マルチカメラ API

/**
 * Helper class used to encapsulate a logical camera and two underlying
 * physical cameras
 */
data class DualCamera(val logicalId: String, val physicalId1: String, val physicalId2: String)

fun findDualCameras(manager: CameraManager, facing: Int? = null): List<DualCamera> {
    val dualCameras = MutableList<DualCamera>()

    // Iterate over all the available camera characteristics
    manager.cameraIdList.map {
        Pair(manager.getCameraCharacteristics(it), it)
    }.filter {
        // Filter by cameras facing the requested direction
        facing == null || it.first.get(CameraCharacteristics.LENS_FACING) == facing
    }.filter {
        // Filter by logical cameras
        // CameraCharacteristics.REQUEST_AVAILABLE_CAPABILITIES_LOGICAL_MULTI_CAMERA requires API >= 28
        it.first.get(CameraCharacteristics.REQUEST_AVAILABLE_CAPABILITIES)!!.contains(
            CameraCharacteristics.REQUEST_AVAILABLE_CAPABILITIES_LOGICAL_MULTI_CAMERA)
    }.forEach {
        // All possible pairs from the list of physical cameras are valid results
        // NOTE: There could be N physical cameras as part of a logical camera grouping
        // getPhysicalCameraIds() requires API >= 28
        val physicalCameras = it.first.physicalCameraIds.toTypedArray()
        for (idx1 in 0 until physicalCameras.size) {
            for (idx2 in (idx1 + 1) until physicalCameras.size) {
                dualCameras.add(DualCamera(
                    it.second, physicalCameras[idx1], physicalCameras[idx2]))
            }
        }
    }

    return dualCameras
}

/**
 * Helper class used to encapsulate a logical camera and two underlying
 * physical cameras
 */
final class DualCamera {
    final String logicalId;
    final String physicalId1;
    final String physicalId2;

    DualCamera(String logicalId, String physicalId1, String physicalId2) {
        this.logicalId = logicalId;
        this.physicalId1 = physicalId1;
        this.physicalId2 = physicalId2;
    }
}
List<DualCamera> findDualCameras(CameraManager manager, Integer facing) {
    List<DualCamera> dualCameras = new ArrayList<>();

    List<String> cameraIdList;
    try {
        cameraIdList = Arrays.asList(manager.getCameraIdList());
    } catch (CameraAccessException e) {
        e.printStackTrace();
        cameraIdList = new ArrayList<>();
    }

    // Iterate over all the available camera characteristics
    cameraIdList.stream()
            .map(id -> {
                try {
                    CameraCharacteristics characteristics = manager.getCameraCharacteristics(id);
                    return new Pair<>(characteristics, id);
                } catch (CameraAccessException e) {
                    e.printStackTrace();
                    return null;
                }
            })
            .filter(pair -> {
                // Filter by cameras facing the requested direction
                return (pair != null) &&
                        (facing == null || pair.first.get(CameraCharacteristics.LENS_FACING).equals(facing));
            })
            .filter(pair -> {
                // Filter by logical cameras
                // CameraCharacteristics.REQUEST_AVAILABLE_CAPABILITIES_LOGICAL_MULTI_CAMERA requires API >= 28
                IntPredicate logicalMultiCameraPred =
                        arg -> arg == CameraCharacteristics.REQUEST_AVAILABLE_CAPABILITIES_LOGICAL_MULTI_CAMERA;
                return Arrays.stream(pair.first.get(CameraCharacteristics.REQUEST_AVAILABLE_CAPABILITIES))
                        .anyMatch(logicalMultiCameraPred);
            })
            .forEach(pair -> {
                // All possible pairs from the list of physical cameras are valid results
                // NOTE: There could be N physical cameras as part of a logical camera grouping
                // getPhysicalCameraIds() requires API >= 28
                String[] physicalCameras = pair.first.getPhysicalCameraIds().toArray(new String[0]);
                for (int idx1 = 0; idx1 < physicalCameras.length; idx1++) {
                    for (int idx2 = idx1 + 1; idx2 < physicalCameras.length; idx2++) {
                        dualCameras.add(
                                new DualCamera(pair.second, physicalCameras[idx1], physicalCameras[idx2]));
                    }
                }
            });
    return dualCameras;
}

fun openDualCamera(cameraManager: CameraManager,
                       dualCamera: DualCamera,
                       // AsyncTask is deprecated beginning API 30
                       executor: Executor = AsyncTask.SERIAL_EXECUTOR,
                       callback: (CameraDevice) -> Unit) {

        // openCamera() requires API >= 28
        cameraManager.openCamera(
            dualCamera.logicalId, executor, object : CameraDevice.StateCallback() {
                override fun onOpened(device: CameraDevice) = callback(device)
                // Omitting for brevity...
                override fun onError(device: CameraDevice, error: Int) = onDisconnected(device)
                override fun onDisconnected(device: CameraDevice) = device.close()
            })
    }

void openDualCamera(CameraManager cameraManager,
                        DualCamera dualCamera,
                        Executor executor,
                        CameraDeviceCallback cameraDeviceCallback
    ) {

        // openCamera() requires API >= 28
        cameraManager.openCamera(dualCamera.logicalId, executor, new CameraDevice.StateCallback() {
            @Override
            public void onOpened(@NonNull CameraDevice cameraDevice) {
               cameraDeviceCallback.callback(cameraDevice);
            }

            @Override
            public void onDisconnected(@NonNull CameraDevice cameraDevice) {
                cameraDevice.close();
            }

            @Override
            public void onError(@NonNull CameraDevice cameraDevice, int i) {
                onDisconnected(cameraDevice);
            }
        });
    }

/**
 * Helper type definition that encapsulates 3 sets of output targets:
 *
 * 1. Logical camera
 * 2. First physical camera
 * 3. Second physical camera
 */
typealias DualCameraOutputs =
        Triple<MutableList<Surface>?, MutableList<Surface>?, MutableList<Surface>?>

fun createDualCameraSession(cameraManager: CameraManager,
                            dualCamera: DualCamera,
                            targets: DualCameraOutputs,
                            // AsyncTask is deprecated beginning API 30
                            executor: Executor = AsyncTask.SERIAL_EXECUTOR,
                            callback: (CameraCaptureSession) -> Unit) {

    // Create 3 sets of output configurations: one for the logical camera, and
    // one for each of the physical cameras.
    val outputConfigsLogical = targets.first?.map { OutputConfiguration(it) }
    val outputConfigsPhysical1 = targets.second?.map {
        OutputConfiguration(it).apply { setPhysicalCameraId(dualCamera.physicalId1) } }
    val outputConfigsPhysical2 = targets.third?.map {
        OutputConfiguration(it).apply { setPhysicalCameraId(dualCamera.physicalId2) } }

    // Put all the output configurations into a single flat array
    val outputConfigsAll = arrayOf(
        outputConfigsLogical, outputConfigsPhysical1, outputConfigsPhysical2)
        .filterNotNull().flatMap { it }

    // Instantiate a session configuration that can be used to create a session
    val sessionConfiguration = SessionConfiguration(
        SessionConfiguration.SESSION_REGULAR,
        outputConfigsAll, executor, object : CameraCaptureSession.StateCallback() {
            override fun onConfigured(session: CameraCaptureSession) = callback(session)
            // Omitting for brevity...
            override fun onConfigureFailed(session: CameraCaptureSession) = session.device.close()
        })

    // Open the logical camera using the previously defined function
    openDualCamera(cameraManager, dualCamera, executor = executor) {

        // Finally create the session and return using the callback
        it.createCaptureSession(sessionConfiguration)
    }
}

/**
 * Helper class definition that encapsulates 3 sets of output targets:
 * <p>
 * 1. Logical camera
 * 2. First physical camera
 * 3. Second physical camera
 */
final class DualCameraOutputs {
    private final List<Surface> logicalCamera;
    private final List<Surface> firstPhysicalCamera;
    private final List<Surface> secondPhysicalCamera;

    public DualCameraOutputs(List<Surface> logicalCamera, List<Surface> firstPhysicalCamera, List<Surface> third) {
        this.logicalCamera = logicalCamera;
        this.firstPhysicalCamera = firstPhysicalCamera;
        this.secondPhysicalCamera = third;
    }

    public List<Surface> getLogicalCamera() {
        return logicalCamera;
    }

    public List<Surface> getFirstPhysicalCamera() {
        return firstPhysicalCamera;
    }

    public List<Surface> getSecondPhysicalCamera() {
        return secondPhysicalCamera;
    }
}

interface CameraCaptureSessionCallback {
    void callback(CameraCaptureSession cameraCaptureSession);
}

void createDualCameraSession(CameraManager cameraManager,
                             DualCamera dualCamera,
                             DualCameraOutputs targets,
                             Executor executor,
                             CameraCaptureSessionCallback cameraCaptureSessionCallback) {

    // Create 3 sets of output configurations: one for the logical camera, and
    // one for each of the physical cameras.
    List<OutputConfiguration> outputConfigsLogical = targets.getLogicalCamera().stream()
            .map(OutputConfiguration::new)
            .collect(Collectors.toList());
    List<OutputConfiguration> outputConfigsPhysical1 = targets.getFirstPhysicalCamera().stream()
            .map(s -> {
                OutputConfiguration outputConfiguration = new OutputConfiguration(s);
                outputConfiguration.setPhysicalCameraId(dualCamera.physicalId1);
                return outputConfiguration;
            })
            .collect(Collectors.toList());
    List<OutputConfiguration> outputConfigsPhysical2 = targets.getSecondPhysicalCamera().stream()
            .map(s -> {
                OutputConfiguration outputConfiguration = new OutputConfiguration(s);
                outputConfiguration.setPhysicalCameraId(dualCamera.physicalId2);
                return outputConfiguration;
            })
            .collect(Collectors.toList());

    // Put all the output configurations into a single flat array
    List<OutputConfiguration> outputConfigsAll = Stream.of(
                    outputConfigsLogical, outputConfigsPhysical1, outputConfigsPhysical2
            )
            .filter(Objects::nonNull)
            .flatMap(Collection::stream)
            .collect(Collectors.toList());

    // Instantiate a session configuration that can be used to create a session
    SessionConfiguration sessionConfiguration = new SessionConfiguration(
            SessionConfiguration.SESSION_REGULAR,
            outputConfigsAll, executor, new CameraCaptureSession.StateCallback() {
        @Override
        public void onConfigured(@NonNull CameraCaptureSession cameraCaptureSession) {
            cameraCaptureSessionCallback.callback(cameraCaptureSession);
        }
        // Omitting for brevity...
        @Override
        public void onConfigureFailed(@NonNull CameraCaptureSession cameraCaptureSession) {
            cameraCaptureSession.getDevice().close();
        }
    });

    // Open the logical camera using the previously defined function
    openDualCamera(cameraManager, dualCamera, executor, (CameraDevice c) ->
            // Finally create the session and return using the callback
            c.createCaptureSession(sessionConfiguration));
}

fun findShortLongCameraPair(manager: CameraManager, facing: Int? = null): DualCamera? {

    return findDualCameras(manager, facing).map {
        val characteristics1 = manager.getCameraCharacteristics(it.physicalId1)
        val characteristics2 = manager.getCameraCharacteristics(it.physicalId2)

        // Query the focal lengths advertised by each physical camera
        val focalLengths1 = characteristics1.get(
            CameraCharacteristics.LENS_INFO_AVAILABLE_FOCAL_LENGTHS) ?: floatArrayOf(0F)
        val focalLengths2 = characteristics2.get(
            CameraCharacteristics.LENS_INFO_AVAILABLE_FOCAL_LENGTHS) ?: floatArrayOf(0F)

        // Compute the largest difference between min and max focal lengths between cameras
        val focalLengthsDiff1 = focalLengths2.maxOrNull()!! - focalLengths1.minOrNull()!!
        val focalLengthsDiff2 = focalLengths1.maxOrNull()!! - focalLengths2.minOrNull()!!

        // Return the pair of camera IDs and the difference between min and max focal lengths
        if (focalLengthsDiff1 < focalLengthsDiff2) {
            Pair(DualCamera(it.logicalId, it.physicalId1, it.physicalId2), focalLengthsDiff1)
        } else {
            Pair(DualCamera(it.logicalId, it.physicalId2, it.physicalId1), focalLengthsDiff2)
        }

        // Return only the pair with the largest difference, or null if no pairs are found
    }.maxByOrNull { it.second }?.first
}

// Utility functions to find min/max value in float[]
    float findMax(float[] array) {
        float max = Float.NEGATIVE_INFINITY;
        for(float cur: array)
            max = Math.max(max, cur);
        return max;
    }
    float findMin(float[] array) {
        float min = Float.NEGATIVE_INFINITY;
        for(float cur: array)
            min = Math.min(min, cur);
        return min;
    }

DualCamera findShortLongCameraPair(CameraManager manager, Integer facing) {
        return findDualCameras(manager, facing).stream()
                .map(c -> {
                    CameraCharacteristics characteristics1;
                    CameraCharacteristics characteristics2;
                    try {
                        characteristics1 = manager.getCameraCharacteristics(c.physicalId1);
                        characteristics2 = manager.getCameraCharacteristics(c.physicalId2);
                    } catch (CameraAccessException e) {
                        e.printStackTrace();
                        return null;
                    }

                    // Query the focal lengths advertised by each physical camera
                    float[] focalLengths1 = characteristics1.get(
                            CameraCharacteristics.LENS_INFO_AVAILABLE_FOCAL_LENGTHS);
                    float[] focalLengths2 = characteristics2.get(
                            CameraCharacteristics.LENS_INFO_AVAILABLE_FOCAL_LENGTHS);

                    // Compute the largest difference between min and max focal lengths between cameras
                    Float focalLengthsDiff1 = findMax(focalLengths2) - findMin(focalLengths1);
                    Float focalLengthsDiff2 = findMax(focalLengths1) - findMin(focalLengths2);

                    // Return the pair of camera IDs and the difference between min and max focal lengths
                    if (focalLengthsDiff1 < focalLengthsDiff2) {
                        return new Pair<>(new DualCamera(c.logicalId, c.physicalId1, c.physicalId2), focalLengthsDiff1);
                    } else {
                        return new Pair<>(new DualCamera(c.logicalId, c.physicalId2, c.physicalId1), focalLengthsDiff2);
                    }

                }) // Return only the pair with the largest difference, or null if no pairs are found
                .max(Comparator.comparing(pair -> pair.second)).get().first;
    }

val cameraManager: CameraManager = ...

// Get the two output targets from the activity / fragment
val surface1 = ...  // from SurfaceView
val surface2 = ...  // from SurfaceView

val dualCamera = findShortLongCameraPair(manager)!!
val outputTargets = DualCameraOutputs(
    null, mutableListOf(surface1), mutableListOf(surface2))

// Here you open the logical camera, configure the outputs and create a session
createDualCameraSession(manager, dualCamera, targets = outputTargets) { session ->

  // Create a single request which has one target for each physical camera
  // NOTE: Each target receive frames from only its associated physical camera
  val requestTemplate = CameraDevice.TEMPLATE_PREVIEW
  val captureRequest = session.device.createCaptureRequest(requestTemplate).apply {
    arrayOf(surface1, surface2).forEach { addTarget(it) }
  }.build()

  // Set the sticky request for the session and you are done
  session.setRepeatingRequest(captureRequest, null, null)
}

CameraManager manager = ...;

        // Get the two output targets from the activity / fragment
        Surface surface1 = ...;  // from SurfaceView
        Surface surface2 = ...;  // from SurfaceView

        DualCamera dualCamera = findShortLongCameraPair(manager, null);
                DualCameraOutputs outputTargets = new DualCameraOutputs(
                null, Collections.singletonList(surface1), Collections.singletonList(surface2));

        // Here you open the logical camera, configure the outputs and create a session
        createDualCameraSession(manager, dualCamera, outputTargets, null, (session) -> {
            // Create a single request which has one target for each physical camera
            // NOTE: Each target receive frames from only its associated physical camera
            CaptureRequest.Builder captureRequestBuilder;
            try {
                captureRequestBuilder = session.getDevice().createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
                Arrays.asList(surface1, surface2).forEach(captureRequestBuilder::addTarget);

                // Set the sticky request for the session and you are done
                session.setRepeatingRequest(captureRequestBuilder.build(), null, null);
            } catch (CameraAccessException e) {
                e.printStackTrace();
            }
        });

val cameraSession: CameraCaptureSession = ...

        // Use still capture template to build the capture request
        val captureRequest = cameraSession.device.createCaptureRequest(
            CameraDevice.TEMPLATE_STILL_CAPTURE
        )

        // Determine if this device supports distortion correction
        val characteristics: CameraCharacteristics = ...
        val supportsDistortionCorrection = characteristics.get(
            CameraCharacteristics.DISTORTION_CORRECTION_AVAILABLE_MODES
        )?.contains(
            CameraMetadata.DISTORTION_CORRECTION_MODE_HIGH_QUALITY
        ) ?: false

        if (supportsDistortionCorrection) {
            captureRequest.set(
                CaptureRequest.DISTORTION_CORRECTION_MODE,
                CameraMetadata.DISTORTION_CORRECTION_MODE_HIGH_QUALITY
            )
        }

        // Add output target, set other capture request parameters...

        // Dispatch the capture request
        cameraSession.capture(captureRequest.build(), ...)

CameraCaptureSession cameraSession = ...;

        // Use still capture template to build the capture request
        CaptureRequest.Builder captureRequestBuilder = null;
        try {
            captureRequestBuilder = cameraSession.getDevice().createCaptureRequest(
                    CameraDevice.TEMPLATE_STILL_CAPTURE
            );
        } catch (CameraAccessException e) {
            e.printStackTrace();
        }

        // Determine if this device supports distortion correction
        CameraCharacteristics characteristics = ...;
        boolean supportsDistortionCorrection = Arrays.stream(
                        characteristics.get(
                                CameraCharacteristics.DISTORTION_CORRECTION_AVAILABLE_MODES
                        ))
                .anyMatch(i -> i == CameraMetadata.DISTORTION_CORRECTION_MODE_HIGH_QUALITY);
        if (supportsDistortionCorrection) {
            captureRequestBuilder.set(
                    CaptureRequest.DISTORTION_CORRECTION_MODE,
                    CameraMetadata.DISTORTION_CORRECTION_MODE_HIGH_QUALITY
            );
        }

        // Add output target, set other capture request parameters...

        // Dispatch the capture request
        cameraSession.capture(captureRequestBuilder.build(), ...);