134 lines
5.3 KiB
Java
134 lines
5.3 KiB
Java
/*
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* Copyright (C) 2014 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package android.media.midi;
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import java.io.IOException;
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/**
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* Interface for sending and receiving data to and from a MIDI device.
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*/
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abstract public class MidiReceiver {
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private final int mMaxMessageSize;
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/**
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* Default MidiReceiver constructor. Maximum message size is set to
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* {@link java.lang.Integer#MAX_VALUE}
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*/
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public MidiReceiver() {
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mMaxMessageSize = Integer.MAX_VALUE;
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}
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/**
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* MidiReceiver constructor.
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* @param maxMessageSize the maximum size of a message this receiver can receive
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*/
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public MidiReceiver(int maxMessageSize) {
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mMaxMessageSize = maxMessageSize;
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}
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/**
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* Called whenever the receiver is passed new MIDI data.
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* Subclasses override this method to receive MIDI data.
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* May fail if count exceeds {@link #getMaxMessageSize}.
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*
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* NOTE: the msg array parameter is only valid within the context of this call.
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* The msg bytes should be copied by the receiver rather than retaining a reference
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* to this parameter.
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* Also, modifying the contents of the msg array parameter may result in other receivers
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* in the same application receiving incorrect values in their {link #onSend} method.
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*
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* @param msg a byte array containing the MIDI data
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* @param offset the offset of the first byte of the data in the array to be processed
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* @param count the number of bytes of MIDI data in the array to be processed
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* @param timestamp the timestamp of the message (based on {@link java.lang.System#nanoTime}
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* @throws IOException
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*/
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abstract public void onSend(byte[] msg, int offset, int count, long timestamp)
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throws IOException;
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/**
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* Instructs the receiver to discard all pending MIDI data.
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* @throws IOException
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*/
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public void flush() throws IOException {
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onFlush();
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}
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/**
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* Called when the receiver is instructed to discard all pending MIDI data.
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* Subclasses should override this method if they maintain a list or queue of MIDI data
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* to be processed in the future.
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* @throws IOException
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*/
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public void onFlush() throws IOException {
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}
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/**
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* Returns the maximum size of a message this receiver can receive.
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* @return maximum message size
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*/
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public final int getMaxMessageSize() {
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return mMaxMessageSize;
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}
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/**
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* Called to send MIDI data to the receiver without a timestamp.
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* Data will be processed by receiver in the order sent.
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* Data will get split into multiple calls to {@link #onSend} if count exceeds
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* {@link #getMaxMessageSize}. Blocks until all the data is sent or an exception occurs.
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* In the latter case, the amount of data sent prior to the exception is not provided to caller.
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* The communication should be considered corrupt. The sender should reestablish
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* communication, reset all controllers and send all notes off.
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*
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* @param msg a byte array containing the MIDI data
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* @param offset the offset of the first byte of the data in the array to be sent
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* @param count the number of bytes of MIDI data in the array to be sent
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* @throws IOException if the data could not be sent in entirety
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*/
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public void send(byte[] msg, int offset, int count) throws IOException {
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// TODO add public static final TIMESTAMP_NONE = 0L
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send(msg, offset, count, 0L);
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}
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/**
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* Called to send MIDI data to the receiver with a specified timestamp.
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* Data will be processed by receiver in order first by timestamp, then in the order sent.
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* Data will get split into multiple calls to {@link #onSend} if count exceeds
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* {@link #getMaxMessageSize}. Blocks until all the data is sent or an exception occurs.
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* In the latter case, the amount of data sent prior to the exception is not provided to caller.
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* The communication should be considered corrupt. The sender should reestablish
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* communication, reset all controllers and send all notes off.
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*
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* @param msg a byte array containing the MIDI data
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* @param offset the offset of the first byte of the data in the array to be sent
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* @param count the number of bytes of MIDI data in the array to be sent
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* @param timestamp the timestamp of the message, based on {@link java.lang.System#nanoTime}
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* @throws IOException if the data could not be sent in entirety
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*/
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public void send(byte[] msg, int offset, int count, long timestamp)
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throws IOException {
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int messageSize = getMaxMessageSize();
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while (count > 0) {
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int length = (count > messageSize ? messageSize : count);
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onSend(msg, offset, length, timestamp);
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offset += length;
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count -= length;
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}
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}
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}
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