1 /* 2 * Copyright 2019 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 @file:JvmName("ViewTreeLifecycleOwner") 17 18 package androidx.lifecycle 19 20 import android.view.View 21 import androidx.core.viewtree.getParentOrViewTreeDisjointParent 22 import androidx.lifecycle.runtime.R 23 24 /** 25 * Set the [LifecycleOwner] responsible for managing the given [View]. Calls to [get] from this view 26 * or descendants will return `lifecycleOwner`. 27 * 28 * This should only be called by constructs such as activities or fragments that manage a view tree 29 * and reflect their own lifecycle through a [LifecycleOwner]. Callers should only set a 30 * [LifecycleOwner] that will be *stable.* The associated lifecycle should report that it is 31 * destroyed if the view tree is removed and is not guaranteed to later become reattached to a 32 * window. 33 * 34 * @param lifecycleOwner LifecycleOwner representing the manager of the given view 35 */ 36 @JvmName("set") setViewTreeLifecycleOwnernull37public fun View.setViewTreeLifecycleOwner(lifecycleOwner: LifecycleOwner?) { 38 setTag(R.id.view_tree_lifecycle_owner, lifecycleOwner) 39 } 40 41 /** 42 * Retrieve the [LifecycleOwner] responsible for managing the given [View]. This may be used to 43 * scope work or heavyweight resources associated with the view that may span cycles of the view 44 * becoming detached and reattached from a window. 45 * 46 * @return The [LifecycleOwner] responsible for managing this view and/or some subset of its 47 * ancestors 48 */ 49 @JvmName("get") findViewTreeLifecycleOwnernull50public fun View.findViewTreeLifecycleOwner(): LifecycleOwner? { 51 var currentView: View? = this 52 while (currentView != null) { 53 val lifecycleOwner = currentView.getTag(R.id.view_tree_lifecycle_owner) as? LifecycleOwner 54 if (lifecycleOwner != null) { 55 return lifecycleOwner 56 } 57 currentView = currentView.getParentOrViewTreeDisjointParent() as? View 58 } 59 return null 60 } 61