Flutter Metronome 应用程序会随着值的变化而滞后并更新值

Question

作为 flutter 中的第一个应用程序，我想构建一个节拍器应用程序。UI 已经构建完成，但实际节拍器功能我仍然遇到以下问题：

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• 有时，节拍器会稍微滞后一点，只是足够，所以你会注意到它。flutter中有没有办法实现节拍器100%的精度？

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• 演奏时不改变细分（您必须停止并启动节拍器）。如果值“节奏”和“细分”发生变化，如何自动应用于节拍器订阅？我知道 Flutter 提供了 Listenable、Stream、InheritedWidget 等工具，但我还没有找到在现有代码中实现这些工具的方法。

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用户界面截图：

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这是代码（它不完全是我写的 -> 学分）：

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import \'dart:io\' show File;\nimport \'dart:async\';\nimport \'package:flutter/cupertino.dart\';\nimport \'package:quiver/async.dart\';\nimport \'package:audioplayers/audioplayers.dart\' show AudioPlayer;\nimport \'package:flutter/services.dart\' show ByteData, rootBundle;\nimport \'package:path_provider/path_provider.dart\' show getTemporaryDirectory;\n\n//credits: "Andi Qu", /sf/ask/3573388171/\n\nValueNotifier<int> tempo = ValueNotifier(100);\nint subdivision = 1;\nbool isPlaying = false;\n\nint soundIndex = 1;\nFile _soundFile;\n\nStreamSubscription<DateTime> _subscription;\n\nFuture<ByteData> _loadSound() async {\n  return await rootBundle.load(\'assets/sounds/sound_$soundIndex.wav\');\n}\n\nvoid _writeSound() async {\n  _soundFile = File(\n      \'${(await getTemporaryDirectory()).path}/sounds/sound_$soundIndex.wav\');\n  await _soundFile.writeAsBytes((await _loadSound()).buffer.asUint8List());\n  print("_writeSound executed");\n}\n\nvoid _playLocal() async {\n  final AudioPlayer _audioPlayer = AudioPlayer();\n  AudioPlayer.logEnabled = false;\n  await _audioPlayer.play(_soundFile.path, isLocal: true);\n}\n\n/// The actual method that plays the metronome\n\nvoid playpause() {\n  print("playpause triggered");\n  if (_soundFile == null) {\n    print("_soundFile = null ---> Soundfile written");\n    _writeSound();\n  }\n\n  if (isPlaying) {\n    _subscription.cancel();\n    isPlaying = false;\n    print("metronome stopped");\n  } else {\n    _subscription = Metronome.periodic(new Duration(\n            milliseconds: (60000 / (tempo.value * subdivision)).floor()))\n        .listen((d) => _playLocal());\n    isPlaying = true;\n    print("metronome started");\n  }\n}\n\nvoid increasetempo(int tempochange) {\n  tempo.value = tempo.value + tempochange;\n\n  if (isPlaying) {\n    _subscription.cancel();\n    print("_subscription canceled");\n    _subscription = Metronome.periodic(new Duration(\n            milliseconds: (60000 / (tempo.value * subdivision)).floor()))\n        .listen((d) => _playLocal());\n  }\n  print("tempo changed to ${tempo.value}");\n}\n\nvoid decreasetempo(int tempochange) {\n  tempo.value = tempo.value - tempochange;\n\n  if (isPlaying) {\n    _subscription.cancel();\n    print("_subscription canceled");\n    _subscription = Metronome.periodic(new Duration(\n            milliseconds: (60000 / (tempo.value * subdivision)).floor()))\n        .listen((d) => _playLocal());\n  }\n  print("tempo changed to ${tempo.value}");\n}\n

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Answer 1

尝试使用一个名为flutter_sequencer 的库，它帮助我创建了没有滞后的 Metronome，而任何其他解决方案和库都不起作用。

• https://github.com/mikeperri/flutter_sequencer
• https://pub.dev/packages/flutter_sequencer