LazyStaggeredGridItemProvider.kt
/*
* Copyright 2022 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package androidx.compose.foundation.lazy.staggeredgrid
import androidx.compose.foundation.ExperimentalFoundationApi
import androidx.compose.foundation.lazy.layout.DelegatingLazyLayoutItemProvider
import androidx.compose.foundation.lazy.layout.LazyLayoutItemProvider
import androidx.compose.foundation.lazy.layout.LazyPinnableContainerProvider
import androidx.compose.foundation.lazy.layout.rememberLazyNearestItemsRangeState
import androidx.compose.runtime.Composable
import androidx.compose.runtime.derivedStateOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.rememberUpdatedState
@OptIn(ExperimentalFoundationApi::class)
internal interface LazyStaggeredGridItemProvider : LazyLayoutItemProvider {
val spanProvider: LazyStaggeredGridSpanProvider
}
@Composable
@ExperimentalFoundationApi
internal fun rememberStaggeredGridItemProvider(
state: LazyStaggeredGridState,
content: LazyStaggeredGridScope.() -> Unit,
): LazyStaggeredGridItemProvider {
val latestContent = rememberUpdatedState(content)
val nearestItemsRangeState = rememberLazyNearestItemsRangeState(
firstVisibleItemIndex = { state.firstVisibleItemIndex },
slidingWindowSize = { 90 },
extraItemCount = { 200 }
)
return remember(state) {
val itemProviderState = derivedStateOf {
val scope = LazyStaggeredGridScopeImpl().apply(latestContent.value)
object : LazyLayoutItemProvider by LazyLayoutItemProvider(
scope.intervals,
nearestItemsRangeState.value,
itemContent = { interval, index ->
LazyPinnableContainerProvider(state.pinnedItems, index) {
interval.value.item.invoke(
LazyStaggeredGridItemScopeImpl,
index - interval.startIndex
)
}
}
), LazyStaggeredGridItemProvider {
override val spanProvider = LazyStaggeredGridSpanProvider(scope.intervals)
}
}
object : LazyLayoutItemProvider by DelegatingLazyLayoutItemProvider(itemProviderState),
LazyStaggeredGridItemProvider {
override val spanProvider get() = itemProviderState.value.spanProvider
}
}
}