FocusMeteringAction

public final class FocusMeteringAction
extends Object

java.lang.Object
   ↳ androidx.camera.core.FocusMeteringAction


A configuration used to trigger a focus and/or metering action.

A FocusMeteringAction must be created by the FocusMeteringAction.Builder. To construct a FocusMeteringAction.Builder, a MeteringPoint is required to specify the focus/metering area. Apps can use various MeteringPointFactory to create the points. After the FocusMeteringAction is built, apps can pass it to CameraControl.startFocusAndMetering(FocusMeteringAction) to initiate the focus and metering action.

When specifying a MeteringPoint, a metering mode can also be specified. Metering mode is a combination of flags consisting of FLAG_AF, FLAG_AE, and FLAG_AWB. This combination indicates whether the MeteringPoint is used to set an AF(Auto Focus) region, AE(Auto Exposure) region or AWB(Auto White Balance) region. The default meteringMode is FLAG_AF | FLAG_AE | FLAG_AWB which means the point is used for all AF/AE/AWB regions. Apps can set the proper metering mode to optionally exclude some 3A regions. Multiple regions for specific 3A types are also supported via FocusMeteringAction.Builder.addPoint(MeteringPoint) or FocusMeteringAction.Builder.addPoint(MeteringPoint, int). An app can also use this API to enable different regions for AF and AE respectively.

If any AF points are specified, it will trigger autofocus to start a manual scan. When focus is locked and the specified AF/AE/AWB regions are updated in capture result, the returned ListenableFuture in CameraControl.startFocusAndMetering(FocusMeteringAction) will complete with FocusMeteringResult.isFocusSuccessful() set to indicate if focus is done successfully or not. If an AF point is not specified, it will not trigger autofocus and simply wait for specified AE/AWB regions being updated to complete the returned ListenableFuture. In the case of AF points not specified, FocusMeteringResult.isFocusSuccessful() will be set to false. If Af points are specified but current camera does not support auto focus, FocusMeteringResult.isFocusSuccessful() will be set to true .

App can set a auto-cancel duration to let CameraX call CameraControl.cancelFocusAndMetering() automatically in the specified duration. By default the auto-cancel duration is 5 seconds. Apps can call FocusMeteringAction.Builder.disableAutoCancel() to disable auto-cancel.

Summary

Nested classes

class FocusMeteringAction.Builder

The builder used to create the FocusMeteringAction

Constants

int FLAG_AE