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QCamera 类

QCamera 类提供系统摄像头设备的接口。 更多...

头： #include <QCamera>
CMake: find_package(Qt6 COMPONENTS Multimedia REQUIRED)
target_link_libraries(mytarget PRIVATE Qt6::Multimedia)
qmake: QT += multimedia
实例化： Camera
继承： QObject

公共类型

enum Error { NoError, CameraError }
enum ExposureMode { ExposureAuto, ExposureManual, ExposurePortrait, ExposureNight, ExposureSports, …, ExposureBarcode }
enum class Feature { ColorTemperature, ExposureCompensation, IsoSensitivity, ManualExposureTime, CustomFocusPoint, FocusDistance }
flags Features
enum FlashMode { FlashOff, FlashOn, FlashAuto }
enum FocusMode { FocusModeAuto, FocusModeAutoNear, FocusModeAutoFar, FocusModeHyperfocal, FocusModeInfinity, FocusModeManual }
enum TorchMode { TorchOff, TorchOn, TorchAuto }
enum WhiteBalanceMode { WhiteBalanceAuto, WhiteBalanceManual, WhiteBalanceSunlight, WhiteBalanceCloudy, WhiteBalanceShade, …, WhiteBalanceSunset }

特性

公共函数

  QCamera (QCameraDevice::Position position , QObject * parent = nullptr)
  QCamera (const QCameraDevice & cameraDevice , QObject * parent = nullptr)
  QCamera (QObject * parent = nullptr)
virtual ~QCamera ()
QCameraDevice cameraDevice () const
QCameraFormat cameraFormat () const
QMediaCaptureSession * captureSession () const
int colorTemperature () const
QPointF customFocusPoint () const
QCamera::Error error () const
QString errorString () const
float exposureCompensation () const
QCamera::ExposureMode exposureMode () const
float exposureTime () const
QCamera::FlashMode flashMode () const
float focusDistance () const
QCamera::FocusMode focusMode () const
QPointF focusPoint () const
bool isActive () const
bool isAvailable () const
bool isExposureModeSupported (QCamera::ExposureMode mode ) const
bool isFlashModeSupported (QCamera::FlashMode mode ) const
bool isFlashReady () const
bool isFocusModeSupported (QCamera::FocusMode mode ) const
bool isTorchModeSupported (QCamera::TorchMode mode ) const
bool isWhiteBalanceModeSupported (QCamera::WhiteBalanceMode mode ) const
int isoSensitivity () const
float manualExposureTime () const
int manualIsoSensitivity () const
float maximumExposureTime () const
int maximumIsoSensitivity () const
float maximumZoomFactor () const
float minimumExposureTime () const
int minimumIsoSensitivity () const
float minimumZoomFactor () const
void setCameraDevice (const QCameraDevice & cameraDevice )
void setCameraFormat (const QCameraFormat & format )
void setCustomFocusPoint (const QPointF & point )
void setFocusDistance (float d )
void setFocusMode (QCamera::FocusMode mode )
void setZoomFactor (float factor )
QCamera::Features supportedFeatures () const
QCamera::TorchMode torchMode () const
QCamera::WhiteBalanceMode whiteBalanceMode () const
float zoomFactor () const

公共槽

void setActive (bool active )
void setAutoExposureTime ()
void setAutoIsoSensitivity ()
void setColorTemperature (int colorTemperature )
void setExposureCompensation (float ev )
void setExposureMode (QCamera::ExposureMode mode )
void setFlashMode (QCamera::FlashMode mode )
void setManualExposureTime (float seconds )
void setManualIsoSensitivity (int iso )
void setTorchMode (QCamera::TorchMode mode )
void setWhiteBalanceMode (QCamera::WhiteBalanceMode mode )
void start ()
void stop ()
void zoomTo (float factor , float rate )

信号

void activeChanged (bool)
void cameraDeviceChanged ()
void cameraFormatChanged ()
void colorTemperatureChanged () const
void customFocusPointChanged ()
void errorChanged ()
void errorOccurred (QCamera::Error error , const QString & errorString )
void exposureCompensationChanged (float value )
void exposureModeChanged ()
void exposureTimeChanged (float speed )
void flashModeChanged ()
void flashReady (bool ready )
void focusDistanceChanged (float)
void focusPointChanged ()
void isoSensitivityChanged (int value )
void manualExposureTimeChanged (float speed )
void manualIsoSensitivityChanged (int)
void maximumZoomFactorChanged (float)
void minimumZoomFactorChanged (float)
void supportedFeaturesChanged ()
void torchModeChanged ()
void whiteBalanceModeChanged () const
void zoomFactorChanged (float)

详细描述

QCamera 可以用于 QMediaCaptureSession 为视频录制和图像获取。

可以使用 QCameraDevice 列表可用摄像头并选取要使用的摄像头。 

const QList<QCameraDevice> cameras = QMediaDevices::videoInputs();
for (const QCameraDevice &cameraDevice : cameras) {
    if (cameraDevice.description() == "mycamera")
        camera = new QCamera(cameraDevice);
}

On hardware that supports it, QCamera lets you adjust the focus and zoom. This also includes functionality such as a "Macro" mode for close up work (e.g. reading barcodes, or recognizing letters), or "touch to focus" - indicating an interesting area of the image for the hardware to attempt to focus on. 

camera->setFocusPointMode(QCamera::FocusModeManual);
camera->setCustomFocusPoint(QPointF(0.25f, 0.75f)); // A point near the bottom left, 25% away from the corner, near that shiny vase

minimumZoomFactor () 和 maximumZoomFactor () methods provide the range of supported zoom factors. The zoomTo () method allows changing the zoom factor. 

camera->setZoomFactor(3.0);

After capturing the raw data for a camera frame, the camera hardware and software performs various image processing tasks to produce the final image. This includes compensating for ambient light color, reducing noise, as well as making some other adjustments to the image.

You can control many of these processing steps through the Camera properties. For example, you can set the white balance (or color temperature) used for processing images: 

camera->setWhiteBalanceMode(QCamera::WhiteBalanceFluorescent);

For more information on image processing of camera frames, see 摄像头图像处理 .

见 摄像头概述 了解更多信息。

成员类型文档编制

enum QCamera:: Error

此枚举保持最后错误代码。

常量 值 描述
QCamera::NoError 0 没有出现错误。
QCamera::CameraError 1 有出现错误。

enum QCamera:: ExposureMode

常量 值 描述
QCamera::ExposureAuto 0 自动模式。
QCamera::ExposureManual 1 手动模式。
QCamera::ExposurePortrait 2 肖象曝光模式。
QCamera::ExposureNight 3 夜间模式。
QCamera::ExposureSports 4 亮点曝光模式。
QCamera::ExposureSnow 5 Snow exposure mode.
QCamera::ExposureBeach 6 Beach exposure mode.
QCamera::ExposureAction 7 Action mode. Since 5.5
QCamera::ExposureLandscape 8 Landscape mode. Since 5.5
QCamera::ExposureNightPortrait 9 Night portrait mode. Since 5.5
QCamera::ExposureTheatre 10 Theatre mode. Since 5.5
QCamera::ExposureSunset 11 Sunset mode. Since 5.5
QCamera::ExposureSteadyPhoto 12 Steady photo mode. Since 5.5
QCamera::ExposureFireworks 13 Fireworks mode. Since 5.5
QCamera::ExposureParty 14 Party mode. Since 5.5
QCamera::ExposureCandlelight 15 Candlelight mode. Since 5.5
QCamera::ExposureBarcode 16 Barcode mode. Since 5.5

enum class QCamera:: Feature
flags QCamera:: 特征

Describes a set of features supported by the camera. The returned value can be a combination of:

常量 值 描述
QCamera::Feature::ColorTemperature 0x1 The Camera supports setting a custom colorTemperature .
QCamera::Feature::ExposureCompensation 0x2 The Camera supports setting a custom exposureCompensation .
QCamera::Feature::IsoSensitivity 0x4 The Camera supports setting a custom isoSensitivity .
QCamera::Feature::ManualExposureTime 0x8 The Camera supports setting a manual exposure Time .
QCamera::Feature::CustomFocusPoint 0x10 The Camera supports setting a custom focus point .
QCamera::Feature::FocusDistance 0x20 The Camera supports setting the focusDistance 特性。

The Features type is a typedef for QFlags <Feature>. It stores an OR combination of Feature values.

enum QCamera:: FlashMode

常量 值 描述
QCamera::FlashOff 0 Flash is Off.
QCamera::FlashOn 1 Flash is On.
QCamera::FlashAuto 2 自动闪光。

enum QCamera:: FocusMode

常量 值 描述
QCamera::FocusModeAuto 0 Continuous auto focus mode.
QCamera::FocusModeAutoNear 1 Continuous auto focus mode on near objects.
QCamera::FocusModeAutoFar 2 Continuous auto focus mode on objects far away.
QCamera::FocusModeHyperfocal 3 Focus to hyperfocal distance, with the maximum depth of field achieved. All objects at distances from half of this distance out to infinity will be acceptably sharp.
QCamera::FocusModeInfinity 4 Focus strictly to infinity.
QCamera::FocusModeManual 5 Manual or fixed focus mode.

enum QCamera:: TorchMode

常量 值 描述
QCamera::TorchOff 0 Torch is Off.
QCamera::TorchOn 1 Torch is On.
QCamera::TorchAuto 2 Automatic torch.

enum QCamera:: WhiteBalanceMode

常量 值 描述
QCamera::WhiteBalanceAuto 0 Auto white balance mode.
QCamera::WhiteBalanceManual 1 Manual white balance. In this mode the white balance should be set with setColorTemperature ()
QCamera::WhiteBalanceSunlight 2 Sunlight white balance mode.
QCamera::WhiteBalanceCloudy 3 Cloudy white balance mode.
QCamera::WhiteBalanceShade 4 Shade white balance mode.
QCamera::WhiteBalanceTungsten 5 Tungsten (incandescent) white balance mode.
QCamera::WhiteBalanceFluorescent 6 Fluorescent white balance mode.
QCamera::WhiteBalanceFlash 7 Flash white balance mode.
QCamera::WhiteBalanceSunset 8 Sunset white balance mode.

特性文档编制

active : bool

Describes whether the camera is currently active.

访问函数：

bool isActive () const
void setActive (bool active )

通知程序信号：

void activeChanged (bool)

customFocusPoint : QPointF

This property represents the position of the custom focus point, in relative frame coordinates: QPointF (0,0) points to the left top frame point, QPointF (0.5,0.5) points to the frame center.

The custom focus point property is used only in FocusPointCustom focus mode.

You can check whether custom focus points are supported by querying supportedFeatures () with the Feature. CustomFocusPoint 标志。

访问函数：

QPointF customFocusPoint () const
void setCustomFocusPoint (const QPointF & point )

通知程序信号：

void customFocusPointChanged ()

exposureCompensation : float

Exposure compensation in EV units.

Exposure compensation property allows to adjust the automatically calculated exposure.

访问函数：

float exposureCompensation () const
void setExposureCompensation (float ev )

通知程序信号：

void exposureCompensationChanged (float value )

exposureMode : QCamera::ExposureMode

This property holds the exposure mode being used.

访问函数：

QCamera::ExposureMode exposureMode () const
void setExposureMode (QCamera::ExposureMode mode )

通知程序信号：

void exposureModeChanged ()

另请参阅 QCamera::isExposureModeSupported .

[read-only] exposureTime : const float

Camera's exposure time in seconds.

访问函数：

float exposureTime () const

通知程序信号：

void exposureTimeChanged (float speed )

另请参阅 minimumExposureTime (), maximumExposureTime ()，和 setManualExposureTime ().

flashMode : QCamera::FlashMode

This property holds the flash mode being used.

Enables a certain flash mode if the camera has a flash.

访问函数：

QCamera::FlashMode flashMode () const
void setFlashMode (QCamera::FlashMode mode )

通知程序信号：

void flashModeChanged ()

另请参阅 QCamera::FlashMode , QCamera::isFlashModeSupported ，和 QCamera::isFlashReady .

[read-only] flashReady : const bool

Indicates if the flash is charged and ready to use.

访问函数：

bool isFlashReady () const [见下文注意事项]

注意： 此函数可以被援引，通过元对象系统和从 QML。见 Q_INVOKABLE .

通知程序信号：

void flashReady (bool ready )

focusDistance : float

This property return an approximate focus distance of the camera. The value reported is between 0 and 1, 0 being the closest possible focus distance, 1 being as far away as possible. Note that 1 is often, but not always infinity.

Setting the focus distance will be ignored unless the focus mode is set to FocusModeManual .

访问函数：

float focusDistance () const
void setFocusDistance (float d )

通知程序信号：

void focusDistanceChanged (float)

focusMode : FocusMode

This property holds the current camera focus mode.

Sets up different focus modes for the camera. All auto focus modes will focus continuously. Locking the focus is possible by setting the focus mode to FocusModeManual . This will keep the current focus and stop any automatic focusing.

访问函数：

QCamera::FocusMode focusMode () const
void setFocusMode (QCamera::FocusMode mode )

另请参阅 isFocusModeSupported .

[read-only] isoSensitivity : const int

This property holds the sensor ISO sensitivity.

Describes the ISO sensitivity currently used by the camera.

访问函数：

int isoSensitivity () const

通知程序信号：

void isoSensitivityChanged (int value )

另请参阅 setAutoIsoSensitivity () 和 setManualIsoSensitivity ().

manualIsoSensitivity : int

Describes a manually set ISO sensitivity

Setting this property to -1 (the default), implies that the camera automatically adjusts the ISO sensitivity.

访问函数：

int manualIsoSensitivity () const
void setManualIsoSensitivity (int iso )

通知程序信号：

void manualIsoSensitivityChanged (int)

torchMode : QCamera::TorchMode

This property holds the torch mode being used.

A torch is a continuous source of light. It can be used during video recording in low light conditions. Enabling torch mode will usually override any currently set flash mode.

访问函数：

QCamera::TorchMode torchMode () const
void setTorchMode (QCamera::TorchMode mode )

通知程序信号：

void torchModeChanged ()

另请参阅 QCamera::TorchMode , QCamera::isTorchModeSupported ，和 QCamera::flashMode .

zoomFactor : float

This property holds the current zoom factor.

Gets or sets the current zoom factor. Values will be clamped between minimumZoomFactor and maximumZoomFactor .

访问函数：

float zoomFactor () const
void setZoomFactor (float factor )

通知程序信号：

void zoomFactorChanged (float)

成员函数文档编制

QCamera:: QCamera ( QCameraDevice::Position position , QObject * parent = nullptr)

Construct a QCamera which uses a hardware camera located a the specified position .

For example on a mobile phone it can be used to easily choose between front-facing and back-facing cameras.

If no camera is available at the specified position or if position is QCameraDevice::UnspecifiedPosition , the default camera is used.

QCamera:: QCamera (const QCameraDevice & cameraDevice , QObject * parent = nullptr)

Construct a QCamera from a camera description cameraDevice and parent .

QCamera:: QCamera ( QObject * parent = nullptr)

Construct a QCamera with a parent .

Selects the default camera on the system if more than one camera is available.

[signal] void QCamera:: errorOccurred ( QCamera::Error error , const QString & errorString )

This signal is emitted when error state changes to error . A description of the error is provided as errorString .

[signal] void QCamera:: exposureCompensationChanged ( float value )

Signal emitted when the exposure compensation changes to value .

注意： 通知程序信号对于特性 exposureCompensation .

[signal] void QCamera:: exposureTimeChanged ( float speed )

Signals that a camera's exposure speed 已改变。

注意： 通知程序信号对于特性 exposureTime .

[signal] void QCamera:: flashReady ( bool ready )

Signal the flash ready status has changed.

注意： Notifier signal for property flashReady.

[signal] void QCamera:: isoSensitivityChanged ( int value )

Signal emitted when sensitivity changes to value .

注意： 通知程序信号对于特性 isoSensitivity .

[slot] void QCamera:: setActive ( bool active )

Turns the camera on if active is true , or off if it's false .

注意： setter 函数对于特性 active .

另请参阅 isActive ().

[slot] void QCamera:: setAutoExposureTime ()

Use automatically calculated exposure time

[slot] void QCamera:: setAutoIsoSensitivity ()

Turn on auto sensitivity

[slot] void QCamera:: setColorTemperature ( int colorTemperature )

Sets manual white balance to colorTemperature . This is used when whiteBalanceMode () 被设为 WhiteBalanceManual . The units are Kelvin.

Setting a color temperature will only have an effect if WhiteBalanceManual is supported. In this case, setting a temperature greater 0 will automatically set the white balance mode to WhiteBalanceManual . Setting the temperature to 0 will reset the white balance mode to WhiteBalanceAuto .

注意： setter 函数对于特性 colorTemperature .

另请参阅 colorTemperature ().

[slot] void QCamera:: setManualExposureTime ( float seconds )

Set the manual exposure time to seconds

注意： setter 函数对于特性 manualExposureTime .

另请参阅 manualExposureTime ().

[slot] void QCamera:: setWhiteBalanceMode ( QCamera::WhiteBalanceMode mode )

Sets the white balance to mode .

注意： setter 函数对于特性 whiteBalanceMode .

另请参阅 whiteBalanceMode ().

[slot] void QCamera:: start ()

Starts the camera.

如同 setActive (true)。

If the camera can't be started for some reason, the errorOccurred () 信号被发射。

[slot] void QCamera:: stop ()

Stops the camera. Same as setActive (false).

[slot] void QCamera:: zoomTo ( float factor , float rate )

Zooms to a zoom factor factor 使用 rate .

rate is specified in powers of two per second. At a rate of 1 it would take 2 seconds to go from a zoom factor of 1 to 4.

注意： Using a specific rate is not supported on all cameras. If not supported, zooming will happen as fast as possible.

[虚拟] QCamera:: ~QCamera ()

销毁摄像头对象。

QCameraDevice QCamera:: cameraDevice () const

返回 QCameraDevice object associated with this camera.

注意： Getter function for property cameraDevice.

另请参阅 setCameraDevice ().

QCameraFormat QCamera:: cameraFormat () const

Returns the camera format currently used by the camera.

注意： Getter function for property cameraFormat.

另请参阅 setCameraFormat () 和 QCameraDevice::videoFormats .

QMediaCaptureSession *QCamera:: captureSession () const

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

使用 QMediaCaptureSession::setCamera () to connect the camera to a session.

int QCamera:: colorTemperature () const

Returns the current color temperature if the current white balance mode is WhiteBalanceManual . For other modes the return value is undefined.

注意： Getter function for property colorTemperature.

另请参阅 setColorTemperature ().

QCamera::Error QCamera:: error () const

Returns the error state of the camera.

注意： getter 函数对于特性 error。

QString QCamera:: errorString () const

Returns a human readable string describing a camera's error state.

注意： Getter function for property errorString.

float QCamera:: exposureTime () const

Returns the current exposure time in seconds.

注意： Getter function for property exposureTime.

QPointF QCamera:: focusPoint () const

Returns the point currently used by the auto focus system to focus onto.

注意： Getter function for property focusPoint.

bool QCamera:: isActive () const

Returns true if the camera is currently active.

注意： getter 函数对于特性 active .

bool QCamera:: isAvailable () const

Returns true if the camera can be used.

[invokable] bool QCamera:: isExposureModeSupported ( QCamera::ExposureMode mode ) const

Returns true if the exposure mode is supported.

注意： 此函数可以被援引，通过元对象系统和从 QML。见 Q_INVOKABLE .

[invokable] bool QCamera:: isFlashModeSupported ( QCamera::FlashMode mode ) const

Returns true if the flash mode is supported.

注意： 此函数可以被援引，通过元对象系统和从 QML。见 Q_INVOKABLE .

[invokable] bool QCamera:: isFlashReady () const

Returns true if flash is charged.

注意： 此函数可以被援引，通过元对象系统和从 QML。见 Q_INVOKABLE .

注意： getter 函数对于特性 flashReady .

[invokable] bool QCamera:: isFocusModeSupported ( QCamera::FocusMode mode ) const

Returns true if the focus mode is supported by the camera.

注意： 此函数可以被援引，通过元对象系统和从 QML。见 Q_INVOKABLE .

[invokable] bool QCamera:: isTorchModeSupported ( QCamera::TorchMode mode ) const

Returns true if the torch mode is supported.

注意： 此函数可以被援引，通过元对象系统和从 QML。见 Q_INVOKABLE .

[invokable] bool QCamera:: isWhiteBalanceModeSupported ( QCamera::WhiteBalanceMode mode ) const

Returns true if the white balance mode is supported.

注意： 此函数可以被援引，通过元对象系统和从 QML。见 Q_INVOKABLE .

float QCamera:: manualExposureTime () const

Returns the manual exposure time in seconds, or -1 if the camera is using automatic exposure times.

注意： Getter function for property manualExposureTime.

另请参阅 setManualExposureTime ().

float QCamera:: maximumExposureTime () const

The maximal exposure time in seconds.

int QCamera:: maximumIsoSensitivity () const

Returns the maximum ISO sensitivity supported by the camera.

float QCamera:: maximumZoomFactor () const

Returns the maximum zoom factor.

This will be 1.0 on cameras that do not support zooming.

注意： Getter function for property maximumZoomFactor.

float QCamera:: minimumExposureTime () const

The minimal exposure time in seconds.

int QCamera:: minimumIsoSensitivity () const

Returns the minimum ISO sensitivity supported by the camera.

float QCamera:: minimumZoomFactor () const

Returns the minimum zoom factor.

This will be 1.0 on cameras that do not support zooming.

注意： Getter function for property minimumZoomFactor.

void QCamera:: setCameraDevice (const QCameraDevice & cameraDevice )

Connects the camera object to the physical camera device described by cameraDevice . Using a default constructed QCameraDevice object as cameraDevice will connect the camera to the system default camera device.

注意： setter 函数对于特性 cameraDevice .

另请参阅 cameraDevice ().

void QCamera:: setCameraFormat (const QCameraFormat & format )

Tells the camera to use the format desribed by format . This can be used to define as specific resolution and frame rate to be used for recording and image capture.

注意： setter 函数对于特性 cameraFormat .

另请参阅 cameraFormat ().

void QCamera:: setZoomFactor ( float factor )

Zooms to a zoom factor factor at a rate of 1 factor per second.

注意： setter 函数对于特性 zoomFactor .

另请参阅 zoomFactor ().

QCamera::Features QCamera:: supportedFeatures () const

Returns the features supported by this camera.

注意： Getter function for property supportedFeatures.

另请参阅 QCamera::Feature .

QCamera::WhiteBalanceMode QCamera:: whiteBalanceMode () const

Returns the white balance mode being used.

注意： Getter function for property whiteBalanceMode.

另请参阅 setWhiteBalanceMode ().