...
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, SIGNAL(frameChanged(int)), progressBar, SLOT(setValue(int)));

// Clicking the push button will start the progress bar animation
pushButton = new QPushButton(tr("Start animation"), this);
connect(pushButton, SIGNAL(clicked()), timeLine, SLOT(start()));
...

Member Function Documentation

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

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

[signal] void QTimeLine::finished()

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

Note: This is a private signal. It can be used in signal connections but cannot be emitted by the user.

[signal] void QTimeLine::frameChanged(int frame)

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

Note: This is a private signal. It can be used in signal connections but cannot be emitted by the user.

See also QTimeLine::setFrameRange() and QTimeLine::updateInterval.

[slot] void QTimeLine::resume()

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(), and valueChanged().

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

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() and start().

[slot] void QTimeLine::start()

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(), and valueChanged().

[signal] void QTimeLine::stateChanged(QTimeLine::State newState)

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

Note: This is a private signal. It can be used in signal connections but cannot be emitted by the user.

[slot] void QTimeLine::stop()

Stops the timeline, causing QTimeLine to enter NotRunning state.

See also start().

[slot] void QTimeLine::toggleDirection()

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

See also setDirection().

[signal] void QTimeLine::valueChanged(qreal value)

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

Note: This is a private signal. It can be used in signal connections but cannot be emitted by the user.

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

[virtual] QTimeLine::~QTimeLine()

Destroys the timeline.

int QTimeLine::currentFrame() const

Returns the frame corresponding to the current time.

See also currentTime(), frameForTime(), and setFrameRange().

qreal QTimeLine::currentValue() const

Returns the value corresponding to the current time.

See also valueForTime() and currentFrame().

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() and setFrameRange().

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() and setFrameRange().

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(), and 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(), and currentFrame().

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(), and setFrameRange().

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() and setFrameRange().

QTimeLine::State QTimeLine::state() const

Returns the state of the timeline.

See also start(), setPaused(), and stop().

[override virtual protected] void QTimeLine::timerEvent(QTimerEvent *event)

Reimplements: QObject::timerEvent(QTimerEvent *event).

[virtual] qreal QTimeLine::valueForTime(int msec) const

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 and frameForTime().