170904(월) - RxJava2 (Infinite scroll with RxJava2, Kotlin)

RxJava2 (Infinite scroll with RxJava2, Kotlin)

Create 사용

Flowable.create({ emitter ->
    applicationInfoList
            .filter { !it.packageName.isNullOrEmpty() && it.icon != 0 }
            .filter { applicationInfoList.indexOf(it) in startIndex until startIndex + MAX_LOADING_APP_LENGTH }
            .forEach {
                emitter.onNext(App(it.packageName, it.icon, appListActivity.packageManager.getApplicationLabel(it).toString()))
            }

    appListStartIdx += MAX_LOADING_APP_LENGTH
}, BackpressureStrategy.BUFFER)

fromIteratorable 사용

Flowable.fromIterable(applicationInfoList)
        .filter { !it.packageName.isNullOrEmpty() && it.icon != 0 }
        .filter { applicationInfoList.indexOf(it) in startIndex until startIndex + MAX_LOADING_APP_LENGTH }
        .map { appInfo -> App(appInfo.packageName, appInfo.icon, appListActivity.packageManager.getApplicationLabel(appInfo).toString()) }
        .doOnSubscribe { appListStartIdx += MAX_LOADING_APP_LENGTH }
        .subscribeOn(Schedulers.io())
        .observeOn(AndroidSchedulers.mainThread())
        .onBackpressureBuffer()

addOnScrollListener

recyclerview_app_list_activity.addOnScrollListener(object : RecyclerView.OnScrollListener() {
    override fun onScrolled(recyclerView: RecyclerView?, dx: Int, dy: Int) {
        super.onScrolled(recyclerView, dx, dy)

        val totalItemCount = appListStaggeredGridLayoutManager.itemCount
        val visibleItemCount = appListStaggeredGridLayoutManager.childCount
        val pastVisibleItems = appListStaggeredGridLayoutManager.findFirstVisibleItemPositions(null)[0]

        if (visibleItemCount + pastVisibleItems + AppListPresenter.ADJUSTED_VALUE >= totalItemCount) {
            appListPresenter.getInstalledAppsByParts(appListPresenter.appListStartIdx).subscribe({ app -> appListAdapter.addApp(app) })
                    .let { if (totalItemCount == appListPresenter.applicationInfoList.size) it.dispose() }
        }
    }
})

---

개선

fromIteratorable 사용

override fun loadMoreImages(page: Long): Disposable = imageLocalDataSource
        .loadThumbImages()
        .buffer(15)
        .elementAt(page)
        .doOnSubscribe { imageListActivity.isMoreLoading = true }
        .subscribeOn(Schedulers.io())
        .observeOn(AndroidSchedulers.mainThread())
        .subscribe(
                {
                    imageListActivity.apply {
                        addImagesToRecyclerView(it)
                        isMoreLoading = false
                    }
                },
                {
                    imageListActivity.isMoreLoading = false

                    Log.e("$javaClass [loadMoreImages()] : ", "${it.printStackTrace()}")
                },
                { imageListActivity.isMoreLoading = false })

OnScrollListener

override fun onScrollAndMoreListener() =
        object : RecyclerView.OnScrollListener() {
            override fun onScrolled(recyclerView: RecyclerView?, dx: Int, dy: Int) {
                super.onScrolled(recyclerView, dx, dy)

                if (isMoreLoading) return

                imageListGridLayoutManager.apply {
                    if (childCount + findFirstVisibleItemPositions(null).first() + ImageViewerConstant.PLACEHOLDER_DISTANCE >= itemCount) {
                        compositeDisposables.add(imageListPresenter.loadMoreImages(page++))
                    }
                }
            }
        }