Flutter MIDI控制器插件midi_controller的使用

Flutter MIDI控制器插件midi_controller的使用

midi_controller 是一个用于 Dart 的 MIDI 控制器包。它可以发送和接收 MIDI 消息，并连接到网络 MIDI 会话。

完整示例Demo

以下是一个完整的示例代码，展示了如何使用 midi_controller 插件来创建一个简单的 MIDI 设备列表视图。

import 'dart:async';

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:midi_controller/midi_command.dart';

import 'controller.dart';

void main() => runApp(const MyApp());

class MyApp extends StatefulWidget {
  const MyApp({Key? key}) : super(key: key);

  [@override](/user/override)
  MyAppState createState() => MyAppState();
}

class MyAppState extends State<MyApp> {
  StreamSubscription<String>? _setupSubscription;
  final MidiCommand _midiCommand = MidiCommand();

  bool _virtualDeviceActivated = false;
  bool _iOSNetworkSessionEnabled = false;

  [@override](/user/override)
  void initState() {
    super.initState();

    _setupSubscription = _midiCommand.onMidiSetupChanged?.listen((data) async {
      if (kDebugMode) {
        print("setup changed $data");
      }
      setState(() {});
    });

    _updateNetworkSessionState();
  }

  [@override](/user/override)
  void dispose() {
    _setupSubscription?.cancel();
    super.dispose();
  }

  _updateNetworkSessionState() async {
    var nse = await _midiCommand.isNetworkSessionEnabled;
    if (nse != null) {
      setState(() {
        _iOSNetworkSessionEnabled = nse;
      });
    }
  }

  IconData _deviceIconForType(String type) {
    switch (type) {
      case "native":
        return Icons.devices;
      case "network":
        return Icons.language;
      case "BLE":
        return Icons.bluetooth;
      default:
        return Icons.device_unknown;
    }
  }

  [@override](/user/override)
  Widget build(BuildContext context) {
    SystemChrome.setPreferredOrientations([
      DeviceOrientation.landscapeLeft,
      DeviceOrientation.landscapeRight,
    ]);
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
            title: const Text('FlutterMidiCommand Example'),
            actions: <Widget>[
              Switch(
                  value: _iOSNetworkSessionEnabled,
                  onChanged: (newValue) {
                    _midiCommand.setNetworkSessionEnabled(newValue);
                    setState(() {
                      _iOSNetworkSessionEnabled = newValue;
                    });
                  }),
              Switch(
                  value: _virtualDeviceActivated,
                  onChanged: (newValue) {
                    setState(() {
                      _virtualDeviceActivated = newValue;
                    });
                    if (newValue) {
                      _midiCommand.addVirtualDevice(
                          name: "Flutter MIDI Command");
                    } else {
                      _midiCommand.removeVirtualDevice(
                          name: "Flutter MIDI Command");
                    }
                  })
            ]),
        bottomNavigationBar: Container(
          padding: const EdgeInsets.all(24.0),
          child: const Text(
            "Tap to connect/disconnect, long press to control.",
            textAlign: TextAlign.center,
          ),
        ),
        body: Center(
          child: FutureBuilder(
            future: _midiCommand.devices,
            builder: (BuildContext context, AsyncSnapshot snapshot) {
              if (snapshot.hasData && snapshot.data != null) {
                var devices = snapshot.data as List<MidiDevice>;
                return ListView.builder(
                  itemCount: devices.length,
                  itemBuilder: (context, index) {
                    MidiDevice device = devices[index];

                    return ListTile(
                      title: Text(
                        device.name,
                        style: Theme.of(context).textTheme.headlineSmall,
                      ),
                      subtitle: Text(
                          "ins:${device.inputPorts.length} outs:${device.outputPorts.length}, ${device.id}, ${device.type}"),
                      leading: Icon(device.connected
                          ? Icons.radio_button_on
                          : Icons.radio_button_off),
                      trailing: Icon(_deviceIconForType(device.type)),
                      onLongPress: () {
                        Navigator.of(context)
                            .push(MaterialPageRoute<void>(
                          builder: (_) => ControllerPage(device),
                        ))
                            .then((value) {
                          setState(() {});
                        });
                      },
                      onTap: () {
                        if (device.connected) {
                          if (kDebugMode) {
                            print("disconnect");
                          }
                          _midiCommand.disconnectDevice(device);
                        } else {
                          if (kDebugMode) {
                            print("connect");
                          }
                          _midiCommand.connectToDevice(device).then((_) {
                            if (kDebugMode) {
                              print("device connected async");
                            }
                          }).catchError((err) {
                            ScaffoldMessenger.of(context).showSnackBar(SnackBar(
                                content: Text(
                                    "Error: ${(err as PlatformException?)?.message}")));
                          });
                        }
                      },
                    );
                  },
                );
              } else {
                return const CircularProgressIndicator();
              }
            },
          ),
        ),
      ),
    );
  }
}