.This version will reach its destination position in scrollTime milliseconds.
void	ensureVisible (const QRectF &rect, qreal xmargin, qreal ymargin)
	Starts scrolling so that the rectangle rect is visible inside the viewport with additional margins specified in pixels by xmargin and ymargin around the rect.
void	ensureVisible (const QRectF &rect, qreal xmargin, qreal ymargin, int scrollTime)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.This version will reach its destination position in scrollTime milliseconds.
void	resendPrepareEvent ()
	This function resends the QScrollPrepareEvent.
Public Slots inherited from QObject
void	deleteLater ()
	\threadsafe

Signals
void	stateChanged (QScroller::State newstate)
	QScroller emits this signal whenever the state changes.
void	scrollerPropertiesChanged (const QScrollerProperties &)
	QScroller emits this signal whenever its scroller properties change.
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.

Public Member Functions
QObject *	target () const
	Returns the target object of this scroller.
State	state () const
bool	handleInput (Input input, const QPointF &position, qint64 timestamp=0)
	This function is used by gesture recognizers to inform the scroller about a new input event.
void	stop ()
	Stops the scroller and resets its state back to Inactive.
QPointF	velocity () const
	Returns the current scrolling velocity in meter per second when the state is Scrolling or Dragging.
QPointF	finalPosition () const
	Returns the estimated final position for the current scroll movement.
QPointF	pixelPerMeter () const
	Returns the pixel per meter metric for the scrolled widget.
QScrollerProperties	scrollerProperties () const
void	setSnapPositionsX (const QList< qreal > &positions)
	Set the snap positions for the horizontal axis to a list of positions.
void	setSnapPositionsX (qreal first, qreal interval)
	Set the snap positions for the horizontal axis to regular spaced intervals.
void	setSnapPositionsY (const QList< qreal > &positions)
	Set the snap positions for the vertical axis to a list of positions.
void	setSnapPositionsY (qreal first, qreal interval)
	Set the snap positions for the vertical axis to regular spaced intervals.
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	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.
void	moveToThread (QThread *thread)
	Changes the thread affinity for this object and its children.
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::milliseconds time, Qt::TimerType timerType=Qt::CoarseTimer)
void	killTimer (int id)
	Kills the timer with timer identifier, id.
template<typename T >
T	findChild (const QString &aName=QString(), 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 (const QString &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 >
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.

Static Public Member Functions
static bool	hasScroller (QObject *target)
	Returns true if a QScroller object was already created for target; false otherwise.
static QScroller *	scroller (QObject *target)
	Returns the scroller for the given target.
static const QScroller *	scroller (const QObject *target)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. This is the const version of scroller().
static Qt::GestureType	grabGesture (QObject *target, ScrollerGestureType gestureType=TouchGesture)
	Registers a custom scroll gesture recognizer, grabs it for the target and returns the resulting gesture type.
static Qt::GestureType	grabbedGesture (QObject *target)
	Returns the gesture type currently grabbed for the target or 0 if no gesture is grabbed.
static void	ungrabGesture (QObject *target)
	Ungrabs the gesture for the target.
static QList< QScroller * >	activeScrollers ()
	Returns an application wide list of currently active QScroller objects.
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)

Properties
State	state
	the state of the scroller
QScrollerProperties	scrollerProperties
	The scroller properties of this scroller.
Properties inherited from QObject
QString	objectName
	the name of this object

Private Member Functions
virtual	~QScroller ()

Friends
class	QFlickGestureRecognizer

Additional Inherited Members
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
template< class T > T	qobject_cast (const QObject *object)
	Returns the given object cast to type T if the object is of type T (or of a subclass); otherwise returns \nullptr.
template< typename T > T	qFindChildqFindChildren (const QObject *obj, const QString &name)()
template< typename T > QList< T >	qFindChildrenqFindChildren (const QObject *obj, const QString &name)()
	QObjectList
	\macro Q_CLASSINFO(Name, Value)

Detailed Description

The QScroller class enables kinetic scrolling for any scrolling widget or graphics item.

Since

5.0

\inmodule QtWidgets

With kinetic scrolling, the user can push the widget in a given direction and it will continue to scroll in this direction until it is stopped either by the user or by friction. Aspects of inertia, friction and other physical concepts can be changed in order to fine-tune an intuitive user experience.

The QScroller object is the object that stores the current position and scrolling speed and takes care of updates. QScroller can be triggered by a flick gesture

    QWidget *w = ...;
    QScroller::grabGesture(w, QScroller::LeftMouseButtonGesture);

or directly like this:

    QWidget *w = ...;
    QScroller *scroller = QScroller::scroller(w);
    scroller->scrollTo(QPointF(100, 100));

The scrolled QObjects receive a QScrollPrepareEvent whenever the scroller needs to update its geometry information and a QScrollEvent whenever the content of the object should actually be scrolled.

The scroller uses the global QAbstractAnimation timer to generate its QScrollEvents. This can be changed with QScrollerProperties::FrameRate on a per-QScroller basis.

Even though this kinetic scroller has a large number of settings available via QScrollerProperties, we recommend that you leave them all at their default, platform optimized values. Before changing them you can experiment with the plot example in the scroller examples directory.

See also

QScrollEvent, QScrollPrepareEvent, QScrollerProperties

Definition at line 25 of file qscroller.h.

Member Enumeration Documentation

Input

enum QScroller::Input

This enum contains an input device agnostic view of input events that are relevant for QScroller.

\value InputPress The user pressed the input device (e.g. QEvent::MouseButtonPress, QEvent::GraphicsSceneMousePress, QEvent::TouchBegin)

\value InputMove The user moved the input device (e.g. QEvent::MouseMove, QEvent::GraphicsSceneMouseMove, QEvent::TouchUpdate)

\value InputRelease The user released the input device (e.g. QEvent::MouseButtonRelease, QEvent::GraphicsSceneMouseRelease, QEvent::TouchEnd)

Enumerator
InputPress
InputMove
InputRelease

Definition at line 50 of file qscroller.h.

ScrollerGestureType

enum QScroller::ScrollerGestureType

This enum contains the different gesture types that are supported by the QScroller gesture recognizer.

\value TouchGesture The gesture recognizer will only trigger on touch events. Specifically it will react on single touch points when using a touch screen and dual touch points when using a touchpad. \value LeftMouseButtonGesture The gesture recognizer will only trigger on left mouse button events. \value MiddleMouseButtonGesture The gesture recognizer will only trigger on middle mouse button events. \value RightMouseButtonGesture The gesture recognizer will only trigger on right mouse button events.

Enumerator
TouchGesture
LeftMouseButtonGesture
RightMouseButtonGesture
MiddleMouseButtonGesture

Definition at line 42 of file qscroller.h.

State

enum QScroller::State

This enum contains the different QScroller states.

\value Inactive The scroller is not scrolling and nothing is pressed. \value Pressed A touch event was received or the mouse button was pressed but the scroll area is currently not dragged. \value Dragging The scroll area is currently following the touch point or mouse. \value Scrolling The scroll area is moving on it's own.

Enumerator
Inactive
Pressed
Dragging
Scrolling

Definition at line 33 of file qscroller.h.

Member Function Documentation

~QScroller()

QScroller::~QScroller ( )

privatevirtual

Definition at line 455 of file qscroller.cpp.

References d, and QGestureRecognizer::unregisterRecognizer().

Here is the call graph for this function:

activeScrollers()

QList< QScroller * > QScroller::activeScrollers ( )

static

Returns an application wide list of currently active QScroller objects.

Active QScroller objects are in a state() that is not QScroller::Inactive. This function is useful when writing your own gesture recognizer.

Definition at line 284 of file qscroller.cpp.

Referenced by QFlickGestureRecognizer::recognize().

Here is the caller graph for this function:

ensureVisible [1/2]

void QScroller::ensureVisible ( const QRectF &  rect, qreal  xmargin, qreal  ymargin  )

slot

Starts scrolling so that the rectangle rect is visible inside the viewport with additional margins specified in pixels by xmargin and ymargin around the rect.

In cases where it is not possible to fit the rect plus margins inside the viewport the contents are scrolled so that as much as possible is visible from rect.

The scrolling speed is calculated so that the given position is reached after a platform-defined time span.

This function performs the actual scrolling by calling scrollTo().

See also

scrollTo()

Definition at line 686 of file qscroller.cpp.

References ensureVisible(), and rect.

Referenced by ensureVisible().

Here is the call graph for this function:

Here is the caller graph for this function:

ensureVisible [2/2]

void QScroller::ensureVisible ( const QRectF &  rect, qreal  xmargin, qreal  ymargin, int  scrollTime  )

slot

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.This version will reach its destination position in scrollTime milliseconds.

Definition at line 696 of file qscroller.cpp.

References QRectF::bottom(), clampToRect(), QRectF::contains(), d, Dragging, QRectF::height(), QSizeF::height(), Qt::Horizontal, Inactive, QRectF::left(), Pressed, qCDebug, rect, QRectF::right(), scrollTo(), QPointF::setX(), QPointF::setY(), QRectF::top(), Qt::Vertical, QRectF::width(), and QSizeF::width().

Here is the call graph for this function:

finalPosition()

QPointF QScroller::finalPosition

(

)

const

Returns the estimated final position for the current scroll movement.

Returns the current position if the scroller state is not Scrolling. The result is undefined when the scroller state is Inactive.

The target position is in pixel.

See also

pixelPerMeter(), scrollTo()

Definition at line 601 of file qscroller.cpp.

References d, Qt::Horizontal, and Qt::Vertical.

grabbedGesture()

Qt::GestureType QScroller::grabbedGesture ( QObject *  target )

static

Returns the gesture type currently grabbed for the target or 0 if no gesture is grabbed.

See also

grabGesture(), ungrabGesture()

Definition at line 399 of file qscroller.cpp.

References scroller.

grabGesture()

Qt::GestureType QScroller::grabGesture ( QObject *  target, ScrollerGestureType  scrollGestureType = TouchGesture  )

static

Registers a custom scroll gesture recognizer, grabs it for the target and returns the resulting gesture type.

If scrollGestureType is set to TouchGesture the gesture triggers on touch events. If it is set to one of LeftMouseButtonGesture, RightMouseButtonGesture or MiddleMouseButtonGesture it triggers on mouse events of the corresponding button.

Only one scroll gesture can be active on a single object at the same time. If you call this function twice on the same object, it will ungrab the existing gesture before grabbing the new one.

Note

To avoid unwanted side-effects, mouse events are consumed while the gesture is triggered. Since the initial mouse press event is not consumed, the gesture sends a fake mouse release event at the global position {(INT_MIN, INT_MIN)}. This ensures that internal states of the widget that received the original mouse press are consistent.

See also

ungrabGesture(), grabbedGesture()

Definition at line 355 of file qscroller.cpp.

References button, QWidget::grabGesture(), Qt::LeftButton, LeftMouseButtonGesture, Qt::MiddleButton, MiddleMouseButtonGesture, Qt::NoButton, QFlickGestureRecognizer, QGestureRecognizer::registerRecognizer(), Qt::RightButton, RightMouseButtonGesture, scroller, QWidget::setAttribute(), sp, target(), TouchGesture, ungrabGesture(), Qt::WA_AcceptTouchEvents, and widget.

Referenced by QPixmapStyle::polish().

Here is the call graph for this function:

Here is the caller graph for this function:

handleInput()

bool QScroller::handleInput	(	Input	input,
		const QPointF &	position,
		qint64	timestamp = 0
	)

This function is used by gesture recognizers to inform the scroller about a new input event.

The scroller changes its internal state() according to the input event and its attached scroller properties. The scroller doesn't distinguish between the kind of input device the event came from. Therefore the event needs to be split into the input type, a position and a milli-second timestamp. The position needs to be in the target's coordinate system.

The return value is true if the event should be consumed by the calling filter or false if the event should be forwarded to the control.

Note

Using grabGesture() should be sufficient for most use cases.

Definition at line 942 of file qscroller.cpp.

References d, Dragging, i, Inactive, InputMove, InputPress, InputRelease, QScrollerPrivate::moveWhileDragging(), QScrollerPrivate::moveWhilePressed(), position(), Pressed, QScrollerPrivate::pressWhileInactive(), QScrollerPrivate::pressWhileScrolling(), qCDebug, QScrollerPrivate::releaseWhileDragging(), QScrollerPrivate::releaseWhilePressed(), Scrolling, and state.

Referenced by QFlickGestureRecognizer::recognize().

Here is the call graph for this function:

Here is the caller graph for this function:

hasScroller()

bool QScroller::hasScroller ( QObject *  target )

static

Returns true if a QScroller object was already created for target; false otherwise.

See also

scroller()

Definition at line 242 of file qscroller.cpp.

Referenced by QFlickGesture::QFlickGesture().

Here is the caller graph for this function:

pixelPerMeter()

QPointF QScroller::pixelPerMeter

(

)

const

Returns the pixel per meter metric for the scrolled widget.

The value is reported for both the x and y axis separately by using a QPointF.

Note

Please note that this value should be physically correct. The actual DPI settings that Qt returns for the display may be reported wrongly on purpose by the underlying windowing system, for example on \macos.

Definition at line 521 of file qscroller.cpp.

References d, QLineF::length(), QPointF::rx(), QPointF::ry(), scene, tr, and QGraphicsScene::views().

Here is the call graph for this function:

resendPrepareEvent

void QScroller::resendPrepareEvent ( )

slot

This function resends the QScrollPrepareEvent.

Calling resendPrepareEvent triggers a QScrollPrepareEvent from the scroller. This allows the receiver to re-set content position and content size while scrolling. Calling this function while in the Inactive state is useless as the prepare event is sent again before scrolling starts.

Definition at line 770 of file qscroller.cpp.

References d.

scroller() [1/2]

const QScroller * QScroller::scroller ( const QObject *  target )

static

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. This is the const version of scroller().

Definition at line 274 of file qscroller.cpp.

References scroller.

scroller() [2/2]

QScroller * QScroller::scroller ( QObject *  target )

static

Returns the scroller for the given target.

As long as the object exists this function will always return the same QScroller instance. If no QScroller exists for the target, one will implicitly be created. At no point more than one QScroller will be active on an object.

See also

hasScroller(), target()

Definition at line 255 of file qscroller.cpp.

References contains(), and qWarning.

Referenced by QFlickGesture::QFlickGesture(), and QAbstractItemView::viewportEvent().

Here is the call graph for this function:

Here is the caller graph for this function:

scrollerProperties()

QScrollerProperties QScroller::scrollerProperties

(

)

const

Definition at line 313 of file qscroller.cpp.

References d.

scrollerPropertiesChanged

void QScroller::scrollerPropertiesChanged ( const QScrollerProperties &  newProperties )

signal

QScroller emits this signal whenever its scroller properties change.

newProperties are the new scroller properties.

See also

scrollerProperties

Referenced by setScrollerProperties().

Here is the caller graph for this function:

scrollTo [1/2]

void QScroller::scrollTo ( const QPointF &  pos )

slot

Starts scrolling the widget so that point pos is at the top-left position in the viewport.

The behaviour when scrolling outside the valid scroll area is undefined. In this case the scroller might or might not overshoot.

The scrolling speed will be calculated so that the given position will be reached after a platform-defined time span.

pos is given in viewport coordinates.

See also

ensureVisible()

Definition at line 622 of file qscroller.cpp.

References pos, and scrollTo().

Referenced by ensureVisible(), and scrollTo().

Here is the call graph for this function:

Here is the caller graph for this function:

scrollTo [2/2]

void QScroller::scrollTo ( const QPointF &  pos, int  scrollTime  )

slot

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.This version will reach its destination position in scrollTime milliseconds.

Definition at line 632 of file qscroller.cpp.

References clampToRect(), d, Dragging, Qt::Horizontal, Inactive, pos, Pressed, qCDebug, qIsNaN(), Scrolling, QScrollerPrivate::ScrollTypeScrollTo, QPointF::setX(), QPointF::setY(), time, velocity(), Qt::Vertical, QPointF::x(), and QPointF::y().

Here is the call graph for this function:

setScrollerProperties

void QScroller::setScrollerProperties ( const QScrollerProperties &  prop )

slot

Definition at line 319 of file qscroller.cpp.

References d, emit, scrollerPropertiesChanged(), and sp.

Here is the call graph for this function:

setSnapPositionsX() [1/2]

void QScroller::setSnapPositionsX

(

const QList< qreal > &

positions

)

Set the snap positions for the horizontal axis to a list of positions.

This overwrites all previously set snap positions and also a previously set snapping interval. Snapping can be deactivated by setting an empty list of positions.

Definition at line 781 of file qscroller.cpp.

References d, and positions.

setSnapPositionsX() [2/2]

void QScroller::setSnapPositionsX	(	qreal	first,
		qreal	interval
	)

Set the snap positions for the horizontal axis to regular spaced intervals.

The first snap position is at first. The next at first + interval. This can be used to implement a list header. This overwrites all previously set snap positions and also a previously set snapping interval. Snapping can be deactivated by setting an interval of 0.0

Definition at line 797 of file qscroller.cpp.

References d.

setSnapPositionsY() [1/2]

void QScroller::setSnapPositionsY

(

const QList< qreal > &

positions

)

Set the snap positions for the vertical axis to a list of positions.

This overwrites all previously set snap positions and also a previously set snapping interval. Snapping can be deactivated by setting an empty list of positions.

Definition at line 812 of file qscroller.cpp.

References d, and positions.

setSnapPositionsY() [2/2]

void QScroller::setSnapPositionsY	(	qreal	first,
		qreal	interval
	)

Set the snap positions for the vertical axis to regular spaced intervals.

The first snap position is at first. The next at first + interval. This overwrites all previously set snap positions and also a previously set snapping interval. Snapping can be deactivated by setting an interval of 0.0

Definition at line 827 of file qscroller.cpp.

References d.

state()

QScroller::State QScroller::state

(

)

const

Definition at line 484 of file qscroller.cpp.

References d.

stateChanged

void QScroller::stateChanged ( QScroller::State  newState )

signal

QScroller emits this signal whenever the state changes.

newState is the new State.

See also

state

stop()

void QScroller::stop

(

)

Stops the scroller and resets its state back to Inactive.

Definition at line 493 of file qscroller.cpp.

References clampToRect(), d, Qt::Horizontal, Inactive, qIsNaN(), QPointF::setX(), QPointF::setY(), Qt::Vertical, QPointF::x(), and QPointF::y().

Referenced by QFlickGestureRecognizer::recognize().

Here is the call graph for this function:

Here is the caller graph for this function:

target()

QObject * QScroller::target

(

)

const

Returns the target object of this scroller.

See also

hasScroller(), scroller()

Definition at line 293 of file qscroller.cpp.

References d.

Referenced by grabGesture(), and ungrabGesture().

Here is the caller graph for this function:

ungrabGesture()

void QScroller::ungrabGesture ( QObject *  target )

static

Ungrabs the gesture for the target.

Does nothing if no gesture is grabbed.

See also

grabGesture(), grabbedGesture()

Definition at line 414 of file qscroller.cpp.

References scroller, sp, target(), QWidget::ungrabGesture(), QGestureRecognizer::unregisterRecognizer(), and widget.

Referenced by grabGesture(), and QPixmapStyle::unpolish().

Here is the call graph for this function:

Here is the caller graph for this function:

velocity()

QPointF QScroller::velocity

(

)

const

Returns the current scrolling velocity in meter per second when the state is Scrolling or Dragging.

Returns a zero velocity otherwise.

The velocity is reported for both the x and y axis separately by using a QPointF.

See also

pixelPerMeter()

Definition at line 556 of file qscroller.cpp.

References d, differentialForProgress(), Dragging, now, qSign(), Scrolling, QPointF::setX(), QPointF::setY(), sp, and state.

Referenced by scrollTo().

Here is the call graph for this function:

Here is the caller graph for this function:

Friends And Related Symbol Documentation

QFlickGestureRecognizer

friend class QFlickGestureRecognizer

friend

Definition at line 110 of file qscroller.h.

Referenced by grabGesture().

Property Documentation

scrollerProperties

QScroller::scrollerProperties

readwrite

The scroller properties of this scroller.

The properties are used by the QScroller to determine its scrolling behavior.

Definition at line 114 of file qscroller.h.

Referenced by QFlickGestureRecognizer::recognize().

state

QScroller::state

read

the state of the scroller

See also

QScroller::State

Definition at line 114 of file qscroller.h.

Referenced by QFlickGestureRecognizer::recognize(), and velocity().

---

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

• qtbase/src/widgets/util/qscroller.h
• qtbase/src/widgets/doc/snippets/code/src_widgets_util_qscroller.cpp
• qtbase/src/widgets/util/qscroller.cpp