IssueTracker

The issue is fixed for PreviewView TextureView mode. There is the problem on SurfaceView mode and suggest to use TextureView mode for ViewPager2 (PreviewView default is TextureView mode).

The fix will be included on CameraX May release.

This issue is still occuring on 1.1.0-rc01

Hi ,

Do you use PreviewView ? Can you try setting implementationMode to COMPATIBLE and try again ?

If issue still happens, it would be helpful go give more information or code snippet showing how you configure CameraX with ViewPager2.

Scott

The fix was only for TextureView (COMPATIBLE mode).

Reopen it to track the SurfaceView issue.

In COMPATIBLE mode when the fragment is off screen the camera is still bound and active and running through the use cases. But when the fragment is back into view it works perfect. I'm not sure if this matters but I'm using ViewPager2 inside a Fragment and not inside an Activity

Below is the camera binding

@SuppressLint("UnsafeOptInUsageError", "RestrictedApi")
    private fun startCamera() {
        // Create an instance of the ProcessCameraProvider,
        // which will be used to bind the use cases to a lifecycle owner.
        val cameraProviderFuture = ProcessCameraProvider.getInstance(requireContext())

        // Add a listener to the cameraProviderFuture.
        // The first argument is a Runnable, which will be where the magic actually happens.
        // The second argument (way down below) is an Executor that runs on the main thread.
        cameraProviderFuture.addListener({
            // Add a ProcessCameraProvider, which binds the lifecycle of your camera to
            // the LifecycleOwner within the application's life.
            cameraProvider = cameraProviderFuture.get()
            // Initialize the Preview object, get a surface provider from your PreviewView,
            // and set it on the preview instance.
            val preview = Preview.Builder()
                .build().also {
                    it.setSurfaceProvider(
                        binding.previewView.surfaceProvider
                    )
                }
            // Setup the ImageAnalyzer for the ImageAnalysis use case
            val builder = ImageAnalysis.Builder()
            val ext: Camera2Interop.Extender<*> = Camera2Interop.Extender(builder)
            ext.setCaptureRequestOption(
                CaptureRequest.CONTROL_AE_MODE,
                CaptureRequest.CONTROL_AE_MODE_ON
            )
            ext.setCaptureRequestOption(
                CaptureRequest.CONTROL_AF_MODE,
                CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_VIDEO
            )
            ext.setCaptureRequestOption(
                CaptureRequest.CONTROL_AWB_MODE,
                CaptureRequest.CONTROL_AWB_MODE_AUTO
            )
            ext.setCaptureRequestOption(
                CaptureRequest.CONTROL_AE_ANTIBANDING_MODE,
                CaptureRequest.CONTROL_AE_ANTIBANDING_MODE_AUTO
            )
            ext.setCaptureRequestOption(
                CaptureRequest.COLOR_CORRECTION_MODE,
                CaptureRequest.COLOR_CORRECTION_MODE_FAST
            )
            ext.setCaptureRequestOption(
                CaptureRequest.COLOR_CORRECTION_ABERRATION_MODE,
                CaptureRequest.COLOR_CORRECTION_ABERRATION_MODE_HIGH_QUALITY
            )
            ext.setCaptureRequestOption(
                CaptureRequest.CONTROL_VIDEO_STABILIZATION_MODE,
                CaptureRequest.CONTROL_VIDEO_STABILIZATION_MODE_ON
            )
            ext.setCaptureRequestOption(
                CaptureRequest.LENS_OPTICAL_STABILIZATION_MODE,
                CaptureRequest.LENS_OPTICAL_STABILIZATION_MODE_ON
            )
            ext.setCaptureRequestOption(
                CaptureRequest.CONTROL_SCENE_MODE,
                CaptureRequest.CONTROL_SCENE_MODE_BARCODE
            )
            val imageAnalysis = builder
                .setTargetResolution(Size(1536, 2048))
                .setBackpressureStrategy(ImageAnalysis.STRATEGY_KEEP_ONLY_LATEST)
                .build()
                .also {
                    it.setAnalyzer(cameraExecutor, AcfLabelAnalyzer { barcodes ->
                        if (processing.compareAndSet(false, true)) {
                            handleScan2(barcodes)
                        }
                    })
                }

            // Select back camera
            val cameraSelector = CameraSelector.DEFAULT_BACK_CAMERA
            try {
                // Unbind any bound use cases before rebinding
                cameraProvider?.unbindAll()
                // Bind use cases to lifecycleOwner
                val useCaseGroup = UseCaseGroup.Builder()
                    .addUseCase(preview)
                    .addUseCase(imageAnalysis)
                    .build()
                camera = cameraProvider?.bindToLifecycle(requireParentFragment().viewLifecycleOwner, cameraSelector, useCaseGroup)

                val cameraControl = camera?.cameraControl

                cameraControl?.setLinearZoom(0.4f)
                cameraControl?.enableTorch(true)
            } catch (e: Exception) {
                Log.e("PreviewUseCase", "Binding failed! :(", e)
            }
        }, ContextCompat.getMainExecutor(requireContext()))
    }

Below is the ViewPager2 setup in the onViewCreated()

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        binding = FragmentCaptureTabsBinding.bind(view)

        adapter = ViewPagerAdapter(childFragmentManager, lifecycle)

        adapter.addFrag(CaptureFragment(), "Capture")
        adapter.addFrag(LostOrUnauthorizedFragment(), "Tab 2")
        binding.viewpager.adapter = adapter

        if (adapter.itemCount < 2) {
            binding.tablayout.visibility = View.GONE
        }

        TabLayoutMediator(binding.tablayout, binding.viewpager) { tab, position ->
            tab.text = adapter.getPageTitle(position)
        }.attach()
    }

To clarify, are you saying that the issue is fixed after setting COMPATIBLE mode Or are there still issues?

In COMPATIBLE mode and the fragment is off screen, onPause() called I would expect the camera to be paused unbinded.

In unconfigured mode same thing happens with camera being paused but when onResume() is called the PreviewView is black.

OK. So using Compatible mode does fix the black preview issue.

Regarding the behavior that camera is not stopped when onPaused. This is by design. CameraX only closes the camera when onStop happens. This make sense in the scenario of multi-window, For example, if apps is paused due to focus changes to another window, then camera can still be working and showing preview.

For the scenario of viewpager, it has the benefits of showing preview even when swiping the page.

If you really need to control the timing of camera open/close, you can refer to here to write your own custom LifecycleOwner. and bind with this custom lifecycleOwner instead. And then you can set the status to stopped when onPaused happens to make it stop the camera.

Scott