1/* 2 * Copyright 2018 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.paging; 18 19import androidx.annotation.NonNull; 20import androidx.annotation.RestrictTo; 21import androidx.annotation.WorkerThread; 22 23import java.util.Collections; 24import java.util.List; 25 26// NOTE: Room 1.0 depends on this class, so it should not be removed until 27// we can require a version of Room that uses PositionalDataSource directly 28/** 29 * @param <T> Type loaded by the TiledDataSource. 30 * 31 * @deprecated Use {@link PositionalDataSource} 32 * @hide 33 */ 34@SuppressWarnings("DeprecatedIsStillUsed") 35@Deprecated 36@RestrictTo(RestrictTo.Scope.LIBRARY_GROUP) 37public abstract class TiledDataSource<T> extends PositionalDataSource<T> { 38 39 @WorkerThread 40 public abstract int countItems(); 41 42 @Override 43 boolean isContiguous() { 44 return false; 45 } 46 47 @WorkerThread 48 public abstract List<T> loadRange(int startPosition, int count); 49 50 @Override 51 public void loadInitial(@NonNull LoadInitialParams params, 52 @NonNull LoadInitialCallback<T> callback) { 53 int totalCount = countItems(); 54 if (totalCount == 0) { 55 callback.onResult(Collections.<T>emptyList(), 0, 0); 56 return; 57 } 58 59 // bound the size requested, based on known count 60 final int firstLoadPosition = computeInitialLoadPosition(params, totalCount); 61 final int firstLoadSize = computeInitialLoadSize(params, firstLoadPosition, totalCount); 62 63 // convert from legacy behavior 64 List<T> list = loadRange(firstLoadPosition, firstLoadSize); 65 if (list != null && list.size() == firstLoadSize) { 66 callback.onResult(list, firstLoadPosition, totalCount); 67 } else { 68 // null list, or size doesn't match request 69 // The size check is a WAR for Room 1.0, subsequent versions do the check in Room 70 invalidate(); 71 } 72 } 73 74 @Override 75 public void loadRange(@NonNull LoadRangeParams params, 76 @NonNull LoadRangeCallback<T> callback) { 77 List<T> list = loadRange(params.startPosition, params.loadSize); 78 if (list != null) { 79 callback.onResult(list); 80 } else { 81 invalidate(); 82 } 83 } 84} 85