54 lines
1.8 KiB
Kotlin
54 lines
1.8 KiB
Kotlin
package dev.inmo.micro_utils.android.recyclerview
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import androidx.recyclerview.widget.*
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import kotlinx.coroutines.CoroutineScope
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import kotlinx.coroutines.flow.*
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@Suppress("NOTHING_TO_INLINE")
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private inline fun RecyclerView.LayoutManager.findLastVisibleItemPositionGetter(): (() -> Int)? = when (this) {
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is LinearLayoutManager -> ::findLastVisibleItemPosition
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is GridLayoutManager -> ::findLastVisibleItemPosition
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else -> null
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}
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fun RecyclerView.lastVisibleItemFlow(
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completingScope: CoroutineScope
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): Flow<Int> {
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val lastVisibleElementFun: () -> Int = layoutManager ?.findLastVisibleItemPositionGetter() ?: error("Currently supported only linear and grid layout manager")
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val lastVisibleFlow = MutableStateFlow(lastVisibleElementFun())
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addOnScrollListener(
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object : RecyclerView.OnScrollListener() {
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override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
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super.onScrolled(recyclerView, dx, dy)
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lastVisibleFlow.value = lastVisibleElementFun()
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}
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}.also { scrollListener ->
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lastVisibleFlow.onCompletion {
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removeOnScrollListener(scrollListener)
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}.launchIn(completingScope)
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}
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)
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return lastVisibleFlow.asStateFlow()
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}
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inline fun Flow<Int>.mapLeftItems(
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crossinline countGetter: () -> Int
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): Flow<Int> = map { countGetter() - it }
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inline fun Flow<Int>.mapRequireFilling(
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minimalLeftItems: Int,
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crossinline countGetter: () -> Int
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): Flow<Int> = mapLeftItems(countGetter).mapNotNull {
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if (it < minimalLeftItems) {
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it
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} else {
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null
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}
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}
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inline fun RecyclerView.mapRequireFilling(
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minimalLeftItems: Int,
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completingScope: CoroutineScope,
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crossinline countGetter: () -> Int
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): Flow<Int> = lastVisibleItemFlow(completingScope).mapRequireFilling(minimalLeftItems, countGetter)
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