Epoxy carousel how to move to the next item programmatically

Question

I have a requirement to display the Carousel Items and have buttons outside the Carousel items to go to the previous item and the next item. Given carousel items are the elements of the recycler view I should move to the next and previous position with the following methods but it seems to be not working

recyclerView.scrollToPosition(positionIndex) //or 
recyclerView.getLayoutManager().scrollToPosition(positionIndex)

I am not sure if there are any other callbacks to set the position as if a user is scrolling to the next item. Any help is highly appreciated

Answer 1

this is my code, This code will have an ellipsis that will scroll along the banner. and my banner can scroll automatically. You can try to apply it. Hope my code can help you.

//this is xml file

<com.yourdomain.epoxy.carousel.PagerSnapCarousel
    android:id="@+id/carouselBanner"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    app:layout_constraintBottom_toBottomOf="parent" />

<com.rd.PageIndicatorView
    android:id="@+id/dots_indicator"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/carouselBanner"
    app:piv_animationType="scale"
    app:piv_dynamicCount="true"
    app:piv_interactiveAnimation="true"
    app:piv_radius="@dimen/_5sdp"
    app:piv_orientation="horizontal" />

//And my epoxy model

data class MainPageGroupBannerModel(
var banner: MainPageBanner,
val callback: (NewsItem) -> Unit,
val callbackBanner: () -> Unit,

) : ViewBindingKotlinModel<ListItemMainPageBannerNewsBinding>(R.layout.list_item_main_page_banner_news) {
private var selectedPos: Int = 0

companion object {
    private const val AUTO_SLIDE_INTERVAL = 5000L
}

lateinit var carouselBannerItem: RecyclerView
lateinit var cyclicAdapterItem: CyclicAdapter
val handler = Handler(Looper.getMainLooper())

override fun ListItemMainPageBannerNewsBinding.bind() {

    carouselBannerItem = carouselBanner
    val mainPageBannerController = MainPageBannerController(callbackBanner,callback)
    val cyclicAdapter = CyclicAdapter(mainPageBannerController.adapter)
    cyclicAdapterItem = cyclicAdapter
    carouselBanner.apply {
        swapAdapter(
            when {
                (banner.news?.size ?: return) > 1 -> cyclicAdapter
                else -> mainPageBannerController.adapter
            },
            false
        )
    }
    mainPageBannerController.setData(banner)

    //ไข่ปลา
    dotsIndicator.count = cyclicAdapter.actualItemCount
    carouselBanner.clearOnScrollListeners()
    carouselBanner.addOnScrollListener(object : RecyclerView.OnScrollListener() {
        override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
            super.onScrolled(recyclerView, dx, dy)
            val firstPosition =
                (carouselBanner.layoutManager as? LinearLayoutManager)?.findFirstVisibleItemPosition()

            if (firstPosition != null && cyclicAdapter.actualItemCount != 0) {
                selectedPos = firstPosition % cyclicAdapter.actualItemCount
                dotsIndicator.selection = selectedPos
            }
        }

        override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
            super.onScrollStateChanged(recyclerView, newState)

        }
    })

    // Start auto-scrolling
    handler.postDelayed(autoSlideRunnable, AUTO_SLIDE_INTERVAL)
}

private val autoSlideRunnable = object : Runnable {
    override fun run() {
        carouselBannerItem?.let { banner ->
            val layoutManager = banner.layoutManager as LinearLayoutManager
            val currentPosition = layoutManager.findFirstVisibleItemPosition()
            val nextPosition = (currentPosition + 1) % cyclicAdapterItem.actualItemCount
            banner.smoothScrollToPosition(nextPosition)
            handler.postDelayed(this, AUTO_SLIDE_INTERVAL)
        }
    }
}

override fun unbind(view: View) {
    handler.removeCallbacks(autoSlideRunnable)
    super.unbind(view)
}

}