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    <style name="FullscreenTheme" parent="AppTheme.NoActionBar">
        <item name="android:actionBarStyle">@style/FullscreenActionBarStyle</item>
        <item name="android:windowActionBarOverlay">true</item>
        <item name="android:windowBackground">@null</item>
        <item name="metaButtonBarStyle">?android:attr/buttonBarStyle</item>
        <item name="metaButtonBarButtonStyle">?android:attr/buttonBarButtonStyle</item>
    </style>

    <style name="FullscreenActionBarStyle" parent="Widget.AppCompat.ActionBar">
        <item name="android:background">@color/blackOverlay</item>
    </style>

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/coordinator"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".QuizActivity">

    <android.support.v4.view.ViewPager
        android:id="@+id/viewPager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@android:color/black" />
        
    // It's important, that toolbar is lower in code than content.
    // It'll make it appeare over content

    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/appBar"
        android:background="@android:color/transparent"
        android:theme="@style/AppTheme.AppBarOverlay"
        app:elevation="0dp">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="@color/blackOverlay" />

    </android.support.design.widget.AppBarLayout>

</android.support.design.widget.CoordinatorLayout>

abstract class FullscreenBaseActivity : AppCompatActivity() {

    abstract var mContentView: View?
    abstract var mControlsView: View?

    private val mHideHandler = Handler()
    @SuppressLint("InlinedApi")
    private val mHidePart2Runnable = Runnable {
        // Delayed removal of status and navigation bar

        // Note that some of these constants are new as of API 16 (Jelly Bean)
        // and API 19 (KitKat). It is safe to use them, as they are inlined
        // at compile-time and do nothing on earlier devices.
        mContentView?.systemUiVisibility = View.SYSTEM_UI_FLAG_LOW_PROFILE or
                View.SYSTEM_UI_FLAG_FULLSCREEN or
                View.SYSTEM_UI_FLAG_LAYOUT_STABLE or
                View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY or
                View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION or
                View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
    }
    private val mShowPart2Runnable = Runnable {
        // Delayed display of UI elements
        showActionBar()
    }
    private var mVisible: Boolean = false
    private val mHideRunnable = Runnable { hide() }
    /**
     * Touch listener to use for in-layout UI controls to delay hiding the
     * system UI. This is to prevent the jarring behavior of controls going away
     * while interacting with activity UI.
     */
    private val mDelayHideTouchListener = View.OnTouchListener { view, motionEvent ->
        if (AUTO_HIDE) {
            delayedHide(AUTO_HIDE_DELAY_MILLIS)
        }
        false
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        val myDecorView = window.decorView
        myDecorView.systemUiVisibility = View.SYSTEM_UI_FLAG_LAYOUT_STABLE or View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            window.addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS)
            window.statusBarColor = ContextCompat.getColor(this, R.color.blackOverlayDark)
        }

        mVisible = true

        // Upon interacting with UI controls, delay any scheduled hide()
        // operations to prevent the jarring behavior of controls going away
        // while interacting with the UI.
//        findViewById(R.id.dummy_button).setOnTouchListener(mDelayHideTouchListener)
    }

    override fun onPostCreate(savedInstanceState: Bundle?) {
        super.onPostCreate(savedInstanceState)

        // Trigger the initial hide() shortly after the activity has been
        // created, to briefly hint to the user that UI controls
        // are available.
        delayedHide(100)
    }

    // Important method. Call it in onCreate()
    fun setUpToolbar(toolbar: Toolbar, title: String) {

        setSupportActionBar(toolbar)
        supportActionBar?.setDisplayHomeAsUpEnabled(true)
        supportActionBar?.title = title
        val lp = toolbar.layoutParams as AppBarLayout.LayoutParams
        lp.setMargins(0, getStatusBarHeight(), 0, 0)
    }

    private fun getStatusBarHeight(): Int {
        var result = 0
        val resourceId = resources.getIdentifier("status_bar_height", "dimen", "android")
        if (resourceId > 0) {
            result = resources.getDimensionPixelSize(resourceId)
        }
        return result
    }

    fun toggle() {
        if (mVisible) {
            hide()
        } else {
            show()
        }
    }

    fun hide() {
        // Hide UI first
        hideActionBar()
        mControlsView?.visibility = View.GONE
        mVisible = false

        // Schedule a runnable to remove the status and navigation bar after a delay
        mHideHandler.removeCallbacks(mShowPart2Runnable)
        mHideHandler.postDelayed(mHidePart2Runnable, UI_ANIMATION_DELAY.toLong())
    }

    @SuppressLint("InlinedApi")
    fun show() {
        // Show the system bar
        mContentView?.systemUiVisibility = View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN or View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
        mVisible = true

        // Schedule a runnable to display UI elements after a delay
        mHideHandler.removeCallbacks(mHidePart2Runnable)
        mHideHandler.postDelayed(mShowPart2Runnable, UI_ANIMATION_DELAY.toLong())
        if (AUTO_HIDE) {
            delayedHide(AUTO_HIDE_DELAY_MILLIS)
        }
    }

    /**
     * Schedules a call to hide() in [delay] milliseconds, canceling any
     * previously scheduled calls.
     */
    fun delayedHide(delayMillis: Int) {
        mHideHandler.removeCallbacks(mHideRunnable)
        mHideHandler.postDelayed(mHideRunnable, delayMillis.toLong())
    }

    private fun hideActionBar() {
        val ab = supportActionBar
        if (ab != null && ab.isShowing) {
            if (appBar != null) {
                appBar.animate().translationY(-appBar.height.toFloat()).setDuration(200L)
                        .withEndAction({ ab.hide() }).start()
            } else ab.hide()
        }
    }

    private fun showActionBar() {
        val ab = supportActionBar
        if (ab != null && !ab.isShowing) {
            ab.show()
            if (appBar != null) {
                appBar.animate().translationY(0f).setDuration(200L).start()
            }
        }
    }

    companion object {
        /**
         * Whether or not the system UI should be auto-hidden after
         * [.AUTO_HIDE_DELAY_MILLIS] milliseconds.
         */
        private val AUTO_HIDE = true

        /**
         * If [.AUTO_HIDE] is set, the number of milliseconds to wait after
         * user interaction before hiding the system UI.
         */
        private val AUTO_HIDE_DELAY_MILLIS = 3000

        /**
         * Some older devices needs a small delay between UI widget updates
         * and a change of the status and navigation bar.
         */
        private val UI_ANIMATION_DELAY = 200
    }
}

import android.annotation.SuppressLint
import android.os.Build
import android.os.Bundle
import android.os.Handler
import android.support.design.widget.AppBarLayout
import android.support.v4.content.ContextCompat
import android.support.v4.view.ViewPager
import android.support.v7.app.AppCompatActivity
import android.util.Log
import android.view.View
import android.view.WindowManager
import kotlinx.android.synthetic.main.fragment_game.*
import us.kostenko.mnemonikon.R
import us.kostenko.mnemonikon.codes.utility.Image
import java.util.Collections.shuffle
import java.util.concurrent.TimeUnit


/**
 * An example full-screen activity that shows and hides the system UI (i.e.
 * status bar and navigation/system bar) with user interaction.
 */

val EXTRA_IMAGES = "extraImages"

class FullscreenActivity : AppCompatActivity() {

    private lateinit var images: java.util.ArrayList<Image>
    private lateinit var myViewPagerAdapter: GamePagerAdapter
    private var selectedPosition = 0

    var errors = 0
    var startTime: Long = 0
    var totalTime: Long = 0
    var itemsCount = 0
    var random = true

    //  page change listener
    internal var viewPagerPageChangeListener = object : ViewPager.SimpleOnPageChangeListener() {

        override fun onPageSelected(position: Int) {
            trackShowingTime()
        }
    }

    private val mHideHandler = Handler()
    @SuppressLint("InlinedApi")
    private val mHidePart2Runnable = Runnable {
        // Delayed removal of status and navigation bar

        // Note that some of these constants are new as of API 16 (Jelly Bean)
        // and API 19 (KitKat). It is safe to use them, as they are inlined
        // at compile-time and do nothing on earlier devices.
        viewPager!!.systemUiVisibility = View.SYSTEM_UI_FLAG_LOW_PROFILE or
                View.SYSTEM_UI_FLAG_FULLSCREEN or
                View.SYSTEM_UI_FLAG_LAYOUT_STABLE or
                View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY or
                View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION or
                View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
    }
    private val mShowPart2Runnable = Runnable {
        // Delayed display of UI elements
        showActionBar()
    }
    private var mVisible: Boolean = false
    private val mHideRunnable = Runnable { hide() }

    /**
     * Touch listener to use for in-layout UI controls to delay hiding the
     * system UI. This is to prevent the jarring behavior of controls going away
     * while interacting with activity UI.
     */

    private val mDelayHideTouchListener = View.OnTouchListener { view, motionEvent ->
        if (AUTO_HIDE) {
            delayedHide(AUTO_HIDE_DELAY_MILLIS)
        }
        false
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.fragment_game)

        val myDecorView = window.decorView
        myDecorView.systemUiVisibility = View.SYSTEM_UI_FLAG_LAYOUT_STABLE or View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            window.addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS)
            window.statusBarColor = ContextCompat.getColor(this, R.color.blackOverlayDark)
        }
        setSupportActionBar(toolbar)
        supportActionBar?.setDisplayHomeAsUpEnabled(true)
        toolbar.title = getString(R.id.codes_title)
        val lp = toolbar.layoutParams as AppBarLayout.LayoutParams
        lp.setMargins(0, getStatusBarHeight(), 0, 0)

        mVisible = true

        images = intent.getParcelableArrayListExtra(EXTRA_IMAGES)
        if (random) shuffle(images)
//        selectedPosition = intent.extras.getInt()

        myViewPagerAdapter = GamePagerAdapter(images, { isCorrect ->
            if (isCorrect) nextItem()
            else errors += 1
        }, { toggle() })
        viewPager.adapter = myViewPagerAdapter
        viewPager.addOnPageChangeListener(viewPagerPageChangeListener)

        setCurrentItem(selectedPosition)

        // Upon interacting with UI controls, delay any scheduled hide()
        // operations to prevent the jarring behavior of controls going away
        // while interacting with the UI.
//        findViewById(R.id.dummy_button).setOnTouchListener(mDelayHideTouchListener)
    }

    private fun setCurrentItem(position: Int) {
        viewPager.setCurrentItem(position, false)
    }

    private fun nextItem() {
        setCurrentItem(viewPager.currentItem + 1)
    }

    private fun trackShowingTime() {
        val finishTime: Long = System.nanoTime()

        if (itemsCount > 0) this.totalTime += TimeUnit.NANOSECONDS.toMillis(finishTime - startTime)
        Log.d("GameFragment", "trackShowingTime(), finishTime: $finishTime, startTime: $startTime, totalTime: ${this.totalTime}")
        startTime = finishTime
        itemsCount += 1
    }


    private fun getStatusBarHeight(): Int {
        var result = 0
        val resourceId = resources.getIdentifier("status_bar_height", "dimen", "android")
        if (resourceId > 0) {
            result = resources.getDimensionPixelSize(resourceId)
        }
        return result
    }

    fun hideActionBar() {
        val ab = supportActionBar
        if (ab != null && ab.isShowing) {
            if (appBar != null) {
                appBar.animate().translationY(-appBar.height.toFloat()).setDuration(200L)
                        .withEndAction({ ab.hide() }).start()
            } else ab.hide()
        }
    }

    fun showActionBar() {
        val ab = supportActionBar
        if (ab != null && !ab.isShowing) {
            ab.show()
            if (appBar != null) {
                appBar.animate().translationY(0f).setDuration(200L).start()
            }
        }
    }

    /* Not mine */

    override fun onPostCreate(savedInstanceState: Bundle?) {
        super.onPostCreate(savedInstanceState)

        // Trigger the initial hide() shortly after the activity has been
        // created, to briefly hint to the user that UI controls
        // are available.
        delayedHide(100)
    }

    private fun toggle() {
        if (mVisible) {
            hide()
        } else {
            show()
        }
    }

    private fun hide() {
        // Hide UI first
//        val actionBar = supportActionBar
//        actionBar?.hide()
        hideActionBar()
        mVisible = false

        // Schedule a runnable to remove the status and navigation bar after a delay
        mHideHandler.removeCallbacks(mShowPart2Runnable)
        mHideHandler.postDelayed(mHidePart2Runnable, UI_ANIMATION_DELAY.toLong())
    }

    @SuppressLint("InlinedApi")
    private fun show() {
        // Show the system bar
        viewPager.systemUiVisibility = View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN or View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
        mVisible = true

        // Schedule a runnable to display UI elements after a delay
        mHideHandler.removeCallbacks(mHidePart2Runnable)
        mHideHandler.postDelayed(mShowPart2Runnable, UI_ANIMATION_DELAY.toLong())
    }

    /**
     * Schedules a call to hide() in [delay] milliseconds, canceling any
     * previously scheduled calls.
     */
    private fun delayedHide(delayMillis: Int) {
        mHideHandler.removeCallbacks(mHideRunnable)
        mHideHandler.postDelayed(mHideRunnable, delayMillis.toLong())
    }

    companion object {
        /**
         * Whether or not the system UI should be auto-hidden after
         * [.AUTO_HIDE_DELAY_MILLIS] milliseconds.
         */
        private val AUTO_HIDE = true

        /**
         * If [.AUTO_HIDE] is set, the number of milliseconds to wait after
         * user interaction before hiding the system UI.
         */
        private val AUTO_HIDE_DELAY_MILLIS = 3000

        /**
         * Some older devices needs a small delay between UI widget updates
         * and a change of the status and navigation bar.
         */
        private val UI_ANIMATION_DELAY = 200
    }
}

        <activity
            android:name=".codes.game.FullscreenActivity"
            android:configChanges="orientation|keyboardHidden|screenSize"
            android:label="@string/title_activity_fullscreen"
            android:parentActivityName=".QuizActivity"
            android:theme="@style/FullscreenTheme">
        </activity>