Create carousel to display images on the home screen

package io.eelo.appinstaller.home

import android.arch.lifecycle.Observer

import android.arch.lifecycle.ViewModelProviders

import android.content.Context

import android.graphics.Bitmap

import android.os.Bundle

import android.os.Handler

import android.support.v4.app.Fragment

import android.support.v4.view.ViewPager

import android.view.LayoutInflater

import android.view.View

import android.view.ViewGroup

import io.eelo.appinstaller.R

import io.eelo.appinstaller.home.viewmodel.HomeViewModel

import android.widget.Scroller

class HomeFragment : Fragment() {

    private lateinit var homeViewModel: HomeViewModel

    private lateinit var imageCarousel: ViewPager

    private var imagesList = ArrayList<Bitmap>()

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {

        return inflater.inflate(R.layout.fragment_home, container, false)

        val view = inflater.inflate(R.layout.fragment_home, container, false)

        homeViewModel = ViewModelProviders.of(activity!!).get(HomeViewModel::class.java)

        imageCarousel = view.findViewById(R.id.image_carousel)

        imageCarousel.visibility = View.GONE

        val imageCarouselAdapter = ImageCarouselAdapter(context!!, imagesList)

        // Initialise the image carousel

        val scroller = ViewPager::class.java.getDeclaredField("mScroller")

        scroller.isAccessible = true

        val imageCarouselScroller = ImageCarouselScroller(context!!)

        scroller.set(imageCarousel, imageCarouselScroller)

        imageCarousel.adapter = imageCarouselAdapter

        homeViewModel.loadCarouselImages()

        // Bind to the list of images for the carousel

        homeViewModel.getCarouselImages().observe(this, Observer {

            imagesList.clear()

            imagesList.addAll(homeViewModel.getCarouselImages().value!!)

            imageCarouselAdapter.notifyDataSetChanged()

            imageCarousel.visibility = View.VISIBLE

            imageCarousel.setCurrentItem(0, false)

            ImageCarouselTimer(((imageCarouselAdapter.count - 1) * 4000).toLong(), 4000).start()

        })

        return view

    }

    private inner class ImageCarouselTimer(private var millisInFuture: Long, private val countDownInterval: Long) {

        fun start() {

            val handler = Handler()

            val counter = object : Runnable {

                override fun run() {

                    if (millisInFuture <= 0) {

                        imageCarousel.setCurrentItem(0, true)

                    } else {

                        imageCarousel.setCurrentItem(imageCarousel.currentItem + 1, true)

                        millisInFuture -= countDownInterval

                        handler.postDelayed(this, countDownInterval)

                    }

                }

            }

            handler.postDelayed(counter, countDownInterval)

        }

    }

    // Custom scroller to reduce scrolling animation speed of view pager

    private inner class ImageCarouselScroller(context: Context) : Scroller(context) {

        private val mDuration = 2000

        override fun startScroll(startX: Int, startY: Int, dx: Int, dy: Int, duration: Int) {

            super.startScroll(startX, startY, dx, dy, mDuration)

        }

        override fun startScroll(startX: Int, startY: Int, dx: Int, dy: Int) {

            super.startScroll(startX, startY, dx, dy, mDuration)

        }

    }

}

package io.eelo.appinstaller.home

import android.content.Context

import android.graphics.Bitmap

import android.support.v4.view.PagerAdapter

import android.view.LayoutInflater

import android.view.View

import android.view.ViewGroup

import android.widget.ImageView

import android.widget.LinearLayout

import io.eelo.appinstaller.R

class ImageCarouselAdapter(context: Context, private val images: ArrayList<Bitmap>) : PagerAdapter() {

    private val layoutInflater = context.getSystemService(Context.LAYOUT_INFLATER_SERVICE) as LayoutInflater

    override fun isViewFromObject(view: View, `object`: Any): Boolean {

        return view == `object` as LinearLayout

    }

    override fun getCount(): Int {

        return images.size

    }

    override fun instantiateItem(container: ViewGroup, position: Int): Any {

        val itemView = layoutInflater.inflate(R.layout.image_carousel_item, container, false)

        val imageView = itemView.findViewById(R.id.image) as ImageView

        imageView.setImageBitmap(images[position])

        container.addView(itemView)

        return itemView

    }

    override fun destroyItem(container: ViewGroup, position: Int, `object`: Any) {

        container.removeView(`object` as LinearLayout)

    }

}

package io.eelo.appinstaller.home.model

import android.arch.lifecycle.MutableLiveData

import android.graphics.Bitmap

class HomeModel : HomeModelInterface {

    val imagesList = MutableLiveData<ArrayList<Bitmap>>()

    init {

        if (imagesList.value == null) {

            imagesList.value = ArrayList()

        }

    }

    override fun loadCarouselImages() {

        // TODO Load carousel images

    }

}

package io.eelo.appinstaller.home.model

interface HomeModelInterface {

    fun loadCarouselImages()

}

package io.eelo.appinstaller.home.viewModel

class HomeViewModel : HomeViewModelInterface {

}

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