QAbstractAnimation Class

The QAbstractAnimation class is the base of all animations. More...

Header:	#include <QAbstractAnimation>
qmake:	QT += core
Since:	Qt 4.6
Inherits:	QObject
Inherited By:	QAnimationGroup, QPauseAnimation, and QVariantAnimation

This class was introduced in Qt 4.6.

• List of all members, including inherited members

Public Types

enum	DeletionPolicy { KeepWhenStopped, DeleteWhenStopped }
enum	Direction { Forward, Backward }
enum	State { Stopped, Paused, Running }

Properties

currentLoop : const int currentTime : int direction : Direction

duration : const int loopCount : int state : const State

Public Functions

	QAbstractAnimation(QObject *parent = nullptr)
virtual	~QAbstractAnimation()
int	currentLoop() const
int	currentLoopTime() const
int	currentTime() const
QAbstractAnimation::Direction	direction() const
virtual int	duration() const = 0
QAnimationGroup *	group() const
int	loopCount() const
void	setDirection(QAbstractAnimation::Direction direction)
void	setLoopCount(int loopCount)
QAbstractAnimation::State	state() const
int	totalDuration() const

Public Slots

void	pause()
void	resume()
void	setCurrentTime(int msecs)
void	setPaused(bool paused)
void	start(QAbstractAnimation::DeletionPolicy policy = KeepWhenStopped)
void	stop()

Signals

void	currentLoopChanged(int currentLoop)
void	directionChanged(QAbstractAnimation::Direction newDirection)
void	finished()
void	stateChanged(QAbstractAnimation::State newState, QAbstractAnimation::State oldState)

Protected Functions

virtual void	updateCurrentTime(int currentTime) = 0
virtual void	updateDirection(QAbstractAnimation::Direction direction)
virtual void	updateState(QAbstractAnimation::State newState, QAbstractAnimation::State oldState)

Reimplemented Protected Functions

virtual bool

event(QEvent *event) override

Detailed Description

The class defines the functions for the functionality shared by all animations. By inheriting this class, you can create custom animations that plug into the rest of the animation framework.

The progress of an animation is given by its current time (currentLoopTime()), which is measured in milliseconds from the start of the animation (0) to its end (duration()). The value is updated automatically while the animation is running. It can also be set directly with setCurrentTime().

At any point an animation is in one of three states: Running, Stopped, or Paused--as defined by the State enum. The current state can be changed by calling start(), stop(), pause(), or resume(). An animation will always reset its current time when it is started. If paused, it will continue with the same current time when resumed. When an animation is stopped, it cannot be resumed, but will keep its current time (until started again). QAbstractAnimation will emit stateChanged() whenever its state changes.

An animation can loop any number of times by setting the loopCount property. When an animation's current time reaches its duration(), it will reset the current time and keep running. A loop count of 1 (the default value) means that the animation will run one time. Note that a duration of -1 means that the animation will run until stopped; the current time will increase indefinitely. When the current time equals duration() and the animation is in its final loop, the Stopped state is entered, and the finished() signal is emitted.

QAbstractAnimation provides pure virtual functions used by subclasses to track the progress of the animation: duration() and updateCurrentTime(). The duration() function lets you report a duration for the animation (as discussed above). The animation framework calls updateCurrentTime() when current time has changed. By reimplementing this function, you can track the animation progress. Note that neither the interval between calls nor the number of calls to this function are defined; though, it will normally be 60 updates per second.

By reimplementing updateState(), you can track the animation's state changes, which is particularly useful for animations that are not driven by time.

See also QVariantAnimation, QPropertyAnimation, QAnimationGroup, and The Animation Framework.

Member Type Documentation

enum QAbstractAnimation::DeletionPolicy

Constant	Value	Description
QAbstractAnimation::KeepWhenStopped	0	The animation will not be deleted when stopped.
QAbstractAnimation::DeleteWhenStopped	1	The animation will be automatically deleted when stopped.

enum QAbstractAnimation::Direction

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

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

See also direction.

enum QAbstractAnimation::State

This enum describes the state of the animation.

Constant	Value	Description
QAbstractAnimation::Stopped	0	The animation is not running. This is the initial state of QAbstractAnimation, and the state QAbstractAnimation reenters when finished. The current time remain unchanged until either setCurrentTime() is called, or the animation is started by calling start().
QAbstractAnimation::Paused	1	The animation is paused (i.e., temporarily suspended). Calling resume() will resume animation activity.
QAbstractAnimation::Running	2	The animation is running. While control is in the event loop, QAbstractAnimation will update its current time at regular intervals, calling updateCurrentTime() when appropriate.

See also state() and stateChanged().

Member Function Documentation

QAbstractAnimation::QAbstractAnimation(QObject *parent = nullptr)

Constructs the QAbstractAnimation base class, and passes parent to QObject's constructor.

See also QVariantAnimation and QAnimationGroup.

[signal] void QAbstractAnimation::currentLoopChanged(int currentLoop)

QAbstractAnimation emits this signal whenever the current loop changes. currentLoop is the current loop.

Note: Notifier signal for property currentLoop.

See also currentLoop() and loopCount().

[signal] void QAbstractAnimation::directionChanged(QAbstractAnimation::Direction newDirection)

QAbstractAnimation emits this signal whenever the direction has been changed. newDirection is the new direction.

Note: Notifier signal for property direction.

See also direction.

[signal] void QAbstractAnimation::finished()

QAbstractAnimation emits this signal after the animation has stopped and has reached the end.

This signal is emitted after stateChanged().

See also stateChanged().

[slot] void QAbstractAnimation::pause()

Pauses the animation. When the animation is paused, state() returns Paused. The value of currentTime will remain unchanged until resume() or start() is called. If you want to continue from the current time, call resume().

See also start(), state(), and resume().

[slot] void QAbstractAnimation::resume()

Resumes the animation after it was paused. When the animation is resumed, it emits the resumed() and stateChanged() signals. The currenttime is not changed.

See also start(), pause(), and state().

[slot] void QAbstractAnimation::setPaused(bool paused)

If paused is true, the animation is paused. If paused is false, the animation is resumed.

See also state(), pause(), and resume().

[slot] void QAbstractAnimation::start(QAbstractAnimation::DeletionPolicy policy = KeepWhenStopped)

Starts the animation. The policy argument says whether or not the animation should be deleted when it's done. When the animation starts, the stateChanged() signal is emitted, and state() returns Running. When control reaches the event loop, the animation will run by itself, periodically calling updateCurrentTime() as the animation progresses.

If the animation is currently stopped or has already reached the end, calling start() will rewind the animation and start again from the beginning. When the animation reaches the end, the animation will either stop, or if the loop level is more than 1, it will rewind and continue from the beginning.

If the animation is already running, this function does nothing.

See also stop() and state().

[signal] void QAbstractAnimation::stateChanged(QAbstractAnimation::State newState, QAbstractAnimation::State oldState)

QAbstractAnimation emits this signal whenever the state of the animation has changed from oldState to newState. This signal is emitted after the virtual updateState() function is called.

Note: Notifier signal for property state.

See also updateState().

[slot] void QAbstractAnimation::stop()

Stops the animation. When the animation is stopped, it emits the stateChanged() signal, and state() returns Stopped. The current time is not changed.

If the animation stops by itself after reaching the end (i.e., currentLoopTime() == duration() and currentLoop() > loopCount() - 1), the finished() signal is emitted.

See also start() and state().

[virtual] QAbstractAnimation::~QAbstractAnimation()

Stops the animation if it's running, then destroys the QAbstractAnimation. If the animation is part of a QAnimationGroup, it is automatically removed before it's destroyed.

int QAbstractAnimation::currentLoopTime() const

Returns the current time inside the current loop. It can go from 0 to duration().

See also duration() and currentTime.

[pure virtual] int QAbstractAnimation::duration() const

This pure virtual function returns the duration of the animation, and defines for how long QAbstractAnimation should update the current time. This duration is local, and does not include the loop count.

A return value of -1 indicates that the animation has no defined duration; the animation should run forever until stopped. This is useful for animations that are not time driven, or where you cannot easily predict its duration (e.g., event driven audio playback in a game).

If the animation is a parallel QAnimationGroup, the duration will be the longest duration of all its animations. If the animation is a sequential QAnimationGroup, the duration will be the sum of the duration of all its animations.

Note: Getter function for property duration.

See also loopCount.

[override virtual protected] bool QAbstractAnimation::event(QEvent *event)

Reimplements: QObject::event(QEvent *e).

QAnimationGroup *QAbstractAnimation::group() const

If this animation is part of a QAnimationGroup, this function returns a pointer to the group; otherwise, it returns nullptr.

See also QAnimationGroup::addAnimation().

int QAbstractAnimation::totalDuration() const

Returns the total and effective duration of the animation, including the loop count.

See also duration() and currentTime.

[pure virtual protected] void QAbstractAnimation::updateCurrentTime(int currentTime)

This pure virtual function is called every time the animation's currentTime changes.

See also updateState().

[virtual protected] void QAbstractAnimation::updateDirection(QAbstractAnimation::Direction direction)

This virtual function is called by QAbstractAnimation when the direction of the animation is changed. The direction argument is the new direction.

See also setDirection() and direction().

[virtual protected] void QAbstractAnimation::updateState(QAbstractAnimation::State newState, QAbstractAnimation::State oldState)

This virtual function is called by QAbstractAnimation when the state of the animation is changed from oldState to newState.

See also start(), stop(), pause(), and resume().