/*
* 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.grid
import androidx.compose.animation.core.FiniteAnimationSpec
import androidx.compose.foundation.ExperimentalFoundationApi
import androidx.compose.foundation.lazy.GridItemSpan
import androidx.compose.foundation.lazy.LazyGridItemInfo
import androidx.compose.foundation.lazy.layout.LazyLayoutPlaceable
import androidx.compose.ui.layout.Placeable
import androidx.compose.ui.unit.IntOffset
import androidx.compose.ui.unit.IntSize
import androidx.compose.ui.unit.LayoutDirection
/**
* Represents one measured line of the lazy list. Each item on the line can in fact consist of
* multiple placeables if the user emit multiple layout nodes in the item callback.
*/
@OptIn(ExperimentalFoundationApi::class)
internal class LazyMeasuredLine constructor(
val index: LineIndex,
val firstItemIndex: ItemIndex,
private val crossAxisSizes: Array<Int>,
private val placeables: Array<Array<LazyLayoutPlaceable>>,
private val spans: List<GridItemSpan>,
val keys: Array<Any>,
private val isVertical: Boolean,
private val layoutDirection: LayoutDirection,
private val reverseLayout: Boolean,
private val beforeContentPadding: Int,
private val afterContentPadding: Int,
/**
* Spacing to be added after [mainAxisSize], in the main axis direction.
*/
private val mainAxisSpacing: Int,
private val crossAxisSpacing: Int
// private val placementAnimator: LazyListItemPlacementAnimator,
) {
/**
* Main axis size of the line - the max main axis size of the placeables.
*/
val mainAxisSize: Int
/**
* Sum of the main axis sizes of all the inner placeables and [mainAxisSpacing].
*/
val sizeWithSpacings: Int
init {
var maxMainAxis = 0
placeables.forEach { placeableArray ->
placeableArray.forEach {
val placeable = it.placeable
maxMainAxis =
maxOf(maxMainAxis, if (isVertical) placeable.height else placeable.width)
}
}
mainAxisSize = maxMainAxis
sizeWithSpacings = mainAxisSize + mainAxisSpacing
}
/**
* Whether this line contains any items.
*/
fun isEmpty() = placeables.isEmpty()
/**
* Calculates positions for the inner placeables at [offset] main axis position.
* If [reverseOrder] is true the inner placeables would be placed in the inverted order.
*/
fun position(
offset: Int,
layoutWidth: Int,
layoutHeight: Int
): List<LazyGridPositionedItem> {
var usedCrossAxis = 0
var usedSpan = 0
return placeables.mapIndexed { placeablesIndex, placeables ->
val wrappers = mutableListOf<LazyListPlaceableWrapper>()
val mainAxisLayoutSize = if (isVertical) layoutHeight else layoutWidth
val mainAxisOffset = if (reverseLayout) {
mainAxisLayoutSize - offset - mainAxisSize
} else {
offset
}
val crossAxisLayoutSize = if (isVertical) layoutWidth else layoutHeight
val crossAxisOffset = if (layoutDirection == LayoutDirection.Rtl && isVertical) {
crossAxisLayoutSize - usedCrossAxis - placeables.first().placeable.width
} else {
usedCrossAxis
}
val placeableOffset = if (isVertical) {
IntOffset(crossAxisOffset, mainAxisOffset)
} else {
IntOffset(mainAxisOffset, crossAxisOffset)
}
usedCrossAxis += crossAxisSizes[placeablesIndex] + crossAxisSpacing
val column = usedSpan
usedSpan += spans[placeablesIndex].currentLineSpan
var index = if (reverseLayout) placeables.lastIndex else 0
while (if (reverseLayout) index >= 0 else index < placeables.size) {
val it = placeables[index].placeable
val addIndex = if (reverseLayout) 0 else wrappers.size
wrappers.add(
addIndex,
LazyListPlaceableWrapper(placeableOffset, it, placeables[index].parentData)
)
if (reverseLayout) index-- else index++
}
LazyGridPositionedItem(
offset = placeableOffset,
index = firstItemIndex.value + placeablesIndex,
key = keys[placeablesIndex],
row = this@LazyMeasuredLine.index.value,
column = column,
size = if (isVertical) {
IntSize(crossAxisSizes[placeablesIndex], mainAxisSize)
} else {
IntSize(mainAxisSize, crossAxisSizes[placeablesIndex])
},
// sizeWithSpacings = sizeWithSpacings,
minMainAxisOffset = -if (!reverseLayout) {
beforeContentPadding
} else {
afterContentPadding
},
maxMainAxisOffset = mainAxisLayoutSize +
if (!reverseLayout) afterContentPadding else beforeContentPadding,
isVertical = isVertical,
wrappers = wrappers,
// placementAnimator = placementAnimator
)
}
}
}
@OptIn(ExperimentalFoundationApi::class)
internal class LazyGridPositionedItem(
override val offset: IntOffset,
override val index: Int,
override val key: Any,
override val row: Int,
override val column: Int,
override val size: IntSize,
// val sizeWithSpacings: Int,
private val minMainAxisOffset: Int,
private val maxMainAxisOffset: Int,
private val isVertical: Boolean,
private val wrappers: List<LazyListPlaceableWrapper>,
// private val placementAnimator: LazyListItemPlacementAnimator
) : LazyGridItemInfo {
val placeablesCount: Int get() = wrappers.size
fun getOffset(index: Int) = wrappers[index].offset
// fun getMainAxisSize(index: Int) = wrappers[index].placeable.mainAxisSize
@Suppress("UNCHECKED_CAST")
fun getAnimationSpec(index: Int) =
wrappers[index].parentData as? FiniteAnimationSpec<IntOffset>?
// val hasAnimations = run {
// repeat(placeablesCount) { index ->
// if (getAnimationSpec(index) != null) {
// return@run true
// }
// }
// false
// }
fun place(
scope: Placeable.PlacementScope,
) = with(scope) {
repeat(placeablesCount) { index ->
val placeable = wrappers[index].placeable
val minOffset = minMainAxisOffset - placeable.mainAxisSize
val maxOffset = maxMainAxisOffset
val offset =
// if (getAnimationSpec(index) != null) {
// placementAnimator.getAnimatedOffset(
// key, index, minOffset, maxOffset, getOffset(index)
// )
// } else {
getOffset(index)
// }
if (offset.mainAxis > minOffset && offset.mainAxis < maxOffset) {
if (isVertical) {
placeable.placeWithLayer(offset)
} else {
placeable.placeRelativeWithLayer(offset)
}
}
}
}
private val IntOffset.mainAxis get() = if (isVertical) y else x
private val Placeable.mainAxisSize get() = if (isVertical) height else width
}
internal class LazyListPlaceableWrapper(
val offset: IntOffset,
val placeable: Placeable,
val parentData: Any?
)