QImageCapture Class

The QImageCapture class is used for the recording of media content. More...

Header:	#include <QImageCapture>
CMake:	find_package(Qt6 COMPONENTS Multimedia REQUIRED) target_link_libraries(mytarget PRIVATE Qt6::Multimedia)
qmake:	QT += multimedia
Inherits:	QObject

• List of all members, including inherited members

Public Types

enum	Error { NoError, NotReadyError, ResourceError, OutOfSpaceError, NotSupportedFeatureError, FormatError }
enum	Quality { VeryLowQuality, LowQuality, NormalQuality, HighQuality, VeryHighQuality }

Properties

• fileFormat : const FileFormat
• metaData : QMediaMetaData
• quality : const Quality
• readyForCapture : const bool

Public Functions

	QImageCapture(QObject *parent = nullptr)
virtual	~QImageCapture()
void	addMetaData(const QMediaMetaData &metaData)
QMediaCaptureSession *	captureSession() const
QImageCapture::Error	error() const
QString	errorString() const
QImageCapture::FileFormat	fileFormat() const
bool	isAvailable() const
bool	isReadyForCapture() const
QMediaMetaData	metaData() const
QImageCapture::Quality	quality() const
QSize	resolution() const
void	setFileFormat(QImageCapture::FileFormat format)
void	setMetaData(const QMediaMetaData &metaData)
void	setQuality(QImageCapture::Quality quality)
void	setResolution(const QSize &resolution)
void	setResolution(int width, int height)

Public Slots

int	capture()
int	captureToFile(const QString &file = QString())

Signals

void	errorChanged()
void	errorOccurred(int id, QImageCapture::Error error, const QString &errorString)
void	fileFormatChanged()
void	imageAvailable(int id, const QVideoFrame &frame)
void	imageCaptured(int id, const QImage &preview)
void	imageExposed(int id)
void	imageSaved(int id, const QString &fileName)
void	metaDataChanged()
void	qualityChanged()
void	readyForCaptureChanged(bool ready)

Detailed Description

The QImageCapture class is a high level images recording class. It's not intended to be used alone but for accessing the media recording functions of other media objects, like QCamera.

QMediaCaptureSession captureSession;
camera = new QCamera;
captureSession.setCamera(camera);

QVideoWidget *preview = new QVideoWidget();
preview->show();
captureSession.setVideoOutput(preview);

imageCapture = new QImageCapture(camera);
captureSession.setImageCapture(imageCapture);

camera->start();
//on shutter button pressed
imageCapture->capture();

See also QCamera.

Member Type Documentation

enum QImageCapture::Error

Constant	Value	Description
QImageCapture::NoError	0	No Errors.
QImageCapture::NotReadyError	1	The service is not ready for capture yet.
QImageCapture::ResourceError	2	Device is not ready or not available.
QImageCapture::OutOfSpaceError	3	No space left on device.
QImageCapture::NotSupportedFeatureError	4	Device does not support stillimages capture.
QImageCapture::FormatError	5	Current format is not supported.

enum QImageCapture::Quality

Enumerates quality encoding levels.

Constant	Value
QImageCapture::VeryLowQuality	0
QImageCapture::LowQuality	1
QImageCapture::NormalQuality	2
QImageCapture::HighQuality	3
QImageCapture::VeryHighQuality	4

Member Function Documentation

QImageCapture::QImageCapture(QObject *parent = nullptr)

Constructs a image capture object, from a parent, that can capture individual still images produced by a camera.

You must connect both an image capture object and a QCamera to a capture session to capture images.

[slot] int QImageCapture::capture()

Capture the image and make it available as a QImage. This operation is asynchronous in majority of cases, followed by signals QImageCapture::imageExposed(), QImageCapture::imageCaptured() or QImageCapture::error().

QImageCapture::capture returns the capture Id parameter, used with imageExposed(), imageCaptured() and imageSaved() signals.

See also isReadyForCapture().

[slot] int QImageCapture::captureToFile(const QString &file = QString())

Capture the image and save it to file. This operation is asynchronous in majority of cases, followed by signals QImageCapture::imageExposed(), QImageCapture::imageCaptured(), QImageCapture::imageSaved() or QImageCapture::error().

If an empty file is passed, the camera back end chooses the default location and naming scheme for photos on the system, if only file name without full path is specified, the image will be saved to the default directory, with a full path reported with imageCaptured() and imageSaved() signals.

QCamera saves all the capture parameters like exposure settings or image processing parameters, so changes to camera parameters after capture() is called do not affect previous capture requests.

QImageCapture::capture returns the capture Id parameter, used with imageExposed(), imageCaptured() and imageSaved() signals.

See also isReadyForCapture().

[signal] void QImageCapture::errorOccurred(int id, QImageCapture::Error error, const QString &errorString)

Signals that the capture request id has failed with an error and errorString description.

[signal] void QImageCapture::imageAvailable(int id, const QVideoFrame &frame)

Signal emitted when QImageCapture::CaptureToBuffer is set and the frame with request id is available.

[signal] void QImageCapture::imageCaptured(int id, const QImage &preview)

Signal emitted when the frame with request id was captured, but not processed and saved yet. Frame preview can be displayed to user.

[signal] void QImageCapture::imageExposed(int id)

Signal emitted when the frame with request id was exposed.

[signal] void QImageCapture::imageSaved(int id, const QString &fileName)

Signal emitted when QImageCapture::CaptureToFile is set and the frame with request id was saved to fileName.

[signal] void QImageCapture::readyForCaptureChanged(bool ready)

Signals that a camera's ready for capture state has changed.

Note: Notifier signal for property readyForCapture.

[virtual] QImageCapture::~QImageCapture()

Destroys images capture object.

void QImageCapture::addMetaData(const QMediaMetaData &metaData)

Adds additional metaData to any existing meta data, that is embedded into the captured image.

QMediaCaptureSession *QImageCapture::captureSession() const

Returns the capture session this camera is connected to, or a nullptr if the camera is not connected to a capture session.

Use QMediaCaptureSession::setImageCapture() to connect the image capture to a session.

QImageCapture::Error QImageCapture::error() const

Returns the current error state.

Note: Getter function for property error.

See also errorString().

QString QImageCapture::errorString() const

Returns a string describing the current error state.

Note: Getter function for property errorString.

See also error().

bool QImageCapture::isAvailable() const

Returns true if the images capture service ready to use.

QSize QImageCapture::resolution() const

Returns the resolution of the encoded image.

See also setResolution().

void QImageCapture::setFileFormat(QImageCapture::FileFormat format)

Sets the image format.

See also fileFormat().

void QImageCapture::setMetaData(const QMediaMetaData &metaData)

Replaces any existing meta data, to be embedded into the captured image, with a set of metaData.

Note: Setter function for property metaData.

See also metaData().

void QImageCapture::setQuality(QImageCapture::Quality quality)

Sets the image encoding quality.

See also quality().

void QImageCapture::setResolution(const QSize &resolution)

Sets the resolution of the encoded image.

An empty QSize indicates the encoder should make an optimal choice based on what is available from the image source and the limitations of the codec.

See also resolution().

void QImageCapture::setResolution(int width, int height)

Sets the width and height of the resolution of the encoded image.

This is an overloaded function.