1/* 2 * Copyright (C) 2017 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 17package androidx.wear.widget.drawer; 18 19import android.view.View; 20import android.widget.AbsListView; 21import android.widget.ScrollView; 22 23import androidx.annotation.Nullable; 24import androidx.annotation.RestrictTo; 25import androidx.annotation.RestrictTo.Scope; 26import androidx.core.widget.NestedScrollView; 27import androidx.recyclerview.widget.RecyclerView; 28 29import java.util.Map; 30import java.util.WeakHashMap; 31 32/** 33 * Creates a {@link FlingWatcher} based on the type of {@link View}. 34 * 35 * @hide 36 */ 37@RestrictTo(Scope.LIBRARY) 38class FlingWatcherFactory { 39 40 /** 41 * Listener that is notified when a fling completes and the view has settled. Polling may be 42 * used to determine when the fling has completed, so there may be up to a 100ms delay. 43 */ 44 interface FlingListener { 45 void onFlingComplete(View view); 46 } 47 48 /** 49 * Watches a given {@code view} to detect the end of a fling. Will notify a {@link 50 * FlingListener} when the end is found. 51 */ 52 interface FlingWatcher { 53 void watch(); 54 } 55 56 private final FlingListener mListener; 57 private final Map<View, FlingWatcher> mWatchers = new WeakHashMap<>(); 58 59 FlingWatcherFactory(FlingListener listener) { 60 if (listener == null) { 61 throw new IllegalArgumentException("FlingListener was null"); 62 } 63 64 mListener = listener; 65 } 66 67 /** 68 * Returns a {@link FlingWatcher} for the particular type of {@link View}. 69 */ 70 @Nullable 71 FlingWatcher getFor(View view) { 72 FlingWatcher watcher = mWatchers.get(view); 73 if (watcher == null) { 74 watcher = createFor(view); 75 if (watcher != null) { 76 mWatchers.put(view, watcher); 77 } 78 } 79 80 return watcher; 81 } 82 83 /** 84 * Creates a {@link FlingWatcher} for the particular type of {@link View}. 85 */ 86 @Nullable 87 private FlingWatcher createFor(View view) { 88 if (view == null) { 89 throw new IllegalArgumentException("View was null"); 90 } 91 92 if (view instanceof RecyclerView) { 93 return new RecyclerViewFlingWatcher(mListener, (RecyclerView) view); 94 } else if (view instanceof AbsListView) { 95 return new AbsListViewFlingWatcher(mListener, (AbsListView) view); 96 } else if (view instanceof ScrollView) { 97 return new ScrollViewFlingWatcher(mListener, (ScrollView) view); 98 } else if (view instanceof NestedScrollView) { 99 return new NestedScrollViewFlingWatcher(mListener, (NestedScrollView) view); 100 } else { 101 return null; 102 } 103 } 104} 105