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      1 /*
      2  * Copyright 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 
     17 
     18 package android.media;
     19 
     20 import java.io.Closeable;
     21 import java.io.IOException;
     22 
     23 /**
     24  * @hide
     25  * For supplying media data to the framework. Implement this if your app has
     26  * special requirements for the way media data is obtained.
     27  *
     28  * <p class="note">Methods of this interface may be called on multiple different
     29  * threads. There will be a thread synchronization point between each call to ensure that
     30  * modifications to the state of your Media2DataSource are visible to future calls. This means
     31  * you don't need to do your own synchronization unless you're modifying the
     32  * Media2DataSource from another thread while it's being used by the framework.</p>
     33  *
     34  */
     35 public abstract class Media2DataSource implements Closeable {
     36     /**
     37      * Called to request data from the given position.
     38      *
     39      * Implementations should should write up to {@code size} bytes into
     40      * {@code buffer}, and return the number of bytes written.
     41      *
     42      * Return {@code 0} if size is zero (thus no bytes are read).
     43      *
     44      * Return {@code -1} to indicate that end of stream is reached.
     45      *
     46      * @param position the position in the data source to read from.
     47      * @param buffer the buffer to read the data into.
     48      * @param offset the offset within buffer to read the data into.
     49      * @param size the number of bytes to read.
     50      * @throws IOException on fatal errors.
     51      * @return the number of bytes read, or -1 if there was an error.
     52      */
     53     public abstract int readAt(long position, byte[] buffer, int offset, int size)
     54             throws IOException;
     55 
     56     /**
     57      * Called to get the size of the data source.
     58      *
     59      * @throws IOException on fatal errors
     60      * @return the size of data source in bytes, or -1 if the size is unknown.
     61      */
     62     public abstract long getSize() throws IOException;
     63 }
     64