CameraX does not support zoom out below 1

[Anshul Sharma]

Hi, I am trying to implement cameraX zoom out feature, My device supports zoom out till 0.6x in device camera, but cameraX allows me to set zoomRatio(1) only, nothing happens if I set it below 1. Also, cameraInfo.zoomState.value!!.minZoomRatio always returns 1 in every device.

camera_x_version = '1.1.0-alpha04'

NOTE: Zoom in working fine till cameraInfo.zoomState.value!!.maxZoomRatio

Code to perform zoom

private fun setupZoomAndTapToFocus() {
val listener = object : ScaleGestureDetector.SimpleOnScaleGestureListener() {
override fun onScale(detector: ScaleGestureDetector): Boolean {
currentZoomRatio = cameraInfo.zoomState.value?.zoomRatio ?: 1F
delta = detector.scaleFactor
Log.d(TAG, "delta - curRatio:$delta,$currentZoomRatio")
cameraControl.setZoomRatio(currentZoomRatio * delta)

return true
}
}

val scaleGestureDetector = ScaleGestureDetector(viewFinder?.context, listener)

viewFinder?.setOnTouchListener { _, event ->
scaleGestureDetector.onTouchEvent(event)
if (event.action == MotionEvent.ACTION_DOWN) {
val factory = viewFinder?.meteringPointFactory
val point = factory?.createPoint(event.x, event.y)
val action = FocusMeteringAction.Builder(point!!, FocusMeteringAction.FLAG_AF)
.setAutoCancelDuration(5, TimeUnit.SECONDS)
.build()
cameraControl.startFocusAndMetering(action)
}
true
}
}

[Scott Nien]

Hi Anshul, 

To support <1 zoom requires OEM to implement the smooth zoom via CONTROL_ZOOM_RATIO.  Currently, not every device supports that. 

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[Anshul Sharma]

@Scott Thanks for the quick response.

Can you please explain this 'OEM process' a little more or any document/link explaining this 'OEM process' to have a better understanding.

[Scott Nien]

Sure, see the link here for more information. 

• (Android 11 or higher) For a logical multi-camera device supporting optical zoom, implement the ANDROID_CONTROL_ZOOM_RATIO API, and use ANDROID_SCALER_CROP_REGION for aspect ratio cropping only. ANDROID_CONTROL_ZOOM_RATIO enables the device to zoom out and maintain better precision. In this case, the HAL must adjust the coordinates system of ANDROID_SCALER_CROP_REGION, ANDROID_CONTROL_AE_REGIONS, ANDROID_CONTROL_AWB_REGIONS, ANDROID_CONTROL_AF_REGIONS, ANDROID_STATISTICS_FACE_RECTANGLES, and ANDROID_STATISTICS_FACE_LANDMARKS to treat the post-zoom field of view as the sensor active array. For more information on how ANDROID_SCALER_CROP_REGION works together with ANDROID_CONTROL_ZOOM_RATIO, see camera3_crop_reprocess#cropping.

[Anshul Sharma]

Thanks for this useful link. But I want to implement the zoom out feature in all the devices(Below Android 11 also) in which there is zoom out support in device camera. My device Poco x2 supports zoom out till 0.6x but my Camerax does not allow me to zoom out below 1x. Is there any possible solution for that?

[Scott Nien]

That's not feasible currently. You might be able to open the camera id of the wide angle camera,  but it would be very difficult to make it smoothly transition from wide angle camera to normal camera. 
So the best you can do is to have an option to switch the lens (normal or wide angle) and zoom works separately on each lens.