1 /*
2  * Copyright 2022 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 package androidx.compose.ui.node
18 
19 import androidx.compose.ui.layout.IntrinsicMeasureScope
20 import androidx.compose.ui.layout.Measurable
21 import androidx.compose.ui.layout.MeasureScope
22 import androidx.compose.ui.node.LayoutNode.LayoutState
23 import androidx.compose.ui.util.fastMap
24 
25 internal interface MeasureScopeWithLayoutNode : MeasureScope {
26     val layoutNode: LayoutNode
27 }
28 
getChildrenOfVirtualChildrennull29 internal fun getChildrenOfVirtualChildren(scope: IntrinsicMeasureScope): List<List<Measurable>> {
30     val layoutNode = (scope as MeasureScopeWithLayoutNode).layoutNode
31     val lookahead = layoutNode.isInLookaheadPass()
32     return layoutNode.foldedChildren.fastMap {
33         if (lookahead) it.childLookaheadMeasurables else it.childMeasurables
34     }
35 }
36 
LayoutNodenull37 private fun LayoutNode.isInLookaheadPass(): Boolean {
38     return when (layoutState) {
39         LayoutState.LookaheadMeasuring,
40         LayoutState.LookaheadLayingOut -> true
41         LayoutState.Measuring,
42         LayoutState.LayingOut -> false
43         LayoutState.Idle -> {
44             // idle means intrinsics are being asked, we need to check the parent
45             requireNotNull(parent) { "no parent for idle node" }.isInLookaheadPass()
46         }
47     }
48 }
49