QtMultimedia.Camera

Access viewfinder frames, and take photos and movies. More...

Properties

• availability : enumeration
• cameraState : enumeration
• cameraStatus : enumeration
• captureMode : enumeration
• deviceId : string
• digitalZoom : real
• displayName : string
• errorCode : enumeration
• errorString : string
• lockStatus : enumeration
• maximumDigitalZoom : real
• maximumOpticalZoom : real
• mediaObject : variant
• metaData
  • metaData.gpsLatitude : variant
  • metaData.gpsLongitude : variant
  • metaData.gpsAltitude : variant
• metaData.cameraManufacturer : variant
• metaData.cameraModel : variant
• metaData.dateTimeOriginal : variant
• metaData.event : variant
• metaData.gpsImgDirection : variant
• metaData.gpsProcessingMethod : variant
• metaData.gpsSpeed : variant
• metaData.gpsTimestamp : variant
• metaData.gpsTrack : variant
• metaData.orientation : variant
• metaData.subject : variant
• opticalZoom : real
• orientation : int
• position : enumeration
• viewfinder
  • viewfinder.minimumFrameRate : real
  • viewfinder.maximumFrameRate : real
• viewfinder.resolution : size

Signals

• cameraStateChanged(state)
• digitalZoomChanged(zoom)
• error(errorCode, errorString)
• lockStatusChanged()
• manualWhiteBalanceChanged(qreal)
• maximumDigitalZoomChanged(zoom)
• maximumOpticalZoomChanged(zoom)
• opticalZoomChanged(zoom)
• whiteBalanceModeChanged(Camera::WhiteBalanceMode)

Methods

• searchAndLock()
• start()
• stop()
• unlock()

Detailed Description

You can use Camera to capture images and movies from a camera, and manipulate the capture and processing settings that get applied to the images. To display the viewfinder you can use VideoOutput with the Camera set as the source.

import QtQuick 2.0
import QtMultimedia 5.4
Item {
width: 640
height: 360
Camera {
id: camera
imageProcessing.whiteBalanceMode: CameraImageProcessing.WhiteBalanceFlash
exposure {
exposureCompensation: -1.0
exposureMode: Camera.ExposurePortrait
}
flash.mode: Camera.FlashRedEyeReduction
imageCapture {
onImageCaptured: {
photoPreview.source = preview  // Show the preview in an Image
}
}
}
VideoOutput {
source: camera
anchors.fill: parent
focus : visible // to receive focus and capture key events when visible
}
Image {
id: photoPreview
}
}

If multiple cameras are available, you can select which one to use by setting the deviceId property to a value from QtMultimedia.availableCameras. On a mobile device, you can conveniently switch between front-facing and back-facing cameras by setting the position property.

The various settings and functionality of the Camera stack is spread across a few different child properties of Camera.

Basic camera state management, error reporting, and simple zoom properties are available in the Camera itself. For integration with C++ code, the mediaObject property allows you to access the standard Qt Multimedia camera controls.

Many of the camera settings may take some time to apply, and might be limited to certain supported values depending on the hardware. Some camera settings may be set manually or automatically. These settings properties contain the current set value. For example, when autofocus is enabled the focus zones are exposed in the focus property.

For additional information, read also the camera overview.

Property Documentation

This property holds the availability state of the camera.

The availability states can be one of the following:

This property holds the camera object's current state, which can be one of the following:

The default camera state is ActiveState.

This property holds the camera object's current status, which can be one of the following:

This property holds the camera capture mode, which can be one of the following:

The default capture mode is CaptureStillImage.

This property holds the unique identifier for the camera device being used. It may not be human-readable.

You can get all available device IDs from QtMultimedia.availableCameras. If no value is provided or if set to an empty string, the system's default camera will be used.

If possible, cameraState, captureMode, digitalZoom and other camera parameters are preserved when changing the camera device.

This QML property was introduced in QtMultimedia 5.4.

See also displayName and position.

This property holds the current digital zoom factor.

This property holds the human-readable name of the camera.

You can use this property to display the name of the camera in a user interface.

This QML property was introduced in QtMultimedia 5.4.

See also deviceId.

This property holds the last error code.

See also error and errorString.

This property holds the last error string, if any.

See also error and errorCode.

This property holds the status of all the requested camera locks.

The status can be one of the following values:

This property holds the maximum digital zoom factor supported, or 1.0 if digital zoom is not supported.

This property holds the maximum optical zoom factor supported, or 1.0 if optical zoom is not supported.

This property holds the media object for the camera.

These properties hold the the geographic position in decimal degrees of the camera at time of capture.

This property group was introduced in Qt 5.4.

See also QMediaMetaData.

This property holds the name of the manufacturer of the camera.

This QML property was introduced in Qt 5.4.

See also QMediaMetaData.

This property holds the name of the model of the camera.

This QML property was introduced in Qt 5.4.

See also QMediaMetaData.

This property holds the initial time at which the photo or video is captured.

This QML property was introduced in Qt 5.4.

See also QMediaMetaData.

This property holds the event during which the photo or video is to be captured.

This QML property was introduced in Qt 5.4.

See also QMediaMetaData.

This property holds direction the camera is facing at the time of capture. It is measured in degrees clockwise from north.

This QML property was introduced in Qt 5.4.

See also QMediaMetaData.

This property holds the name of the method for determining the GPS position data.

This QML property was introduced in Qt 5.4.

See also QMediaMetaData.

This property holds the velocity in kilometers per hour of the camera at time of capture.

This QML property was introduced in Qt 5.4.

See also QMediaMetaData.

This property holds the timestamp of the GPS position data.

This QML property was introduced in Qt 5.4.

See also QMediaMetaData.

This property holds direction of movement of the camera at the time of capture. It is measured in degrees clockwise from north.

This QML property was introduced in Qt 5.4.

See also QMediaMetaData.

This property holds the clockwise rotation of the camera at time of capture.

This QML property was introduced in Qt 5.4.

See also QMediaMetaData.

This property holds the name of the subject of the capture or recording.

This QML property was introduced in Qt 5.4.

See also QMediaMetaData.

This property holds the current optical zoom factor.

This property holds the physical orientation of the camera sensor.

The value is the orientation angle (clockwise, in steps of 90 degrees) of the camera sensor in relation to the display in its natural orientation.

For example, suppose a mobile device which is naturally in portrait orientation. The back-facing camera is mounted in landscape. If the top side of the camera sensor is aligned with the right edge of the screen in natural orientation, orientation returns 270. If the top side of a front-facing camera sensor is aligned with the right edge of the screen, orientation returns 90.

This QML property was introduced in QtMultimedia 5.4.

See also VideoOutput::orientation.

This property holds the physical position of the camera on the hardware system.

The position can be one of the following:

• Camera.UnspecifiedPosition - the camera position is unspecified or unknown.
• Camera.BackFace - the camera is on the back face of the system hardware. For example on a mobile device, it means it is on the opposite side to that of the screem.
• Camera.FrontFace - the camera is on the front face of the system hardware. For example on a mobile device, it means it is on the same side as that of the screen. Viewfinder frames of front-facing cameras are mirrored horizontally, so the users can see themselves as looking into a mirror. Captured images or videos are not mirrored.

On a mobile device it can be used to easily choose between front-facing and back-facing cameras. If this property is set to Camera.UnspecifiedPosition, the system's default camera will be used.

If possible, cameraState, captureMode, digitalZoom and other camera parameters are preserved when changing the camera device.

This QML property was introduced in QtMultimedia 5.4.

See also deviceId.

These properties hold the limits of the preferred frame rate for the viewfinder in frames per second.

This property group was introduced in Qt 5.4.

This property holds the resolution of the camera viewfinder. If no resolution is given the backend will use a default value.

This QML property was introduced in Qt 5.4.

Signal Documentation

This signal is emitted when the camera state has changed to state. Since the state changes may take some time to occur this signal may arrive sometime after the state change has been requested.

The corresponding handler is onCameraStateChanged.

This signal is emitted when the digital zoom setting has changed to zoom.

The corresponding handler is onDigitalZoomChanged.

This signal is emitted when an error occurs. The enumeration value errorCode is one of the values defined below, and a descriptive string value is available in errorString.

The corresponding handler is onError.

See also errorCode and errorString.

This signal is emitted when the lock status (focus, exposure etc) changes. This can happen when locking (e.g. autofocusing) is complete or has failed.

The corresponding handler is onLockStatusChanged.

This signal is emitted when the manualWhiteBalance property is changed.

The corresponding handler is onManualWhiteBalanceChanged.

This signal is emitted when the maximum digital zoom setting has changed to zoom. This can occur when you change between video and still image capture modes, or the capture settings are changed.

The corresponding handler is onMaximumDigitalZoomChanged.

This signal is emitted when the maximum optical zoom setting has changed to zoom. This can occur when you change between video and still image capture modes, or the capture settings are changed.

The corresponding handler is onMaximumOpticalZoomChanged.

This signal is emitted when the optical zoom setting has changed to zoom.

The corresponding handler is onOpticalZoomChanged.

This signal is emitted when the whiteBalanceMode property is changed.

The corresponding handler is onWhiteBalanceModeChanged.

Method Documentation

Start focusing, exposure and white balance calculation.

This is appropriate to call when the camera focus button is pressed (or on a camera capture button half-press). If the camera supports autofocusing, information on the focus zones is available through the focus property.

Starts the camera. Viewfinder frames will be available and image or movie capture will be possible.

Stops the camera, but leaves the camera stack loaded.

Unlock focus, exposure and white balance locks.