Continuous focus on zone for image capture

[Quentin Hébert]

Hello,

Is there a way to have a continuous focus on a zone during an image capture sessions ?

In our app, we are able to determine the wanted focus zone through image analysis, and then to request a one time focus on this zone through [startFocusAndMetering()](https://developer.android.com/reference/androidx/camera/core/CameraControl#startFocusAndMetering(androidx.camera.core.FocusMeteringAction)).

We would like to have a continuous focus on this zone, and even ideally to be able to update this zone.

We tried to call `startFocusAndMetering()` each time the focus action finishes but we end up having either a laggy preview, or a constant "focus breathing" effect.

We are therefore wondering if it would be more efficient to use the camera continuous focus mode on a custom zone, since on the native camera app of a device, it is possible to tap on an object and then the object is tracked and stays in focus even when we move the camera, without the issue we encounter with `startFocusAndMetering()`.

Thanks in advance