| /* |
| * Copyright 2019 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.lifecycle; |
| |
| import android.view.View; |
| import android.view.ViewParent; |
| |
| import androidx.annotation.NonNull; |
| import androidx.annotation.Nullable; |
| import androidx.lifecycle.runtime.R; |
| |
| /** |
| * Accessors for finding a view tree-local {@link LifecycleOwner} that reports the lifecycle for |
| * the given view. |
| */ |
| public class ViewTreeLifecycleOwner { |
| private ViewTreeLifecycleOwner() { |
| // No instances |
| } |
| |
| /** |
| * Set the {@link LifecycleOwner} responsible for managing the given {@link View}. |
| * Calls to {@link #get(View)} from this view or descendants will return {@code lifecycleOwner}. |
| * |
| * <p>This should only be called by constructs such as activities or fragments that manage |
| * a view tree and reflect their own lifecycle through a {@link LifecycleOwner}. Callers |
| * should only set a {@link LifecycleOwner} that will be <em>stable.</em> The associated |
| * lifecycle should report that it is destroyed if the view tree is removed and is not |
| * guaranteed to later become reattached to a window.</p> |
| * |
| * @param view Root view managed by lifecycleOwner |
| * @param lifecycleOwner LifecycleOwner representing the manager of the given view |
| */ |
| public static void set(@NonNull View view, @Nullable LifecycleOwner lifecycleOwner) { |
| view.setTag(R.id.view_tree_lifecycle_owner, lifecycleOwner); |
| } |
| |
| /** |
| * Retrieve the {@link LifecycleOwner} responsible for managing the given {@link View}. |
| * This may be used to scope work or heavyweight resources associated with the view |
| * that may span cycles of the view becoming detached and reattached from a window. |
| * |
| * @param view View to fetch a {@link LifecycleOwner} for |
| * @return The {@link LifecycleOwner} responsible for managing this view and/or some subset |
| * of its ancestors |
| */ |
| @Nullable |
| public static LifecycleOwner get(@NonNull View view) { |
| LifecycleOwner found = (LifecycleOwner) view.getTag(R.id.view_tree_lifecycle_owner); |
| if (found != null) return found; |
| ViewParent parent = view.getParent(); |
| while (found == null && parent instanceof View) { |
| final View parentView = (View) parent; |
| found = (LifecycleOwner) parentView.getTag(R.id.view_tree_lifecycle_owner); |
| parent = parentView.getParent(); |
| } |
| return found; |
| } |
| } |
