Lifecycle-aware CameraView implementation

LifecycleCameraView.kt

import android.arch.lifecycle.Lifecycle
import android.arch.lifecycle.LifecycleObserver
import android.arch.lifecycle.LifecycleOwner
import android.arch.lifecycle.OnLifecycleEvent
import android.content.Context
import android.util.AttributeSet
import com.wonderkiln.camerakit.*

/**
 * Lifecycle aware view subclass of CameraView to allow automatic starting and stopping on lifecycle
 * events
 */
class LifecycleCameraView(context: Context, attributeSet: AttributeSet): CameraView(context, attributeSet), LifecycleObserver {

    var isStopped = true
        private set

    private var lifecycle: Lifecycle? = null

    fun init(owner: LifecycleOwner) {
        lifecycle = owner.lifecycle
        owner.lifecycle.addObserver(this)
    }

    @OnLifecycleEvent(Lifecycle.Event.ON_RESUME)
    fun onResume() {
        if (isStopped) {
            this.start()
        }
    }

    @OnLifecycleEvent(Lifecycle.Event.ON_PAUSE)
    fun onPause() {
        if (!isStopped) {
            this.stop()
        }
    }

    override fun stop() {
        if (lifecycle?.currentState?.isAtLeast(Lifecycle.State.CREATED) == true) {
            super.stop()
            isStopped = true
        }
    }

    override fun start() {
        if (lifecycle?.currentState?.isAtLeast(Lifecycle.State.CREATED) == true) {
            super.start()
            isStopped = false
        }
    }

    fun onPictureTaken(callback: (jepg: ByteArray) -> Unit) {
        this.addCameraKitListener(object: CameraKitEventListener {
            override fun onVideo(p0: CameraKitVideo?) {}

            override fun onEvent(p0: CameraKitEvent?) {}

            override fun onImage(image: CameraKitImage?) {
                image?.jpeg?.let(callback)
            }

            override fun onError(p0: CameraKitError?) {}
        })
    }
}