LazyStaggeredGridSpan.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.IntervalList
import androidx.compose.foundation.lazy.staggeredgrid.StaggeredGridItemSpan.Companion.FullLine
/**
* Span defines a number of lanes (columns in vertical grid/rows in horizontal grid) for
* staggered grid items.
* Two variations of span are supported:
* - item taking a single lane ([SingleLane]);
* - item all lanes in line ([FullLine]).
* By default, staggered grid uses [SingleLane] for all items.
*/
@ExperimentalFoundationApi
class StaggeredGridItemSpan private constructor(internal val value: Int) {
companion object {
/**
* Force item to occupy whole line in cross axis.
*/
val FullLine = StaggeredGridItemSpan(0)
/**
* Force item to use a single lane.
*/
val SingleLane = StaggeredGridItemSpan(1)
}
}
@OptIn(ExperimentalFoundationApi::class)
internal class LazyStaggeredGridSpanProvider(
val intervals: IntervalList<LazyStaggeredGridIntervalContent>
) {
fun isFullSpan(itemIndex: Int): Boolean {
if (itemIndex !in 0 until intervals.size) return false
intervals[itemIndex].run {
val span = value.span
val localIndex = itemIndex - startIndex
return span != null && span(localIndex) === FullLine
}
}
}