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 android.support.wear.widget.drawer; 18 19import android.support.annotation.RestrictTo; 20import android.support.annotation.RestrictTo.Scope; 21import android.support.v7.widget.RecyclerView; 22import android.support.v7.widget.RecyclerView.OnScrollListener; 23import android.support.wear.widget.drawer.FlingWatcherFactory.FlingListener; 24import android.support.wear.widget.drawer.FlingWatcherFactory.FlingWatcher; 25 26import java.lang.ref.WeakReference; 27 28/** 29 * {@link FlingWatcher} implementation for {@link RecyclerView RecyclerViews}. Detects the end of 30 * a Fling by waiting until the scroll state becomes idle. 31 * 32 * @hide 33 */ 34@RestrictTo(Scope.LIBRARY_GROUP) 35class RecyclerViewFlingWatcher extends OnScrollListener implements FlingWatcher { 36 37 private final FlingListener mListener; 38 private final WeakReference<RecyclerView> mRecyclerView; 39 40 RecyclerViewFlingWatcher(FlingListener listener, RecyclerView view) { 41 mListener = listener; 42 mRecyclerView = new WeakReference<>(view); 43 } 44 45 @Override 46 public void watch() { 47 RecyclerView recyclerView = mRecyclerView.get(); 48 if (recyclerView != null) { 49 recyclerView.addOnScrollListener(this); 50 } 51 } 52 53 @Override 54 public void onScrollStateChanged(RecyclerView recyclerView, int newState) { 55 if (newState == RecyclerView.SCROLL_STATE_IDLE) { 56 mListener.onFlingComplete(recyclerView); 57 recyclerView.removeOnScrollListener(this); 58 } 59 } 60} 61