multi-camera-api-1.kt

/**
* 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): Array<DualCamera> {
    val dualCameras = ArrayList<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
        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
        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.toTypedArray()
}