AlShevelev

class AudioPlayerUtil {
    private var mediaPlayer: MediaPlayer? = null

    /**
     *
     */
    fun stop() {
        if (mediaPlayer != null) {
            mediaPlayer!!.release()
            mediaPlayer = null

AlShevelev

abstract class VisualizerBase
@JvmOverloads
constructor(
    context: Context,
    attrs: AttributeSet? = null,
    defStyleAttr: Int = 0
) : View(context, attrs, defStyleAttr) {

    protected var audioBytes: ByteArray? = null
    private var visualizer: Visualizer? = null

AlShevelev

class WaveVisualizer
@JvmOverloads
constructor(
    context: Context,
    attrs: AttributeSet? = null,
    defStyleAttr: Int = 0
) : VisualizerBase(context, attrs, defStyleAttr) {

    private var paint: Paint
    private val waveformPath: Path = Path()

AlShevelev

/**
 * Reduces drag sensitivity of [ViewPager2] widget
 */
fun ViewPager2.reduceDragSensitivity() {
    val recyclerViewField = ViewPager2::class.java.getDeclaredField("mRecyclerView")
    recyclerViewField.isAccessible = true
    val recyclerView = recyclerViewField.get(this) as RecyclerView

    val touchSlopField = RecyclerView::class.java.getDeclaredField("mTouchSlop")
    touchSlopField.isAccessible = true

AlShevelev

class ShakeDetector : SensorEventListener {
    private companion object {
        const val SHAKE_THRESHOLD_GRAVITY = 2.7f          // In "Gs" (one Earth gravity unit)

        const val SHAKE_SLOP_TIME = 500                   // In [ms]
        const val SHAKE_COUNT_RESET_TIME = 3000
    }

    private var shakeListener: ((Int) -> Unit)? = null      // argument - shakes count in a row

AlShevelev

class FeedbackService : Service() {
    companion object {
        fun start(appContext: Context) {
            if(isRunning) {
                return
            }

            appContext.startService(Intent(appContext, FeedbackService::class.java))
        }

AlShevelev

class FeedbackService : Service() {
    companion object {
        fun start(appContext: Context) {
            if(isRunning) {
                return
            }

            appContext.startService(Intent(appContext, FeedbackService::class.java))
        }

AlShevelev

class ActivitiesMonitor(private val appContext: Context): Application.ActivityLifecycleCallbacks {
    private var activeActivities = 0

    init {
        (appContext as Application).registerActivityLifecycleCallbacks(this)
    }

    override fun onActivityPaused(activity: Activity?) {
        activeActivities--

AlShevelev

class App : Application() {

    private lateinit var activitiesMonitor: ActivitiesMonitor

    override fun onCreate() {
        super.onCreate()

        activitiesMonitor = ActivitiesMonitor(this.applicationContext)
    }
}

AlShevelev

class FeedbackFormActivity : AppCompatActivity() {
    companion object {
        private var isRunning = false

        fun start(context: Context) {
            if(isRunning) {
                return
            }

            Intent(context, FeedbackFormActivity::class.java)