1 /* 2 * Copyright 2020 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("ViewTreeViewModelStoreOwner") 17 18 package androidx.lifecycle 19 20 import android.view.View 21 import androidx.core.viewtree.getParentOrViewTreeDisjointParent 22 import androidx.lifecycle.viewmodel.R 23 24 /** 25 * Set the [ViewModelStoreOwner] associated with the given [View]. Calls to [get] from this view or 26 * descendants will return `viewModelStoreOwner`. 27 * 28 * This should only be called by constructs such as activities or fragments that manage a view tree 29 * and retain state through a [ViewModelStoreOwner]. Callers should only set a [ViewModelStoreOwner] 30 * that will be *stable.* The associated [ViewModelStore] should be cleared if the view tree is 31 * removed and is not guaranteed to later become reattached to a window. 32 * 33 * @param viewModelStoreOwner ViewModelStoreOwner associated with the given view 34 */ 35 @JvmName("set") setViewTreeViewModelStoreOwnernull36public fun View.setViewTreeViewModelStoreOwner(viewModelStoreOwner: ViewModelStoreOwner?) { 37 setTag(R.id.view_tree_view_model_store_owner, viewModelStoreOwner) 38 } 39 40 /** 41 * Retrieve the [ViewModelStoreOwner] associated with the given [View]. This may be used to retain 42 * state associated with this view across configuration changes. 43 * 44 * @return The [ViewModelStoreOwner] associated with this view and/or some subset of its ancestors 45 */ 46 @JvmName("get") findViewTreeViewModelStoreOwnernull47public fun View.findViewTreeViewModelStoreOwner(): ViewModelStoreOwner? { 48 var currentView: View? = this 49 while (currentView != null) { 50 val storeOwner = 51 currentView.getTag(R.id.view_tree_view_model_store_owner) as? ViewModelStoreOwner 52 if (storeOwner != null) { 53 return storeOwner 54 } 55 currentView = currentView.getParentOrViewTreeDisjointParent() as? View 56 } 57 return null 58 } 59