QCameraFocus

The QCameraFocus class provides an interface for focus and zoom related camera settings. More

Inheritance diagram of PySide2.QtMultimedia.QCameraFocus

Synopsis

Functions

Signals

Detailed Description

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);
const QList<QCameraFocusZone> zones = focus->focusZones();
for (const 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

PySide2.QtMultimedia.QCameraFocus.FocusMode

Constant

Description

QCameraFocus.ManualFocus

Manual or fixed focus mode.

QCameraFocus.HyperfocalFocus

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

Focus strictly to infinity.

QCameraFocus.AutoFocus

One-shot auto focus mode.

QCameraFocus.ContinuousFocus

Continuous auto focus mode.

QCameraFocus.MacroFocus

One shot auto focus to objects close to camera.

PySide2.QtMultimedia.QCameraFocus.FocusPointMode

Constant

Description

QCameraFocus.FocusPointAuto

Automatically select one or multiple focus points.

QCameraFocus.FocusPointCenter

Focus to the frame center.

QCameraFocus.FocusPointFaceDetection

Focus on faces in the frame.

QCameraFocus.FocusPointCustom

Focus to the custom point, defined by customFocusPoint property.

PySide2.QtMultimedia.QCameraFocus.customFocusPoint()
Return type

QPointF

PySide2.QtMultimedia.QCameraFocus.digitalZoom()
Return type

qreal

PySide2.QtMultimedia.QCameraFocus.digitalZoomChanged(arg__1)
Parameters

arg__1qreal

PySide2.QtMultimedia.QCameraFocus.focusMode()
Return type

FocusModes

See also

setFocusMode()

PySide2.QtMultimedia.QCameraFocus.focusPointMode()
Return type

FocusPointMode

PySide2.QtMultimedia.QCameraFocus.focusZones()
Return type

PySide2.QtMultimedia.QCameraFocus.focusZonesChanged()
PySide2.QtMultimedia.QCameraFocus.isAvailable()
Return type

bool

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

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

PySide2.QtMultimedia.QCameraFocus.isFocusModeSupported(mode)
Parameters

modeFocusModes

Return type

bool

Returns true if the focus mode is supported by camera.

PySide2.QtMultimedia.QCameraFocus.isFocusPointModeSupported(arg__1)
Parameters

arg__1FocusPointMode

Return type

bool

Returns true if focus point mode is supported.

PySide2.QtMultimedia.QCameraFocus.maximumDigitalZoom()
Return type

qreal

Returns the maximum digital zoom

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

PySide2.QtMultimedia.QCameraFocus.maximumDigitalZoomChanged(arg__1)
Parameters

arg__1qreal

PySide2.QtMultimedia.QCameraFocus.maximumOpticalZoom()
Return type

qreal

Returns the maximum optical zoom.

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

PySide2.QtMultimedia.QCameraFocus.maximumOpticalZoomChanged(arg__1)
Parameters

arg__1qreal

PySide2.QtMultimedia.QCameraFocus.opticalZoom()
Return type

qreal

PySide2.QtMultimedia.QCameraFocus.opticalZoomChanged(arg__1)
Parameters

arg__1qreal

PySide2.QtMultimedia.QCameraFocus.setCustomFocusPoint(point)
Parameters

pointQPointF

PySide2.QtMultimedia.QCameraFocus.setFocusMode(mode)
Parameters

modeFocusModes

See also

focusMode()

PySide2.QtMultimedia.QCameraFocus.setFocusPointMode(mode)
Parameters

modeFocusPointMode

See also

focusPointMode()

PySide2.QtMultimedia.QCameraFocus.zoomTo(opticalZoom, digitalZoom)
Parameters
  • opticalZoomqreal

  • digitalZoomqreal

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.