LazyStaggeredGridMeasurePolicy.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.OverscrollEffect
import androidx.compose.foundation.checkScrollableContainerConstraints
import androidx.compose.foundation.gestures.Orientation
import androidx.compose.foundation.layout.Arrangement
import androidx.compose.foundation.layout.PaddingValues
import androidx.compose.foundation.lazy.layout.LazyLayoutItemProvider
import androidx.compose.foundation.lazy.layout.LazyLayoutMeasureScope
import androidx.compose.runtime.Composable
import androidx.compose.runtime.remember
import androidx.compose.ui.unit.Constraints
import androidx.compose.ui.unit.Density
@Composable
@ExperimentalFoundationApi
internal fun rememberStaggeredGridMeasurePolicy(
state: LazyStaggeredGridState,
itemProvider: LazyLayoutItemProvider,
contentPadding: PaddingValues,
reverseLayout: Boolean,
orientation: Orientation,
verticalArrangement: Arrangement.Vertical,
horizontalArrangement: Arrangement.Horizontal,
slotSizesSums: Density.(Constraints) -> IntArray,
overscrollEffect: OverscrollEffect
): LazyLayoutMeasureScope.(Constraints) -> LazyStaggeredGridMeasureResult = remember(
state,
itemProvider,
contentPadding,
reverseLayout,
orientation,
verticalArrangement,
horizontalArrangement,
slotSizesSums,
overscrollEffect,
) {
{ constraints ->
checkScrollableContainerConstraints(
constraints,
orientation
)
val resolvedSlotSums = slotSizesSums(this, constraints)
// setup information for prefetch
state.laneWidthsPrefixSum = resolvedSlotSums
state.isVertical = orientation == Orientation.Vertical
measure(
state,
itemProvider,
resolvedSlotSums,
constraints,
isVertical = orientation == Orientation.Vertical,
beforeContentPadding = 0,
afterContentPadding = 0,
).also {
state.applyMeasureResult(it)
overscrollEffect.isEnabled = it.canScrollForward || it.canScrollBackward
}
}
}