CurvedContainer.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.wear.compose.foundation
import androidx.compose.foundation.layout.LayoutScopeMarker
import androidx.compose.runtime.Composable
import androidx.compose.ui.graphics.drawscope.DrawScope
import androidx.compose.ui.layout.Measurable
import androidx.compose.ui.layout.MeasureScope
import androidx.compose.ui.layout.Placeable
/**
* Layout scope used for curved containers.
* This is the base of a DSL that specifies what components can be added to a curved layout.
*/
@LayoutScopeMarker
public class CurvedScope internal constructor(
internal val curvedLayoutDirection: CurvedLayoutDirection
) {
internal val nodes = mutableListOf<CurvedChild>()
internal fun add(node: CurvedChild, modifier: CurvedModifier) {
nodes.add(modifier.wrap(node))
}
}
/**
* Base class for sub-layouts
*/
internal abstract class ContainerChild(
curvedLayoutDirection: CurvedLayoutDirection,
internal val reverseLayout: Boolean,
contentBuilder: CurvedScope.() -> Unit
) : CurvedChild() {
private val curvedContainerScope = CurvedScope(curvedLayoutDirection).apply(contentBuilder)
internal val children get() = curvedContainerScope.nodes
internal val childrenInLayoutOrder get() = children.indices.map { ix ->
children[if (reverseLayout) children.size - 1 - ix else ix]
}
@Composable
override fun SubComposition() {
children.forEach {
it.SubComposition()
}
}
override fun MeasureScope.initializeMeasure(
measurables: List<Measurable>,
index: Int
) = children.fold(index) { currentIndex, node ->
with(node) {
initializeMeasure(measurables, currentIndex)
}
}
override fun DrawScope.draw() = children.forEach { with(it) { draw() } }
override fun (Placeable.PlacementScope).placeIfNeeded() {
children.forEach { with(it) { placeIfNeeded() } }
}
}