flutteraudioplayer.dart

import 'dart:async';
import 'dart:io';
import 'dart:typed_data';

import 'package:audioplayer/audioplayer.dart';
import 'package:flutter/material.dart';
import 'package:http/http.dart';
import 'package:path_provider/path_provider.dart';

typedef void OnError(Exception exception);

var kUrl = "";

class FlutterAudioPlayer extends StatelessWidget {

  String url;

  FlutterAudioPlayer(this.url) {
    kUrl = url;
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
        appBar: AppBar(
          backgroundColor: Colors.blueAccent,
        ),
        body: new AudioApp());
  }
}


enum PlayerState { stopped, playing, paused }

class AudioApp extends StatefulWidget {
  @override
  _AudioAppState createState() => new _AudioAppState();
}

class _AudioAppState extends State<AudioApp> {
  Duration duration;
  Duration position;

  AudioPlayer audioPlayer;

  String localFilePath;

  PlayerState playerState = PlayerState.stopped;

  get isPlaying => playerState == PlayerState.playing;
  get isPaused => playerState == PlayerState.paused;

  get durationText =>
      duration != null ? duration.toString().split('.').first : '';
  get positionText =>
      position != null ? position.toString().split('.').first : '';

  bool isMuted = false;

  StreamSubscription _positionSubscription;
  StreamSubscription _audioPlayerStateSubscription;

  @override
  void initState() {
    super.initState();
    initAudioPlayer();
  }

  @override
  void dispose() {
    _positionSubscription.cancel();
    _audioPlayerStateSubscription.cancel();
    audioPlayer.stop();
    super.dispose();
  }

  void initAudioPlayer() {
    audioPlayer = new AudioPlayer();
    _positionSubscription = audioPlayer.onAudioPositionChanged
        .listen((p) => setState(() => position = p));
    _audioPlayerStateSubscription =
        audioPlayer.onPlayerStateChanged.listen((s) {
          if (s == AudioPlayerState.PLAYING) {
            setState(() => duration = audioPlayer.duration);
          } else if (s == AudioPlayerState.STOPPED) {
            onComplete();
            setState(() {
              position = duration;
            });
          }
        }, onError: (msg) {
          setState(() {
            playerState = PlayerState.stopped;
            duration = new Duration(seconds: 0);
            position = new Duration(seconds: 0);
          });
        });
  }

  Future play() async {
    await audioPlayer.play(kUrl);
    setState(() {
      playerState = PlayerState.playing;
    });
  }

  Future _playLocal() async {
    await audioPlayer.play(localFilePath, isLocal: true);
    setState(() => playerState = PlayerState.playing);
  }

  Future pause() async {
    await audioPlayer.pause();
    setState(() => playerState = PlayerState.paused);
  }

  Future stop() async {
    await audioPlayer.stop();
    setState(() {
      playerState = PlayerState.stopped;
      position = new Duration();
    });
  }

  Future mute(bool muted) async {
    await audioPlayer.mute(muted);
    setState(() {
      isMuted = muted;
    });
  }

  void onComplete() {
    setState(() => playerState = PlayerState.stopped);
  }

  Future<Uint8List> _loadFileBytes(String url, {OnError onError}) async {
    Uint8List bytes;
    try {
      bytes = await readBytes(url);
    } on ClientException {
      rethrow;
    }
    return bytes;
  }

  Future _loadFile() async {
    final bytes = await _loadFileBytes(kUrl,
        onError: (Exception exception) =>
            print('_loadFile => exception $exception'));

    final dir = await getApplicationDocumentsDirectory();
    final file = new File('${dir.path}/audio.mp3');

    await file.writeAsBytes(bytes);
    if (await file.exists())
      setState(() {
        localFilePath = file.path;
      });
  }

  @override
  Widget build(BuildContext context) {
    return new Center(
        child: new Material(
            elevation: 2.0,
            color: Colors.grey[200],
            child: new Column(
                children: [
                  Card(child: new Material(child: _buildPlayer())),
                  localFilePath != null
                      ? new Text(localFilePath)
                      : new Container(),
                ])));
  }

  Widget _buildPlayer() => new Container(
      padding: new EdgeInsets.all(16.0),
      child: new Column(mainAxisSize: MainAxisSize.min, children: [
        new Row(mainAxisSize: MainAxisSize.min, children: [
          new IconButton(
              onPressed: isPlaying ? null : () => play(),
              iconSize: 64.0,
              icon: new Icon(Icons.play_arrow),
              color: Colors.blueAccent),
          new IconButton(
              onPressed: isPlaying ? () => pause() : null,
              iconSize: 64.0,
              icon: new Icon(Icons.pause),
              color: Colors.blueAccent),
          new IconButton(
              onPressed: isPlaying || isPaused ? () => stop() : null,
              iconSize: 64.0,
              icon: new Icon(Icons.stop),
              color: Colors.blueAccent),
        ]),
        duration == null
            ? new Container()
            : new Slider(
            value: position?.inMilliseconds?.toDouble() ?? 0.0,
            onChanged: (double value) =>
                audioPlayer.seek((value / 1000).roundToDouble()),
            min: 0.0,
            max: duration.inMilliseconds.toDouble()),
        new Row(
          mainAxisAlignment: MainAxisAlignment.spaceEvenly,
          children: <Widget>[
            new IconButton(
                onPressed: () => mute(true),
                icon: new Icon(Icons.headset_off),
                color: Colors.blueAccent),
            new IconButton(
                onPressed: () => mute(false),
                icon: new Icon(Icons.headset),
                color: Colors.blueAccent),
          ],
        ),
        new Row(mainAxisSize: MainAxisSize.min, children: [
          new Padding(
              padding: new EdgeInsets.all(12.0),
              child: new Stack(children: [
                new CircularProgressIndicator(
                    value: 1.0,
                    valueColor: new AlwaysStoppedAnimation(Colors.grey[300])),
                new CircularProgressIndicator(
                  value: position != null && position.inMilliseconds > 0
                      ? (position?.inMilliseconds?.toDouble() ?? 0.0) /
                      (duration?.inMilliseconds?.toDouble() ?? 0.0)
                      : 0.0,
                  valueColor: new AlwaysStoppedAnimation(Colors.blueAccent),
                  backgroundColor: Colors.yellow,
                ),
              ])),
          new Text(
              position != null
                  ? "${positionText ?? ''} / ${durationText ?? ''}"
                  : duration != null ? durationText : '',
              style: new TextStyle(fontSize: 24.0))
        ])
      ]));
}