LazySemantics.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
import androidx.compose.runtime.State
import androidx.compose.ui.Modifier
import androidx.compose.ui.semantics.CollectionInfo
import androidx.compose.ui.semantics.collectionInfo
import androidx.compose.ui.semantics.indexForKey
import androidx.compose.ui.semantics.scrollToIndex
import androidx.compose.ui.semantics.semantics
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.launch
internal fun Modifier.lazyListSemantics(
stateOfItemsProvider: State<LazyListItemsProvider>,
state: LazyListState,
coroutineScope: CoroutineScope,
isVertical: Boolean
): Modifier {
return semantics {
indexForKey { needle ->
val key = stateOfItemsProvider.value::getKey
for (index in 0 until stateOfItemsProvider.value.itemsCount) {
if (key(index) == needle) {
return@indexForKey index
}
}
-1
}
scrollToIndex { index ->
require(index >= 0 && index < stateOfItemsProvider.value.itemsCount) {
"Can't scroll to index $index, it is out of bounds [0, ${stateOfItemsProvider
.value.itemsCount})"
}
coroutineScope.launch {
state.scrollToItem(index)
}
true
}
collectionInfo = CollectionInfo(
rowCount = if (isVertical) -1 else 1,
columnCount = if (isVertical) 1 else -1
)
}
}