The QCameraFocus class provides an interface for focus and zoom related camera settings. 更多...
| 头： | #include <QCameraFocus> |
| qmake: | QT += multimedia |
| 继承： | QObject |
| enum | FocusMode { ManualFocus, HyperfocalFocus, InfinityFocus, AutoFocus, ContinuousFocus, MacroFocus } |
| flags | FocusModes |
| enum | FocusPointMode { FocusPointAuto, FocusPointCenter, FocusPointFaceDetection, FocusPointCustom } |
|
|
| QPointF | customFocusPoint () const |
| qreal | digitalZoom () const |
| FocusModes | focusMode () const |
| FocusPointMode | focusPointMode () const |
| QCameraFocusZoneList | focusZones () const |
| bool | isAvailable () const |
| bool | isFocusModeSupported (FocusModes mode ) const |
| bool | isFocusPointModeSupported (FocusPointMode mode ) const |
| qreal | maximumDigitalZoom () const |
| qreal | maximumOpticalZoom () const |
| qreal | opticalZoom () const |
| void | setCustomFocusPoint (const QPointF & point ) |
| void | setFocusMode (FocusModes mode ) |
| void | setFocusPointMode (FocusPointMode mode ) |
| void | zoomTo (qreal optical , qreal digital ) |
| void | digitalZoomChanged (qreal value ) |
| void | focusZonesChanged () |
| void | maximumDigitalZoomChanged (qreal zoom ) |
| void | maximumOpticalZoomChanged (qreal zoom ) |
| void | opticalZoomChanged (qreal value ) |
The QCameraFocus class provides an interface for focus and zoom related camera settings.
On hardware that supports it, this class lets you adjust the focus or zoom (both optical and digital). This also includes things like "Macro" mode for close up work (e.g. reading barcodes, or recognising letters), or "touch to focus" - indicating an interesting area of the viewfinder for the hardware to attempt to focus on.
QCameraFocus *focus = camera->focus(); focus->setFocusPointMode(QCameraFocus::FocusPointCustom); focus->setCustomFocusPoint(QPointF(0.25f, 0.75f)); // A point near the bottom left, 25% away from the corner, near that shiny vase
Zooming can be accomplished in a number of ways - usually the more expensive but higher quality approach is an optical zoom, which allows using the full extent of the camera sensor to gather image pixels. In addition it is possible to digitally zoom, which will generally just enlarge part of the sensor frame and throw away other parts. If the camera hardware supports optical zoom this should generally always be used first. The maximumOpticalZoom () method allows this to be checked. The zoomTo () method allows changing both optical and digital zoom at once.
focus->zoomTo(3.0, 4.0); // Super zoom!
Some hardware supports a movable focus lens assembly, and typically this hardware also supports automatically focusing via some heuristic. You can influence this via the FocusPointMode setting - typically the center of the frame is brought into focus, but some hardware also supports focusing on any faces detected in the frame, or on a specific point (usually provided by a user in a "touch to focus" scenario).
This class (in combination with QCameraFocusZone ) can expose information on what parts of the camera sensor image are in focus or are being used for autofocusing via the focusZones () 特性：
focus->setFocusPointMode(QCameraFocus::FocusPointAuto); QList<QCameraFocusZone> zones = focus->focusZones(); foreach (QCameraFocusZone zone, zones) { if (zone.status() == QCameraFocusZone::Focused) { // Draw a green box at zone.area() } else if (zone.status() == QCameraFocusZone::Selected) { // This area is selected for autofocusing, but is not in focus // Draw a yellow box at zone.area() } }
另请参阅 QCameraFocusZone .
| 常量 | 值 | 描述 |
|---|---|---|
QCameraFocus::ManualFocus
|
0x1
|
Manual or fixed focus mode. |
QCameraFocus::HyperfocalFocus
|
0x02
|
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. |
QCameraFocus::InfinityFocus
|
0x04
|
Focus strictly to infinity. |
QCameraFocus::AutoFocus
|
0x8
|
One-shot auto focus mode. |
QCameraFocus::ContinuousFocus
|
0x10
|
Continuous auto focus mode. |
QCameraFocus::MacroFocus
|
0x20
|
One shot auto focus to objects close to camera. |
FocusModes 类型是 typedef 对于 QFlags <FocusMode>. It stores an OR combination of FocusMode values.
| 常量 | 值 | 描述 |
|---|---|---|
QCameraFocus::FocusPointAuto
|
0
|
Automatically select one or multiple focus points. |
QCameraFocus::FocusPointCenter
|
1
|
Focus to the frame center. |
QCameraFocus::FocusPointFaceDetection
|
2
|
Focus on faces in the frame. |
QCameraFocus::FocusPointCustom
|
3
|
Focus to the custom point, defined by QCameraFocus::customFocusPoint 特性。 |
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.
访问函数：
| QPointF | customFocusPoint () const |
| void | setCustomFocusPoint (const QPointF & point ) |
This property holds the current digital zoom value.
访问函数：
| qreal | digitalZoom () const |
通知程序信号：
| void | digitalZoomChanged (qreal value ) |
另请参阅 QCameraFocus::opticalZoom .
This property holds the current camera focus mode.
This controls the way the camera lens assembly is configured.
访问函数：
| FocusModes | focusMode () const |
| void | setFocusMode (FocusModes mode ) |
另请参阅 QCameraFocus::isFocusModeSupported ().
This property holds the current camera focus point selection mode.
If the camera focus mode is set to use an autofocusing mode, this property controls the way the camera will select areas of the frame to use for autofocusing.
访问函数：
| FocusPointMode | focusPointMode () const |
| void | setFocusPointMode (FocusPointMode mode ) |
另请参阅 QCameraFocus::isFocusPointModeSupported ().
Returns the list of active focus zones.
If QCamera::FocusPointAuto or QCamera::FocusPointFaceDetection focus mode is selected this method returns the list of zones the camera is actually focused on.
The coordinates system is the same as for custom focus points: QPointF (0,0) points to the left top frame point, QPointF (0.5,0.5) points to the frame center.
访问函数：
| QCameraFocusZoneList | focusZones () const |
通知程序信号：
| void | focusZonesChanged () |
This property holds the current optical zoom value.
访问函数：
| qreal | opticalZoom () const |
通知程序信号：
| void | opticalZoomChanged (qreal value ) |
另请参阅 QCameraFocus::digitalZoom .
[signal]
void
QCameraFocus::
digitalZoomChanged
(
qreal
value
)
Signal emitted when digital zoom value changes to new value .
注意： 通知程序信号对于特性 digitalZoom .
[signal]
void
QCameraFocus::
focusZonesChanged
()
This signal is emitted when the set of zones used in autofocusing is changed.
This can change when a zone is focused or loses focus, or new focus zones have been detected.
注意： 通知程序信号对于特性 focusZones .
Returns true if focus related settings are supported by this camera.
You may need to also check if any specific features are supported.
Returns true if the focus mode is supported by camera.
Returns true if focus point mode is supported.
Returns the maximum digital zoom
This will be
1.0
on cameras that do not support digital zoom.
[signal]
void
QCameraFocus::
maximumDigitalZoomChanged
(
qreal
zoom
)
Signal emitted when the maximum supported digital zoom value changed.
The maximum supported zoom value can depend on other camera settings, like capture mode or resolution.
Returns the maximum optical zoom.
This will be
1.0
on cameras that do not support optical zoom.
[signal]
void
QCameraFocus::
maximumOpticalZoomChanged
(
qreal
zoom
)
Signal emitted when the maximum supported optical zoom value changed.
[signal]
void
QCameraFocus::
opticalZoomChanged
(
qreal
value
)
Signal emitted when optical zoom value changes to new value .
注意： 通知程序信号对于特性 opticalZoom .
Set the camera optical and digital 缩放值。
Since there may be a physical component to move, the change in zoom value may not be instantaneous.