How to use manual focus in Android CameraX?

Question

I am trying to do manual focus on CameraX the same as I do in Camera2 API

in Camera2 API I use the following code

final CaptureRequest.Builder captureBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE); 

captureBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_OFF); 

captureBuilder.set(CaptureRequest.LENS_FOCUS_DISTANCE, mLensFocusDistance);

Can manual focus be done in android camera X? If so how

Thanks in advance

no camera X is currently unable to https://groups.google.com/a/android.com/forum/#!searchin/camerax-developers/focus%7Csort:date/camerax-developers/ySfolLe_AS8/hOhHRViaCgAJ — moLand, Mar 06 '20 at 10:23

score 11 · Accepted Answer · edited Mar 12 '21 at 14:41

There is a way to use manual focus in cameraX by accessing low-level camera2 API with Camera2Interop.Extender. You should set two extra options to preview builder like this:

void setFocusDistance(ExtendableBuilder<?> builder, float distance) {
    Camera2Interop.Extender extender = new Camera2Interop.Extender(builder);
    extender.setCaptureRequestOption(CaptureRequest.CONTROL_AF_MODE, CameraMetadata.CONTROL_AF_MODE_OFF);
    extender.setCaptureRequestOption(CaptureRequest.LENS_FOCUS_DISTANCE, distance);
}

And use it when building your cameraX preview request:

float focusDistance = 0F; // example: infinite focus
Preview.Builder previewBuilder = new Preview.Builder();
setFocusDistance(previewBuilder, focusDistance);
preview = previewBuilder.build();
preview.setSurfaceProvider(viewFinder.getSurfaceProvider());

Note that you may also set other camera2 CaptureRequest options in this manner.

Here's how to find the LENS_INFO_MINIMUM_FOCUS_DISTANCE (often a value around 10f):

theCamera = cameraProvider.bindToLifecycle(...
CameraCharacteristics camChars = Camera2CameraInfo
   .extractCameraCharacteristics(theCamera.getCameraInfo());
float discoveredMinFocusDistance = camChars
   .get(CameraCharacteristics.LENS_INFO_MINIMUM_FOCUS_DISTANCE);
Log.i("dev", "found it! " + discoveredMinFocusDistance);

unfortunately this only works when launching the camera, not while it is running :/ — Fattie, Mar 12 '21 at 15:04
@Fattie true, you should restart camera to update the focusing mode now :( — Mikhail, Mar 12 '21 at 21:18

Misha Akopov · Answer 2 · 2019-12-02T12:23:41.833

0

You should set TouchListener to textureView and then set focus(Kotlin):

private fun setUpTapToFocus() {
    textureView.setOnTouchListener { _, event ->
        if (event.action != MotionEvent.ACTION_UP) {
            return false
        }

        val cameraControl = CameraX.getCameraControl(CameraX.LensFacing.BACK) // you can set it to front                     
        val factory = TextureViewMeteringPointFactory(textureView)
        val point = factory.createPoint(event.x, event.y)
        val action = FocusMeteringAction.Builder.from(point).build()
        cameraControl.startFocusAndMetering(action)
        return true
    }
}

Hope that helps

edited Dec 02 '19 at 12:23

answered Dec 02 '19 at 12:17

Misha Akopov

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thank you for your answer @Misha however, this is the same as tap to focus. I am trying to set the focus level – moLand Dec 03 '19 at 10:56
Yes, from what I read,I thought manual focusing meant to focus by tapping :) – Misha Akopov Dec 03 '19 at 14:46

How to use manual focus in Android CameraX?

2 Answers2