The QTimeLine class provides a timeline for controlling animations. More...

Inheritance diagram for QTimeLine:

Public Types
enum	CurveShape

enum	Direction

enum	State

Public Signals
void	finished ()

void	frameChanged (int frame)

void	stateChanged (QTimeLine::State newState)

void	valueChanged (qreal value)

Public Signals inherited from QObject
void	destroyed (QObject *obj=nullptr)

void	objectNameChanged (const QString &objectName)

Public Slots
void	resume ()

void	setCurrentTime (int msec)

void	setPaused (bool paused)

void	start ()

void	stop ()

void	toggleDirection ()

Public Slots inherited from QObject
void	deleteLater ()

Public Methods
	QTimeLine (int duration=1000, QObject *parent=nullptr)

virtual	~QTimeLine ()

int	currentFrame () const

int	currentTime () const

qreal	currentValue () const

CurveShape	curveShape () const

Direction	direction () const

int	duration () const

QEasingCurve	easingCurve () const

int	endFrame () const

int	frameForTime (int msec) const

int	loopCount () const

void	setCurveShape (CurveShape shape)

void	setDirection (Direction direction)

void	setDuration (int duration)

void	setEasingCurve (const QEasingCurve &curve)

void	setEndFrame (int frame)

void	setFrameRange (int startFrame, int endFrame)

void	setLoopCount (int count)

void	setStartFrame (int frame)

void	setUpdateInterval (int interval)

int	startFrame () const

State	state () const

int	updateInterval () const

virtual qreal	valueForTime (int msec) const

Public Methods inherited from QObject
	QObject (QObject *parent=nullptr)

	~QObject ()

bool	blockSignals (bool block)

const QList< QObject * > &	children () const

bool	connect (const QObject *sender, const QString &signalMethod, const QString &location, const QString &slotMethod, Qt::ConnectionType type=Qt::AutoConnection)

bool	connect (const QObject *sender, const QString &signalMethod, const QString &slotMethod, Qt::ConnectionType type=Qt::AutoConnection)

bool	disconnect (const QObject *receiver, const QString &slotMethod=QString ()) const

bool	disconnect (const QString &signalMethod, const QString &location, const QObject *receiver=nullptr, const QString &slotMethod=QString ()) const

bool	disconnect (const QString &signalMethod=QString (), const QObject *receiver=nullptr, const QString &slotMethod=QString ()) const

void	dumpObjectInfo ()

void	dumpObjectTree ()

QList< QString >	dynamicPropertyNames () const

virtual bool	event (QEvent *event)

virtual bool	eventFilter (QObject watched, QEvent event)

template<typename T >
T	findChild (const QString &childName=QString ()) const

template<class T >
QList< T >	findChildren (const QRegularExpression &regExp, Qt::FindChildOptions options=Qt::FindChildrenRecursively) const

template<class T >
QList< T >	findChildren (const QString &childName=QString (), Qt::FindChildOptions options=Qt::FindChildrenRecursively) const

bool	inherits (const QString &className) const

void	installEventFilter (QObject *filterObj)

bool	isWidgetType () const

bool	isWindowType () const

void	killTimer (int id)

const QMetaObject *	metaObject () const

void	moveToThread (QThread *targetThread)

QString	objectName () const

QObject *	parent () const

template<class T = QVariant>
T	property (const QString &name) const

void	removeEventFilter (QObject *obj)

void	setObjectName (const QString &name)

void	setParent (QObject *parent)

bool	setProperty (const QString &name, const QVariant &value)

bool	signalsBlocked () const

int	startTimer (int interval, Qt::TimerType timerType=Qt::CoarseTimer)

QThread *	thread () const

Protected Methods
void	timerEvent (QTimerEvent *event) override

Protected Methods inherited from QObject
virtual void	childEvent (QChildEvent *event)

virtual void	connectNotify (const QMetaMethod &signalMethod) const

virtual void	customEvent (QEvent *event)

virtual void	disconnectNotify (const QMetaMethod &signalMethod) const

bool	isSignalConnected (const QMetaMethod &signalMethod) const

int	receivers (const QString &signal) const

QObject *	sender () const

int	senderSignalIndex () const

Properties
	currentTime

	curveShape

	direction

	duration

	easingCurve

	loopCount

	updateInterval

Properties inherited from QObject
	objectName

Additional Inherited Members
Static Public Methods inherited from QObject
static bool	connect (const QObject sender, const QMetaMethod &signalMethod, const QObject receiver, const QMetaMethod &slotMethod, Qt::ConnectionType type=Qt::AutoConnection)

static bool	connect (const QObject sender, const QString &signalMethod, const QObject receiver, const QString &slotMethod, Qt::ConnectionType type=Qt::AutoConnection, const QString &location=QString ())

static bool	connect (const QObject sender, const QString &signalMethod, const QString &location, const QObject receiver, const QString &slotMethod, Qt::ConnectionType type=Qt::AutoConnection)

template<class Sender , class SignalClass , class... SignalArgs, class Receiver , class SlotClass , class... SlotArgs, class SlotReturn >
static bool	connect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver receiver, SlotReturn (SlotClass::slotMethod)(SlotArgs...), Qt::ConnectionType type=Qt::AutoConnection)

template<class Sender , class SignalClass , class... SignalArgs, class Receiver , class T >
static bool	connect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver *receiver, T slotLambda, Qt::ConnectionType type=Qt::AutoConnection)

static bool	disconnect (const QObject sender, const QMetaMethod &signalMethod, const QObject receiver, const QMetaMethod &slotMethod)

static bool	disconnect (const QObject sender, const QString &signalMethod, const QObject receiver, const QString &slotMethod)

static bool	disconnect (const QObject sender, const QString &signalMethod, const QString &location, const QObject receiver, const QString &slotMethod)

static bool	disconnect (const QObject sender, std::nullptr_t, const QObject receiver, std::nullptr_t)

template<class Sender , class SignalClass , class... SignalArgs, class Receiver , class SlotClass , class... SlotArgs, class SlotReturn >
static bool	disconnect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver receiver, SlotReturn (SlotClass::slotMethod)(SlotArgs...))

template<class Sender , class SignalClass , class... SignalArgs, class Receiver >
static bool	disconnect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver *receiver, std::nullptr_t slotMethod=nullptr)

template<class Sender , class SignalClass , class... SignalArgs, class Receiver , class T >
static bool	disconnect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver *receiver, T slotMethod)

static QMetaObject &	staticMetaObject ()

static QString	tr (const char text, const char comment=nullptr, std::optional< int > numArg=std::optional< int >())

Related Functions inherited from QObject
T	qobject_cast (QObject *object)

	QObjectList

Detailed Description

The QTimeLine class provides a timeline for controlling animations. This class is commonly used to animate a GUI control by calling a slot periodically.

You can construct a timeline by passing its duration in milliseconds to the QTimeLine constructor. The timeline duration describes for how long the animation will run. Then you set a suitable frame range by calling setFrameRange(). Finally connect the frameChanged() signal to a suitable slot in the widget you wish to animate (e.g., setValue() in QProgressBar). When you proceed to calling start(), QTimeLine will enter Running state, and start emitting frameChanged() at regular intervals, causing your widget's connected property's value to grow from the lower end to the upper and of your frame range, at a steady rate. You can specify the update interval by calling setUpdateInterval(). When done, QTimeLine enters NotRunning state, and emits finished().

progressBar = new QProgressBar(this);
progressBar->setRange(0, 100);
 
// Construct a 1 second timeline with a frame range of 0 - 100
QTimeLine *timeLine = new QTimeLine(1000, this);
timeLine->setFrameRange(0, 100);
 
connect(timeLine, &QTimeLine::frameChanged, progressBar, &QProgressBar::setValue);
 
// Clicking the push button will start the progress bar animation
pushButton = new QPushButton(tr("Start animation"), this);
connect(pushButton, &QPushButton::clicked, timeLine, &QTimeLine::start) ;

You can also use QTimeLine with the Graphics View System for animations. The QGraphicsItemAnimation class implements animation of QGraphicsItems with a timeline.

By default the timeline runs once, from the beginning and towards the end, upon which you must call start() again to restart from the beginning. To make the timeline loop, you can call setLoopCount(), passing the number of times the timeline should run before finishing. The direction can also be changed, causing the timeline to run backward, by calling setDirection(). You can also pause and unpause the timeline while it is running by calling setPaused(). For interactive control, the setCurrentTime() function is provided, which sets the time position of the time line directly. Although most useful in NotRunning state, (e.g., connected to a valueChanged() signal in a QSlider,) this method can be called at any time.

The frame interface is useful for standard widgets, but QTimeLine can be used to control any type of animation. The heart of QTimeLine lies in the valueForTime() function, which generates a value between 0 and 1 for a given time. This value is typically used to describe the steps of an animation, where 0 is the first step of an animation, and 1 is the last step. When running, QTimeLine generates values between 0 and 1 by calling valueForTime() and emitting valueChanged(). By default, valueForTime() applies an interpolation algorithm to generate these value. You can choose from a set of predefined timeline algorithms by calling setCurveShape().

By default QTimeLine uses the EaseInOut curve shape. This provides a value which grows slowly, then grows steadily, and finally grows slowly. For a custom timeline, you can reimplement valueForTime(), in which case QTimeLine's curveShape property is ignored.

See also: QProgressBar, QProgressDialog, QGraphicsItemAnimation

Member Enumeration Documentation

enum QTimeLine::CurveShape

This enum describes the default shape of QTimeLine's value curve. The default, shape is EaseInOutCurve. The curve defines the relation between the value and the timeline.

Constant	Value	Description
`QTimeLine::EaseInCurve`	`0`	The value starts growing slowly, then increases in speed.
`QTimeLine::EaseOutCurve`	`1`	The value starts growing steadily, then ends slowly.
`QTimeLine::EaseInOutCurve`	`2`	The value starts growing slowly, then runs steadily, then grows slowly again.
`QTimeLine::LinearCurve`	`3`	The value grows linearly (e.g., if the duration is 1000 ms, the value at time 500 ms is 0.5).
`QTimeLine::SineCurve`	`4`	The value grows sinusoidally.
`QTimeLine::CosineCurve`	`5`	The value grows cosinusoidally.

See also: setCurveShape()

enum QTimeLine::Direction

This enum describes the direction of the timeline when in Running state.

Constant	Value	Description
`QTimeLine::Forward`	`0`	The current time of the timeline increases with time (i.e., moves from 0 and towards the end / duration).
`QTimeLine::Backward`	`1`	The current time of the timeline decreases with time (i.e., moves from the end / duration and towards 0).

See also: setDirection()

enum QTimeLine::State

This enum describes the state of the timeline.

Constant	Value	Description
`QTimeLine::NotRunning`	`0`	The timeline is not running. This is the initial state of QTimeLine, and the state QTimeLine reenters when finished. The current time, frame and value remain unchanged until either setCurrentTime() is called, or the timeline is started by calling start().
`QTimeLine::Paused`	`1`	The timeline is paused (i.e., temporarily suspended). Calling setPaused(false) will resume timeline activity.
`QTimeLine::Running`	`2`	The timeline is running. While control is in the event loop, QTimeLine will update its current time at regular intervals, emitting valueChanged() and frameChanged() when appropriate.

See also: state(), stateChanged()

Constructor & Destructor Documentation

QTimeLine::QTimeLine	(	int	duration = `1000`,
		QObject *	parent = `nullptr`
	)

explicit

Constructs a timeline with a duration of duration milliseconds. The parent is passed to the QObject constructor. The default duration is 1000 milliseconds.

QTimeLine::~QTimeLine ( )

virtual

Destroys the timeline.

Method Documentation

int QTimeLine::currentFrame ( ) const

Returns the frame corresponding to the current time.

See also: currentTime(), frameForTime(), setFrameRange()

int QTimeLine::currentTime ( ) const

Returns the value of the property.

qreal QTimeLine::currentValue ( ) const

Returns the value corresponding to the current time.

See also: valueForTime(), currentFrame()

CurveShape QTimeLine::curveShape ( ) const

Returns the value of the property.

Direction QTimeLine::direction ( ) const

Returns the value of the property.

int QTimeLine::duration ( ) const

Returns the value of the property.

QEasingCurve QTimeLine::easingCurve ( ) const

Returns the value of the property.

int QTimeLine::endFrame ( ) const

Returns the end frame, which is the frame corresponding to the end of the timeline (i.e., the frame for which the current value is 1).

See also: setEndFrame(), setFrameRange()

void QTimeLine::finished ( )

signal

This signal is emitted when QTimeLine finishes (i.e., reaches the end of its time line), and does not loop.

void QTimeLine::frameChanged ( int frame )

signal

QTimeLine emits this signal at regular intervals when in Running state, but only if the current frame changes. frame is the current frame number.

See also: QTimeLine::setFrameRange(), QTimeLine::updateInterval

int QTimeLine::frameForTime ( int msec ) const

Returns the frame corresponding to the time msec. This value is calculated using a linear interpolation of the start and end frame, based on the value returned by valueForTime().

See also: valueForTime(), setFrameRange()

int QTimeLine::loopCount ( ) const

Returns the value of the property.

void QTimeLine::resume ( )

slot

Resumes the timeline from the current time. QTimeLine will reenter Running state, and once it enters the event loop, it will update its current time, frame and value at regular intervals.

In contrast to start(), this function does not restart the timeline before it resumes.

See also: start(), updateInterval(), frameChanged(), valueChanged()

void QTimeLine::setCurrentTime ( int msec )

slot

Sets the value of the property to msec.

void QTimeLine::setCurveShape ( CurveShape shape )

Sets the value of the property to shape.

void QTimeLine::setDirection ( Direction direction )

Sets the value of the property to direction.

void QTimeLine::setDuration ( int duration )

Sets the value of the property to duration.

void QTimeLine::setEasingCurve ( const QEasingCurve & curve )

Sets the value of the property to curve.

void QTimeLine::setEndFrame ( int frame )

Sets the end frame, which is the frame corresponding to the end of the timeline (i.e., the frame for which the current value is 1), to frame.

See also: endFrame(), startFrame(), setFrameRange()

void QTimeLine::setFrameRange	(	int	startFrame,
		int	endFrame
	)

Sets the timeline's frame counter to start at startFrame, and end and endFrame. For each time value, QTimeLine will find the corresponding frame when you call currentFrame() or frameForTime() by interpolating, using the return value of valueForTime().

When in Running state, QTimeLine also emits the frameChanged() signal when the frame changes.

See also: startFrame(), endFrame(), start(), currentFrame()

void QTimeLine::setLoopCount ( int count )

Sets the value of the property to count.

void QTimeLine::setPaused ( bool paused )

slot

If paused is true, the timeline is paused, causing QTimeLine to enter Paused state. No updates will be signaled until either start() or setPaused(false) is called. If paused is false, the timeline is resumed and continues where it left.

See also: state(), start()

void QTimeLine::setStartFrame ( int frame )

Sets the start frame, which is the frame corresponding to the start of the timeline (i.e., the frame for which the current value is 0), to frame.

See also: startFrame(), endFrame(), setFrameRange()

void QTimeLine::setUpdateInterval ( int interval )

Sets the value of the property to interval.

void QTimeLine::start ( )

slot

Starts the timeline. QTimeLine will enter Running state, and once it enters the event loop, it will update its current time, frame and value at regular intervals. The default interval is 40 ms (i.e., 25 times per second). You can change the update interval by calling setUpdateInterval().

The timeline will start from position 0, or the end if going backward. If you want to resume a stopped timeline without restarting, you can call resume() instead.

See also: resume(), updateInterval(), frameChanged(), valueChanged()

int QTimeLine::startFrame ( ) const

Returns the start frame, which is the frame corresponding to the start of the timeline (i.e., the frame for which the current value is 0).

See also: setStartFrame(), setFrameRange()

State QTimeLine::state ( ) const

Returns the state of the timeline.

See also: start(), setPaused(), stop()

void QTimeLine::stateChanged ( QTimeLine::State newState )

signal

This signal is emitted whenever QTimeLine's state changes. The new state is newState.

void QTimeLine::stop ( )

slot

Stops the timeline, causing QTimeLine to enter NotRunning state.

See also: start()

void QTimeLine::timerEvent ( QTimerEvent * event )

overrideprotectedvirtual

Reimplemented from QObject::timerEvent()

void QTimeLine::toggleDirection ( )

slot

Toggles the direction of the timeline. If the direction was Forward, it becomes Backward, and vice versa.

See also: setDirection()

int QTimeLine::updateInterval ( ) const

Returns the value of the property.

void QTimeLine::valueChanged ( qreal value )

signal

QTimeLine emits this signal at regular intervals when in Running state, but only if the current value changes. The passed parameter of value is the current value and a number between 0.0 and 1.0.

See also: QTimeLine::setDuration(), QTimeLine::valueForTime(), QTimeLine::updateInterval

qreal QTimeLine::valueForTime ( int msec ) const

virtual

Returns the timeline value for the time msec. The returned value, which varies depending on the curve shape, is always between 0 and 1. If msec is 0, the default implementation always returns 0.

Reimplement this function to provide a custom curve shape for your timeline.

See also: CurveShape, frameForTime()

Property Documentation

QTimeLine::currentTime

This property holds the current time of the time line.

When QTimeLine is in Running state, this value is updated continuously as a function of the duration and direction of the timeline. Otherwise, it is value that was current when stop() was called last, or the value set by setCurrentTime().

By default, this property contains a value of 0.

Properties	Class Methods
read	currentTime
write	setCurrentTime

QTimeLine::curveShape

This property holds the shape of the timeline curve.

The curve shape describes the relation between the time and value for the base implementation of valueForTime().

If you have reimplemented valueForTime(), this value is ignored.

By default, this property is set to EaseInOutCurve.

See also: valueForTime()

Properties	Class Methods
read	curveShape
write	setCurveShape

QTimeLine::direction

This property holds the direction of the timeline when QTimeLine is in Running state. This direction indicates whether the time moves from 0 towards the timeline duration, or from the value of the duration and towards 0 after start() has been called.

By default, this property is set to Forward.

Properties	Class Methods
read	direction
write	setDirection

QTimeLine::duration

This property holds the total duration of the timeline in milliseconds. Changing the duration does not cause the current time to be reset to zero or the new duration. You also need to call setCurrentTime() with the desired value.

By default this value is 1000 which is 1 second. It can be changed by either passing a duration to the QTimeLine constructor or by calling setDuration(). The duration must be larger than 0.

Properties	Class Methods
read	duration
write	setDuration

QTimeLine::easingCurve

Specifies the easing curve that the timeline will use. If both easing curve and curveShape are set, the last set property will override the previous one. (If valueForTime() is reimplemented it will override both)

Properties	Class Methods
read	easingCurve
write	setEasingCurve

QTimeLine::loopCount

This property holds the number of times the timeline should loop before it is finished. A loop count of 0 means the timeline will loop forever. By default, this property contains a value of 1.

Properties	Class Methods
read	loopCount
write	setLoopCount

QTimeLine::updateInterval

This property holds the time in milliseconds between each time QTimeLine updates its current time. When updating the current time, QTimeLine will emit valueChanged() if the current value changed, and frameChanged() if the frame changed. By default, the interval is 40 ms, which corresponds to a rate of 25 updates per second.

Properties	Class Methods
read	updateInterval
write	setUpdateInterval

Public Types

Public Signals

Public Slots

Public Methods

Protected Methods

Properties

Additional Inherited Members

Detailed Description

Member Enumeration Documentation

Constructor & Destructor Documentation

Method Documentation

Property Documentation