multi-camera-api-3.kt

/**
 * 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,
                            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 our previously defined function
    openDualCamera(cameraManager, dualCamera, executor = executor) {

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