1 /* 2 * Copyright (C) 2016 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 package com.google.android.exoplayer2.source; 17 18 import com.google.android.exoplayer2.C; 19 20 // TODO: Clarify the requirements for implementing this interface [Internal ref: b/36250203]. 21 /** 22 * A loader that can proceed in approximate synchronization with other loaders. 23 */ 24 public interface SequenceableLoader { 25 26 /** 27 * A callback to be notified of {@link SequenceableLoader} events. 28 */ 29 interface Callback<T extends SequenceableLoader> { 30 31 /** 32 * Called by the loader to indicate that it wishes for its {@link #continueLoading(long)} method 33 * to be called when it can continue to load data. Called on the playback thread. 34 */ onContinueLoadingRequested(T source)35 void onContinueLoadingRequested(T source); 36 37 } 38 39 /** 40 * Returns an estimate of the position up to which data is buffered. 41 * 42 * @return An estimate of the absolute position in microseconds up to which data is buffered, or 43 * {@link C#TIME_END_OF_SOURCE} if the data is fully buffered. 44 */ getBufferedPositionUs()45 long getBufferedPositionUs(); 46 47 /** 48 * Returns the next load time, or {@link C#TIME_END_OF_SOURCE} if loading has finished. 49 */ getNextLoadPositionUs()50 long getNextLoadPositionUs(); 51 52 /** 53 * Attempts to continue loading. 54 * 55 * @param positionUs The current playback position in microseconds. If playback of the period to 56 * which this loader belongs has not yet started, the value will be the starting position 57 * in the period minus the duration of any media in previous periods still to be played. 58 * @return True if progress was made, meaning that {@link #getNextLoadPositionUs()} will return 59 * a different value than prior to the call. False otherwise. 60 */ continueLoading(long positionUs)61 boolean continueLoading(long positionUs); 62 63 /** Returns whether the loader is currently loading. */ isLoading()64 boolean isLoading(); 65 66 /** 67 * Re-evaluates the buffer given the playback position. 68 * 69 * <p>Re-evaluation may discard buffered media so that it can be re-buffered in a different 70 * quality. 71 * 72 * @param positionUs The current playback position in microseconds. If playback of this period has 73 * not yet started, the value will be the starting position in this period minus the duration 74 * of any media in previous periods still to be played. 75 */ reevaluateBuffer(long positionUs)76 void reevaluateBuffer(long positionUs); 77 } 78