Adapter stops loading data if scrolled rapidly

[mehul4795]

I am using OneAdapter along with the Paging module to load images gradually from an API. The problem is that if I scroll the list rapidly the paging stops and no more data is loaded after 3-4 pages.

I am attaching the all the necessary code that I am using below.

HomeFragment

class HomeFragment : BaseFragment() {
private val viewModel by viewModel<HomeViewModel>() // Lazy inject ViewModel
private lateinit var homeAdapter: OneAdapter

override fun onCreateView(
    inflater: LayoutInflater, container: ViewGroup?,
    savedInstanceState: Bundle?
): View? {
    // Inflate the layout for this fragment
    return inflater.inflate(R.layout.fragment_home, container, false)
}

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
    super.onViewCreated(view, savedInstanceState)

    setupRecyclerView()
    observeImagesLiveData()
}

private fun setupRecyclerView() {
    rvHome.layoutManager = GridLayoutManager(context, 2)
    homeAdapter = OneAdapter()
        .attachItemModule(HomeItem(context!!))
        .attachPagingModule(HomePagingModule(viewModel))
        .attachTo(rvHome)

    homeAdapter.setItems(emptyList())
}

private fun observeImagesLiveData() {
    viewModel.getPicsumImages(1).observe(this, Observer { result ->
        when (result) {
            is Result.Loading -> {
                Timber.e("Loading")
            }

            is Result.Success<*> -> {
                val imagesList = result.data as List<PicsumPhoto>
                homeAdapter.add(imagesList)
            }

            is Result.Error -> {
                Timber.e(result.errorMessage)
            }
        }
    })
}}

ItemModule

class HomeItem(context: Context) : ItemModule<PicsumPhoto>() {

private val displayMetrics = context.resources.displayMetrics
private val columnWidth = displayMetrics.widthPixels / 2

override fun provideModuleConfig() = object : ItemModuleConfig() {
    override fun withLayoutResource() = R.layout.item_home
}

override fun onBind(model: PicsumPhoto, viewBinder: ViewBinder) {
    val mainImage: ImageView = viewBinder.findViewById(R.id.ivMainHomeItem)

    mainImage.apply {
        layoutParams.height = columnWidth
        layoutParams.width = columnWidth
        load(model.download_url)
    }

}}

PagingModule

class HomePagingModule(private val homeViewModel: HomeViewModel) : PagingModule() {

override fun provideModuleConfig() = object : PagingModuleConfig() {
    override fun withLayoutResource() = R.layout.load_more
    override fun withVisibleThreshold() = 3
}

override fun onLoadMore(currentPage: Int) {
    homeViewModel.getPicsumImages(currentPage + 1)
}}

[idanatz]

Hi mehul4795,

When the model does not implement the Diffable interface there is indeed a bug.

After testing some cases of fast scrolling with almost no delay I did not find any issue when the model is implementing the Diffable interface. Please be sure you are implementing the Diffable interface properly and tell me the bug still happens.

[mehul4795]

Hi, idanatz.

I followed the doc and implemented the Diffable interface but still facing the same problem :(

[idanatz]

Can you please share a minimal project that includes this bug, for me to test?

[mehul4795]

I am using OneAdapter in a demo project. I have added you as a Collaborator. Please check.

[idanatz]

Thanks, Found the bug, the logic behind the paging was incorrect when fast scrolling and using different layout managers other than Linear. Will be fixed in the next version 💪

[mehul4795]

That's great. Waiting for the next version. 😍