ShadowViewInfo.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.ui.tooling
import androidx.compose.ui.layout.LayoutInfo
import androidx.compose.ui.tooling.data.UiToolingDataApi
/**
* Version of [ViewInfo] that allows mutations. This is used to be able to re-attach different
* composition roots to the right tree.
*/
@OptIn(UiToolingDataApi::class)
private class ShadowViewInfo private constructor(
var parent: ShadowViewInfo?,
private val viewInfo: ViewInfo
) {
/** Constructor for root ShadowViewInfo nodes */
constructor(viewInfo: ViewInfo) : this(null, viewInfo)
private val _children: MutableList<ShadowViewInfo> =
viewInfo.children.map { ShadowViewInfo(this, it) }.toMutableList()
val children: List<ShadowViewInfo>
get() = _children
val layoutInfo: LayoutInfo?
get() = viewInfo.layoutInfo as? LayoutInfo
val allNodes: Sequence<ShadowViewInfo> = sequence {
yield(this@ShadowViewInfo)
children.flatMap { it.allNodes }.forEach { yield(it) }
}
fun setNewParent(parent: ShadowViewInfo) {
this.parent?._children?.remove(this)
parent._children.add(this)
this.parent = parent
}
fun findRoot(): ShadowViewInfo =
if (this.parent == null)
this
else
this.parent!!.findRoot()
fun toViewInfo(): ViewInfo = ViewInfo(
viewInfo.fileName,
viewInfo.lineNumber,
viewInfo.bounds,
viewInfo.location,
_children.map { it.toViewInfo() },
viewInfo.layoutInfo
)
}
/**
* Takes a number of composition roots and stitches them using the [LayoutInfo] information
* available. Ideally, if all composition roots are related, this method will return a list
* containing a list with a single element that will have all the input roots attached.
*/
internal fun stitchTrees(allViewInfoRoots: List<ViewInfo>): List<ViewInfo> {
if (allViewInfoRoots.size < 2) return allViewInfoRoots
// Convert trees info shadow mutable trees
val shadowTreeRoots = allViewInfoRoots.map { ShadowViewInfo(it) }
// Create an index of all the nodes indexed by their layoutInfo so we can quickly lookup
// the ShadowNode based on its LayoutInfo
val shadowNodesWithLayoutInfo = shadowTreeRoots
.flatMap { it.allNodes }
.map { it.layoutInfo to it }
.filter { it.first != null }
.groupBy { it.first }
val currentRoots = LinkedHashSet(shadowTreeRoots)
// Now, for each root, see if it can be attached to any other tree.
shadowTreeRoots
.forEach { rootToAttach ->
rootToAttach
// For the root we are trying to find, if it belongs somewhere else, get all
// nodes and see if any has a LayoutInfo parent information that matches the
// LayoutInfo in a separate tree.
.allNodes
.flatMap { candidate ->
shadowNodesWithLayoutInfo[candidate.layoutInfo?.parentInfo] ?: emptyList()
}
.filter {
// Ensure that the node we have found is in a different root
it.second.findRoot() != rootToAttach
}
.map { (_, candidateNode) -> candidateNode }
.firstOrNull()?.let { nodeToAttachTo ->
// We found it, re-attach to the candidate node
rootToAttach.setNewParent(nodeToAttachTo)
currentRoots.remove(rootToAttach)
}
}
val newTree = currentRoots.map {
it.toViewInfo()
}
return newTree
}