On-device Custom Voice Commands for Flutter Apps

<key>NSMicrophoneUsageDescription</key>
<string>[Permission explanation]</string>

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.RECORD_AUDIO" />

dependencies:
  flutter_voice_processor: ^{LATEST_VERSION}
  rhino_flutter: ^{LATEST_VERSION}

flutter:
  assets:
    - assets/${CONTEXT_FILE_ANDROID} # e.g. assets/coffee_maker_android.rhn
    - assets/${CONTEXT_FILE_IOS} # e.g. assets/coffee_maker_ios.rhn

flutter:
  assets:
    - assets/${CONTEXT_FILE_ANDROID}
    - assets/${CONTEXT_FILE_IOS}
    - assets/${MODEL_FILE} # e.g. assets/rhino_params_de.pv

import 'package:rhino_flutter/rhino.dart';

// ...
  void _inferenceCallback(RhinoInference inference) {
    if (inference.isUnderstood!) {
      // take action based on inferred intent and slot values
      String intent = inference.intent!;
      Map<String, String> slots = inference.slots!;
    } else {
      // handle unsupported commands
      print("Inference not understood");
    }
  }

// import 'dart:io';
import 'package:rhino_flutter/rhino_manager.dart';

// ...
  // var platform = (Platform.isAndroid) ? "android" : "ios";
  var contextPath =
      "assets/{CONTEXT_FILE}"; // e.g. "assets/coffee_maker_$platform.rhn";
  _rhinoManager = await RhinoManager.create(
    "{ACCESS_KEY}",
    contextPath,
    _inferenceCallback,
    // modelPath: "assets/{MODEL_FILE}", // (if non-English context)
  );

await _rhinoManager?.process();

await _rhinoManager?.delete();

import 'dart:io';

import 'package:flutter/material.dart';
import 'package:rhino_flutter/rhino.dart';
import 'package:rhino_flutter/rhino_manager.dart';
import 'package:rhino_flutter/rhino_error.dart';

enum AppState { initial, loading, ready, listening }

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

  @override
  State<RhinoWidget> createState() => _RhinoWidgetState();
}

class _RhinoWidgetState extends State<RhinoWidget> {
  RhinoManager? _rhinoManager;
  AppState _appState = AppState.initial;

  // Handle detected inferences
  void _inferenceCallback(RhinoInference inference) {
    setState(() => _appState = AppState.ready);
    if (inference.isUnderstood!) {
      String intent = inference.intent!;
      Map<String, String> slots = inference.slots!;
      // take action based on inferred intent and slot values
      print("Inference intent: $intent");
      print("Inference slots: $slots");
    } else {
      // handle unsupported commands
      print("Inference not understood");
    }
  }

  // 1. Initialize Rhino
  Future<void> _init() async {
    setState(() => _appState = AppState.loading);

    if (_rhinoManager == null) {
      try {
        var platform = (Platform.isAndroid) ? "android" : "ios";
        var contextPath =
            "assets/{CONTEXT_FILE}"; // e.g. "assets/coffee_maker_$platform.rhn";
        _rhinoManager = await RhinoManager.create(
          "{ACCESS_KEY}",
          contextPath,
          _inferenceCallback,
          // modelPath: "{MODEL_FILE}", // (if non-English context)
        );

        setState(() => _appState = AppState.ready);
      } on RhinoException catch (err) {
        print('Rhino initialization failed: ${err.message}');
        setState(() => _appState = AppState.initial);
      }
    }
  }

  // 2. Start listening for contexts
  Future<void> _start() async {
    if (_rhinoManager == null) return;
    setState(() => _appState = AppState.loading);

    try {
      await _rhinoManager?.process();
      setState(() => _appState = AppState.listening);
    } on RhinoException catch (err) {
      print('Error starting voice processor: ${err.message}');
      setState(() => _appState = AppState.ready);
    }
  }

  // 3. Clean up resources
  Future<void> _delete() async {
    setState(() => _appState = AppState.loading);

    await _rhinoManager?.delete();
    _rhinoManager = null;

    setState(() => _appState = AppState.initial);
  }

  @override
  void dispose() {
    _rhinoManager?.delete();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        ElevatedButton(
          onPressed: _appState == AppState.initial ? _init : null,
          child: const Text('Init'),
        ),
        ElevatedButton(
          onPressed: _appState == AppState.ready ? _start : null,
          child: const Text('Start'),
        ),
        ElevatedButton(
          onPressed: _appState == AppState.ready ? _delete : null,
          child: const Text('Delete'),
        ),
      ],
    );
  }
}