QCameraFocus

PyQt5.QtMultimedia.QCameraFocus

Inherits from QObject.

Description

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 notes on autofocus

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() property:

#     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()
#         }
#     }

See also

QCameraFocusZone.

Classes

FocusModes

Enums

FocusMode

Member	Value	Description
AutoFocus	0x8	One-shot auto focus mode.
ContinuousFocus	0x10	Continuous auto focus mode.
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.
InfinityFocus	0x04	Focus strictly to infinity.
MacroFocus	0x20	One shot auto focus to objects close to camera.
ManualFocus	0x1	Manual or fixed focus mode.

---

FocusPointMode

Member	Value	Description
FocusPointAuto	0	Automatically select one or multiple focus points.
FocusPointCenter	1	Focus to the frame center.
FocusPointCustom	3	Focus to the custom point, defined by customFocusPoint() property.
FocusPointFaceDetection	2	Focus on faces in the frame.

Methods

customFocusPoint() → QPointF

See also

setCustomFocusPoint().

---

digitalZoom() → float

TODO

---

focusMode() → FocusModes

See also

setFocusMode().

---

focusPointMode() → FocusPointMode

See also

setFocusPointMode().

---

focusZones() → List[QCameraFocusZone]

TODO

---

isAvailable() → bool

Returns true if focus related settings are supported by this camera.

You may need to also check if any specific features are supported.

---

isFocusModeSupported(Union[FocusModes, FocusMode]) → bool

TODO

---

isFocusPointModeSupported(FocusPointMode) → bool

Returns true if focus point mode is supported.

---

maximumDigitalZoom() → float

Returns the maximum digital zoom

This will be 1.0 on cameras that do not support digital zoom.

---

maximumOpticalZoom() → float

Returns the maximum optical zoom.

This will be 1.0 on cameras that do not support optical zoom.

---

opticalZoom() → float

TODO

---

setCustomFocusPoint(Union[QPointF, QPoint])

See also

customFocusPoint().

---

setFocusMode(Union[FocusModes, FocusMode])

TODO

---

setFocusPointMode(FocusPointMode)

See also

focusPointMode().

---

zoomTo(float, float)

Set the camera optical and digital zoom values.

Since there may be a physical component to move, the change in zoom value may not be instantaneous.

Signals

digitalZoomChanged(float)

TODO

---

focusZonesChanged()

TODO

---

maximumDigitalZoomChanged(float)

TODO

---

maximumOpticalZoomChanged(float)

TODO

---

opticalZoomChanged(float)

TODO