tomkaminski / flutter_midi_pro

flutter_midi_pro

The flutter_midi_pro plugin provides functions for loading SoundFont (.sf2) files, as well as playing and stopping MIDI notes.

Installation

To use this plugin, add flutter_midi_pro as a dependency in your pubspec.yaml file. For example:

dependencies:
  flutter_midi_pro: ^2.0.1

Usage

Import flutter_midi_pro.dart and use the MidiPro class to access the plugin's functions.

import 'package:flutter_midi_pro/flutter_midi_pro.dart';

Create a MidiPro Variable

final midiPro = MidiPro();

Load SoundFont File

Use the loadSoundfont function to load a SoundFont file. You can either load the SoundFont file from an asset or from a file path. You can also specify the instrument index to load a specific instrument from the SoundFont file.

await midiPro.loadSoundfont(sf2Path: 'YOUR SOUNDFONT FILE PATH', instrumentIndex: 0);

Play MIDI Note

Use the playMidiNote function to play a MIDI note with a given MIDI value and velocity.

midiPro.playMidiNote(midi: midiIndex, velocity: velocity)

Stop MIDI Note

Use the stopMidiNote function to stop a MIDI note with a given MIDI number.

midiPro.stopMidiNote(midi: midiIndex);

Load Instrument

Use the loadInstrument function to load a specific instrument from the SoundFont file.

await midiPro.loadInstrument(instrumentIndex: 0);

Example

Here's an example of how you could use the flutter_midi_pro plugin to play a piano using a SoundFont file and using the flutter_piano_pro:

import 'package:flutter/material.dart';
import 'package:flutter_midi_pro/flutter_midi_pro.dart';
import 'package:flutter_piano_pro/flutter_piano_pro.dart';
import 'package:flutter_piano_pro/note_model.dart';

class MainPage extends StatefulWidget {
  const MainPage({super.key});

  @override
  State<MainPage> createState() => _MainPageState();
}

class _MainPageState extends State<MainPage> {
  final _midi = MidiPro();
  final instrumentIndex = ValueNotifier<int>(0);
  final volume = ValueNotifier<int>(127);
  Future loadSoundfont() async {
    await _midi.loadSoundfont(
        sf2Path: 'assets/TimGM6mb.sf2', instrumentIndex: instrumentIndex.value);
  }

  Future loadInstrument() async {
    await _midi.loadInstrument(instrumentIndex: instrumentIndex.value);
  }

  Map<int, NoteModel> pointerAndNote = {};

  void play(int midi, {int velocity = 127}) {
    _midi.playMidiNote(midi: midi, velocity: velocity).then((value) => debugPrint('play: $midi'));
  }

  void stop({required int midi}) {
    _midi.stopMidiNote(midi: midi).then((value) => debugPrint('stop: $midi'));
  }

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

  @override
  void dispose() {
    super.dispose();
    _midi.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Flutter Midi Pro Example'),
      ),
      body: Center(
          child: Column(
        crossAxisAlignment: CrossAxisAlignment.center,
        mainAxisSize: MainAxisSize.min,
        mainAxisAlignment: MainAxisAlignment.center,
        children: <Widget>[
          ValueListenableBuilder(
              valueListenable: instrumentIndex,
              builder: (context, channelValue, child) {
                return DropdownButton<int>(
                    value: channelValue,
                    items: [
                      for (int i = 0; i < 128; i++)
                        DropdownMenuItem<int>(
                          value: i,
                          child: Text('Instrument $i'),
                        )
                    ],
                    onChanged: (int? value) {
                      if (value != null) {
                        instrumentIndex.value = value;
                      }
                    });
              }),
          const SizedBox(
            height: 10,
          ),
          ElevatedButton(
              onPressed: () {
                loadSoundfont();
              },
              child: const Text(
                'Load Soundfont file\nMust be called before other methods',
                textAlign: TextAlign.center,
              )),
          const SizedBox(
            height: 10,
          ),
          ValueListenableBuilder(
              valueListenable: instrumentIndex,
              builder: (context, instrumentIndexValue, child) {
                return ElevatedButton(
                    onPressed: () {
                      loadInstrument();
                    },
                    child: Text('Load Instrument $instrumentIndexValue'));
              }),
          Padding(
              padding: const EdgeInsets.all(18),
              child: ValueListenableBuilder(
                  valueListenable: volume,
                  child: const Text('Volume: '),
                  builder: (context, value, child) {
                    return Row(
                      children: [
                        child!,
                        Expanded(
                            child: Slider(
                          value: value.toDouble(),
                          min: 0,
                          max: 127,
                          onChanged: (value) {
                            volume.value = value.toInt();
                          },
                        )),
                        const SizedBox(
                          width: 10,
                        ),
                        Text('${volume.value}'),
                      ],
                    );
                  })),
          PianoPro(
            noteCount: 15,
            onTapDown: (NoteModel? note, int tapId) {
              if (note == null) return;
              play(note.midiNoteNumber, velocity: volume.value);
              setState(() => pointerAndNote[tapId] = note);
              debugPrint(
                  'DOWN: note= ${note.name + note.octave.toString() + (note.isFlat ? "♭" : '')}, tapId= $tapId');
            },
            onTapUpdate: (NoteModel? note, int tapId) {
              if (note == null) return;
              if (pointerAndNote[tapId] == note) return;
              stop(midi: pointerAndNote[tapId]!.midiNoteNumber);
              play(note.midiNoteNumber, velocity: volume.value);
              setState(() => pointerAndNote[tapId] = note);
              debugPrint(
                  'UPDATE: note= ${note.name + note.octave.toString() + (note.isFlat ? "♭" : '')}, tapId= $tapId');
            },
            onTapUp: (int tapId) {
              stop(midi: pointerAndNote[tapId]!.midiNoteNumber);
              setState(() => pointerAndNote.remove(tapId));
              debugPrint('UP: tapId= $tapId');
            },
          )
        ],
      )),
    );
  }
}

Contributions

Contributions are welcome! Please feel free to submit a PR or open an issue.

TODOS

• Add support for Web, Windows, and Linux.
• Add support for channel feature (MIDI Channels).
• Add controller support
• Add support for MIDI files.

Contact

If you have any questions or suggestions, feel free to contact the package maintainer, Melih Hakan Pektas, via email or through GitHub.

Thank you for contributing to flutter_piano_pro!

License

This project is licensed under the MIT License. See the LICENSE file for details.