LazyListScopeImpl.kt
/*
* Copyright 2021 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.list
import androidx.compose.foundation.ExperimentalFoundationApi
import androidx.compose.foundation.lazy.LazyItemScope
import androidx.compose.foundation.lazy.LazyListScope
import androidx.compose.foundation.lazy.layout.IntervalList
import androidx.compose.foundation.lazy.layout.MutableIntervalList
import androidx.compose.runtime.Composable
internal class LazyListScopeImpl : LazyListScope {
private val _intervals = MutableIntervalList<LazyListIntervalContent>()
val intervals: IntervalList<LazyListIntervalContent> = _intervals
private var _headerIndexes: MutableList<Int>? = null
val headerIndexes: List<Int> get() = _headerIndexes ?: emptyList()
override fun items(
count: Int,
key: ((index: Int) -> Any)?,
contentType: (index: Int) -> Any?,
itemContent: @Composable LazyItemScope.(index: Int) -> Unit
) {
_intervals.add(
count,
LazyListIntervalContent(
key = key,
type = contentType,
content = { index -> @Composable { itemContent(index) } }
)
)
}
override fun item(key: Any?, contentType: Any?, content: @Composable LazyItemScope.() -> Unit) {
_intervals.add(
1,
LazyListIntervalContent(
key = if (key != null) { _: Int -> key } else null,
type = { contentType },
content = { @Composable { content() } }
)
)
}
@ExperimentalFoundationApi
override fun stickyHeader(
key: Any?,
contentType: Any?,
content: @Composable LazyItemScope.() -> Unit
) {
val headersIndexes = _headerIndexes ?: mutableListOf<Int>().also {
_headerIndexes = it
}
headersIndexes.add(_intervals.totalSize)
item(key, contentType, content)
}
}
internal class LazyListIntervalContent(
val key: ((index: Int) -> Any)?,
val type: ((index: Int) -> Any?),
val content: LazyItemScope.(index: Int) -> @Composable () -> Unit
)