QMovie Class

The QMovie class is a convenience class for playing movies with QImageReader. More...

Header:	#include <QMovie>
CMake:	find_package(Qt6 REQUIRED COMPONENTS Gui) target_link_libraries(mytarget PRIVATE Qt6::Gui)
qmake:	QT += gui
Inherits:	QObject

List of all members, including inherited members

Public Types

enum	CacheMode { CacheNone, CacheAll }
enum	MovieState { NotRunning, Paused, Running }

Properties

cacheMode : CacheMode
speed : int

Public Functions

	QMovie(const QString &fileName, const QByteArray &format = QByteArray(), QObject *parent = nullptr)
	QMovie(QIODevice *device, const QByteArray &format = QByteArray(), QObject *parent = nullptr)
	QMovie(QObject *parent = nullptr)
virtual	~QMovie()
QColor	backgroundColor() const
QMovie::CacheMode	cacheMode() const
int	currentFrameNumber() const
QImage	currentImage() const
QPixmap	currentPixmap() const
QIODevice *	device() const
QString	fileName() const
QByteArray	format() const
int	frameCount() const
QRect	frameRect() const
bool	isValid() const
bool	jumpToFrame(int frameNumber)
QImageReader::ImageReaderError	lastError() const
QString	lastErrorString() const
int	loopCount() const
int	nextFrameDelay() const
QSize	scaledSize()
void	setBackgroundColor(const QColor &color)
void	setCacheMode(QMovie::CacheMode mode)
void	setDevice(QIODevice *device)
void	setFileName(const QString &fileName)
void	setFormat(const QByteArray &format)
void	setScaledSize(const QSize &size)
int	speed() const
QMovie::MovieState	state() const

Public Slots

bool	jumpToNextFrame()
void	setPaused(bool paused)
void	setSpeed(int percentSpeed)
void	start()
void	stop()

Signals

void	error(QImageReader::ImageReaderError error)
void	finished()
void	frameChanged(int frameNumber)
void	resized(const QSize &size)
void	started()
void	stateChanged(QMovie::MovieState state)
void	updated(const QRect &rect)

Static Public Members

QList<QByteArray> supportedFormats()

Detailed Description

This class is used to show simple animations without sound.

First, create a QMovie object by passing either the name of a file or a pointer to a QIODevice containing an animated image format to QMovie's constructor. You can call isValid() to check if the image data is valid, before starting the movie. To start the movie, call start(). QMovie will enter Running state, and emit started() and stateChanged(). To get the current state of the movie, call state().

To display the movie in your application, you can pass your QMovie object to QLabel::setMovie(). Example:

QLabel label;
QMovie *movie = new QMovie("animations/fire.gif");

label.setMovie(movie);
movie->start();

Whenever a new frame is available in the movie, QMovie will emit updated(). If the size of the frame changes, resized() is emitted. You can call currentImage() or currentPixmap() to get a copy of the current frame. When the movie is done, QMovie emits finished(). If any error occurs during playback (i.e, the image file is corrupt), QMovie will emit error().

You can control the speed of the movie playback by calling setSpeed(), which takes the percentage of the original speed as an argument. Pause the movie by calling setPaused(true). QMovie will then enter Paused state and emit stateChanged(). If you call setPaused(false), QMovie will reenter Running state and start the movie again. To stop the movie, call stop().

Certain animation formats allow you to set the background color. You can call setBackgroundColor() to set the color, or backgroundColor() to retrieve the current background color.

currentFrameNumber() returns the sequence number of the current frame. The first frame in the animation has the sequence number 0. frameCount() returns the total number of frames in the animation, if the image format supports this. You can call loopCount() to get the number of times the movie should loop before finishing. nextFrameDelay() returns the number of milliseconds the current frame should be displayed.

QMovie can be instructed to cache frames of an animation by calling setCacheMode().

Call supportedFormats() for a list of formats that QMovie supports.

See also QLabel, QImageReader, and Movie Example.

Member Type Documentation

enum QMovie::CacheMode

This enum describes the different cache modes of QMovie.

Constant	Value	Description
`QMovie::CacheNone`	`0`	No frames are cached (the default).
`QMovie::CacheAll`	`1`	All frames are cached.

enum QMovie::MovieState

This enum describes the different states of QMovie.

Constant	Value	Description
`QMovie::NotRunning`	`0`	The movie is not running. This is QMovie's initial state, and the state it enters after stop() has been called or the movie is finished.
`QMovie::Paused`	`1`	The movie is paused, and QMovie stops emitting updated() or resized(). This state is entered after calling pause() or setPaused(true). The current frame number it kept, and the movie will continue with the next frame when unpause() or setPaused(false) is called.
`QMovie::Running`	`2`	The movie is running.

Property Documentation

`[bindable]` cacheMode : CacheMode

Note: This property supports QProperty bindings.

This property holds the movie's cache mode

Caching frames can be useful when the underlying animation format handler that QMovie relies on to decode the animation data does not support jumping to particular frames in the animation, or even "rewinding" the animation to the beginning (for looping). Furthermore, if the image data comes from a sequential device, it is not possible for the underlying animation handler to seek back to frames whose data has already been read (making looping altogether impossible).

To aid in such situations, a QMovie object can be instructed to cache the frames, at the added memory cost of keeping the frames in memory for the lifetime of the object.

By default, this property is set to CacheNone.

See also QMovie::CacheMode.

`[bindable]` speed : int

Note: This property supports QProperty bindings.

This property holds the movie's speed

The speed is measured in percentage of the original movie speed. The default speed is 100%. Example:

QMovie movie("racecar.gif");
movie.setSpeed(200); // 2x speed

Member Function Documentation

QMovie::QMovie(const QString &fileName, const QByteArray &format = QByteArray(), QObject **parent* = nullptr)

Constructs a QMovie object. QMovie will use read image data from fileName. If format is not empty, QMovie will use the image format format for decoding the image data. Otherwise, QMovie will attempt to guess the format.

The parent object is passed to QObject's constructor.

QMovie::QMovie(QIODevice **device, const QByteArray &format* = QByteArray(), QObject **parent* = nullptr)

Constructs a QMovie object. QMovie will use read image data from device, which it assumes is open and readable. If format is not empty, QMovie will use the image format format for decoding the image data. Otherwise, QMovie will attempt to guess the format.

The parent object is passed to QObject's constructor.

QMovie::QMovie(QObject **parent* = nullptr)

Constructs a QMovie object, passing the parent object to QObject's constructor.

See also setFileName(), setDevice(), and setFormat().

`[signal]` void QMovie::error(QImageReader::ImageReaderError error)

This signal is emitted by QMovie when the error error occurred during playback. QMovie will stop the movie, and enter QMovie::NotRunning state.

See also lastError() and lastErrorString().

`[signal]` void QMovie::finished()

This signal is emitted when the movie has finished.

See also QMovie::stop().

`[signal]` void QMovie::frameChanged(int frameNumber)

This signal is emitted when the frame number has changed to frameNumber. You can call currentImage() or currentPixmap() to get a copy of the frame.

`[slot]` bool QMovie::jumpToNextFrame()

Jumps to the next frame. Returns true on success; otherwise returns false.

`[signal]` void QMovie::resized(const QSize &size)

This signal is emitted when the current frame has been resized to size. This effect is sometimes used in animations as an alternative to replacing the frame. You can call currentImage() or currentPixmap() to get a copy of the updated frame.

`[slot]` void QMovie::setPaused(bool paused)

If paused is true, QMovie will enter Paused state and emit stateChanged(Paused); otherwise it will enter Running state and emit stateChanged(Running).

See also state().

`[slot]` void QMovie::start()

Starts the movie. QMovie will enter Running state, and start emitting updated() and resized() as the movie progresses.

If QMovie is in the Paused state, this function is equivalent to calling setPaused(false). If QMovie is already in the Running state, this function does nothing.

See also stop() and setPaused().

`[signal]` void QMovie::started()

This signal is emitted after QMovie::start() has been called, and QMovie has entered QMovie::Running state.

`[signal]` void QMovie::stateChanged(QMovie::MovieState state)

This signal is emitted every time the state of the movie changes. The new state is specified by state.

See also QMovie::state().

`[slot]` void QMovie::stop()

Stops the movie. QMovie enters NotRunning state, and stops emitting updated() and resized(). If start() is called again, the movie will restart from the beginning.

If QMovie is already in the NotRunning state, this function does nothing.

See also start() and setPaused().

`[signal]` void QMovie::updated(const QRect &rect)

This signal is emitted when the rect rect in the current frame has been updated. You can call currentImage() or currentPixmap() to get a copy of the updated frame.

`[virtual]` QMovie::~QMovie()

Destructs the QMovie object.

QColor QMovie::backgroundColor() const

Returns the background color of the movie. If no background color has been assigned, an invalid QColor is returned.

See also setBackgroundColor().

int QMovie::currentFrameNumber() const

Returns the sequence number of the current frame. The number of the first frame in the movie is 0.

QImage QMovie::currentImage() const

Returns the current frame as a QImage.

See also currentPixmap() and updated().

QPixmap QMovie::currentPixmap() const

Returns the current frame as a QPixmap.

See also currentImage() and updated().

QIODevice *QMovie::device() const

Returns the device QMovie reads image data from. If no device has currently been assigned, nullptr is returned.

See also setDevice() and fileName().

QString QMovie::fileName() const

Returns the name of the file that QMovie reads image data from. If no file name has been assigned, or if the assigned device is not a file, an empty QString is returned.

See also setFileName() and device().

QByteArray QMovie::format() const

Returns the format that QMovie uses when decoding image data. If no format has been assigned, an empty QByteArray() is returned.

See also setFormat().

int QMovie::frameCount() const

Returns the number of frames in the movie.

Certain animation formats do not support this feature, in which case 0 is returned.

QRect QMovie::frameRect() const

Returns the rect of the last frame. If no frame has yet been updated, an invalid QRect is returned.

See also currentImage() and currentPixmap().

bool QMovie::isValid() const

Returns true if the movie is valid (e.g., the image data is readable and the image format is supported); otherwise returns false.

For information about why the movie is not valid, see lastError().

bool QMovie::jumpToFrame(int frameNumber)

Jumps to frame number frameNumber. Returns true on success; otherwise returns false.

QImageReader::ImageReaderError QMovie::lastError() const

Returns the most recent error that occurred while attempting to read image data.

See also lastErrorString().

QString QMovie::lastErrorString() const

Returns a human-readable representation of the most recent error that occurred while attempting to read image data.

See also lastError().

int QMovie::loopCount() const

Returns the number of times the movie will loop before it finishes. If the movie will only play once (no looping), loopCount returns 0. If the movie loops forever, loopCount returns -1.

Note that, if the image data comes from a sequential device (e.g. a socket), QMovie can only loop the movie if the cacheMode is set to QMovie::CacheAll.

int QMovie::nextFrameDelay() const

Returns the number of milliseconds QMovie will wait before updating the next frame in the animation.

QSize QMovie::scaledSize()

Returns the scaled size of frames.

See also setScaledSize() and QImageReader::scaledSize().

void QMovie::setBackgroundColor(const QColor &color)

For image formats that support it, this function sets the background color to color.

See also backgroundColor().

void QMovie::setDevice(QIODevice **device*)

Sets the current device to device. QMovie will read image data from this device when the movie is running.

See also device() and setFormat().

void QMovie::setFileName(const QString &fileName)

Sets the name of the file that QMovie reads image data from, to fileName.

See also fileName(), setDevice(), and setFormat().

void QMovie::setFormat(const QByteArray &format)

Sets the format that QMovie will use when decoding image data, to format. By default, QMovie will attempt to guess the format of the image data.

You can call supportedFormats() for the full list of formats QMovie supports.

See also format() and QImageReader::supportedImageFormats().

void QMovie::setScaledSize(const QSize &size)

Sets the scaled frame size to size.

See also scaledSize() and QImageReader::setScaledSize().

QMovie::MovieState QMovie::state() const

Returns the current state of QMovie.

See also MovieState and stateChanged().

`[static]` QList<QByteArray> QMovie::supportedFormats()

Returns the list of image formats supported by QMovie.

See also QImageReader::supportedImageFormats().

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