与焦点和缩放相关的摄像头设置接口。 更多...
| import 语句： |
import QtMultimedia
|
| 在 C++： | QCamera |
The Camera element can be used within a CaptureSession 为视频录制和图像获取。
可以使用 MediaDevices 列表可用摄像头并选取要使用的摄像头。
MediaDevices {
id: mediaDevices
}
CaptureSession {
camera: Camera {
cameraDevice: mediaDevices.defaultVideoInput
}
}
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.
Item { width: 640 height: 360 CaptureSession { camera: Camera { id: camera focusMode: Camera.FocusModeAutoNear customFocusPoint: Qt.point(0.2, 0.2) // Focus relative to top-left corner } videoOutput: videoOutput } VideoOutput { id: videoOutput anchors.fill: parent } }
The minimumZoomFactor and maximumZoomFactor properties provide the range of supported zoom factors. The zoomFactor property allows changing the zoom factor.
Camera { zoomFactor: maximumZoomFactor // zoom in as much as possible }
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 { whiteBalanceMode: Camera.WhiteBalanceManual colorTemperature: 5600 }
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。
|
active : bool |
Describes whether the camera is currently active.
|
cameraDevice : cameraDevice |
Gets or sets the currently active camera device.
When switching camera devices, the QCamera 's capabilities are updated. Additionally, the QCamera 's control properties (such as focusMode , flashMode , focusDistance , zoomFactor ) are updated as follows:
|
cameraFormat : cameraFormat |
Gets or sets the currently active camera format.
注意： When using the FFMPEG backend on an Android target device if you request YUV420P format, you will receive either a fully planar 4:2:0 YUV420P or a semi-planar NV12/NV21. This depends on the codec implemented by the device OEM.
另请参阅 cameraDevice::videoFormats .
|
customFocusPoint : point |
This property holds the position of custom focus point, in relative frame coordinates. This means that QPointF (0,0) points to the top-left corner of the frame, and QPointF (0.5,0.5) points to the center of the frame.
Custom focus point is used only in
FocusPointCustom
focus mode.
You can check whether custom focus points are supported by querying supportedFeatures() with the Feature.CustomFocusPoint flag.
|
error
:
enumeration
|
Returns the error state of the camera.
另请参阅 QCamera::Error .
|
errorString
:
string
|
Returns a human readable string describing a camera's error state.
|
exposureCompensation : real |
Gets or sets the exposure compensation in EV units.
Exposure compensation property allows to adjust the automatically calculated exposure.
|
exposureMode : ExposureMode |
The exposure mode being used.
另请参阅 QCamera::ExposureMode and Camera::isExposureModeSupported ().
|
exposureTime
:
real
|
Returns the Camera's exposure time in seconds.
另请参阅 manualExposureTime .
|
flashMode : enumeration |
Gets or sets a certain flash mode if the camera has a flash.
Assigning an unsupported mode to this property has no effect.
This property only has an effect when capturing images using ImageCapture
| 常量 | 描述 |
|---|---|
Camera.FlashOff
|
Flash is Off. |
Camera.FlashOn
|
Flash is On. |
Camera.FlashAuto
|
自动闪光。 |
另请参阅 isFlashModeSupported and isFlashReady .
|
flashReady
:
bool
|
Indicates if the flash is charged and ready to use.
|
focusDistance : real |
This property defines the lens focus distance when the camera device works in manual focus mode. Valid values range from 0 to 1, where 0 is the closest possible focus distance, and 1 is the farthest. The farthest point is typically at infinity, but this may not be the case for all devices.
This property is applied to the device only when
focusMode
被设为
Camera.FocusModeManual
，和
supportedFeatures
includes the
Camera.FocusDistance
标志。
If you assign a value to this property while
focusMode
is not set to
Camera.FocusModeManual
, the property stores the value but does not affect the device until
Camera.FocusModeManual
is active.
Assigning a value outside the valid range [0, 1] has no effect on this property.
若
supportedFeatures
does not include the
Camera.FocusDistance
flag, any attempt to set this property is ignored.
This property will not be updated by the camera when it is in an automatic focus mode.
默认值为 1。
|
focusMode : enumeration |
This property holds the value that controls focus mode for the camera device. In all autofocus modes, the camera device keeps focusing continuously.
注意： In automatic focusing modes and where supported, the focusPoint property provides information and control over the area of the image that is being focused.
| 常量 | 描述 |
|---|---|
Camera.FocusModeAuto
|
Continuous auto focus mode. |
Camera.FocusModeAutoNear
|
Continuous auto focus, preferring objects near to the camera. |
Camera.FocusModeAutoFar
|
Continuous auto focus, preferring objects far away from the camera. |
Camera.FocusModeHyperfocal
|
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. |
Camera.FocusModeInfinity
|
Focus strictly to infinity. |
Camera.FocusModeManual
|
The lens focus distance is set to a value specified by focusDistance . |
To check whether the camera device supports a particular focus mode, pass the corresponding
focusMode
value to the
isFocusModeSupported
() function as a parameter. The function returns
false
if the focus mode value is not supported. Assigning an unsupported mode to this property has no effect.
If you set the focusMode property to
Camera.FocusModeManual
, the lens locks to the focus according to
focusDistance
.
另请参阅 isFocusModeSupported ().
|
focusPoint
:
point
|
Returns the point currently used by the auto focus system to focus onto.
|
isoSensitivity
:
int
|
Describes the ISO sensitivity currently used by the camera.
|
manualExposureTime : real |
Gets or sets a manual exposure time.
Setting this property to -1 (the default) means that the camera automatically determines the exposure time.
|
manualIsoSensitivity : int |
Describes a manually set ISO sensitivity
Setting this property to -1 (the default), implies that the camera automatically adjusts the ISO sensitivity.
|
maximumZoomFactor
:
real
|
This property holds the maximum zoom factor supported.
This will be
1.0
on cameras that do not support zooming.
|
minimumZoomFactor
:
real
|
This property holds the minimum zoom factor supported.
This will be
1.0
on cameras that do not support zooming.
|
supportedFeatures
:
特征
|
Returns the features supported by this camera.
另请参阅 QCamera::Feature .
|
torchMode : Camera::TorchMode |
Gets or sets 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.
另请参阅 QCamera::TorchMode , Camera::isTorchModeSupported ()，和 Camera::flashMode .
|
whiteBalanceMode : WhiteBalanceMode |
Gets or sets the white balance mode being used.
另请参阅 QCamera::WhiteBalanceMode .
|
zoomFactor : real |
Gets or sets the current zoom factor. Values will be clamped between minimumZoomFactor and maximumZoomFactor .
|
void errorOccurred ( Camera::Error error , string errorString ) |
This signal is emitted when error state changes to error . A description of the error is provided as errorString .
注意：
相应处理程序是
onErrorOccurred
.
|
colorTemperature () |
Gets or sets the current color temperature.
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.
|
bool isExposureModeSupported ( ExposureMode mode ) |
Returns true if the exposure mode is supported.
|
bool isFlashModeSupported ( FlashMode mode ) |
Returns true if the flash mode is supported.
|
bool isFlashReady () |
Returns true if flash is charged.
|
bool isFocusModeSupported ( FocusMode mode ) |
返回
true
if the focus
mode
is supported by the camera.
若 Camera.FocusModeManual is reported as supported, the feature Camera.FocusDistance is implied to be supported as well.
|
bool isTorchModeSupported ( TorchMode mode ) |
Returns true if the torch mode is supported.
|
bool isWhiteBalanceModeSupported ( WhiteBalanceMode mode ) |
Returns true if the white balance mode is supported.
|
void start () |
Starts the camera.
Same as setting the active property to true.
If the camera can't be started for some reason, the errorOccurred () 信号发射。
|
void stop () |
Stops the camera. Same as setting the active property to false.
|
void zoomTo ( factor , rate ) |
Zooms to a zoom factor factor 使用 rate .
The 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.