Flutter Text To Speech: Speak several strings subsequently with different SpeechRates - dart

Question

I have a problem with the Flutter Text To Speech package.
When clicking on a FloatingActionButton I would like to speak/play several Strings (with different Speechrates) subsequently. However, when doing so, I can only hear the last string that I have passed onto the function and not the first one.
As you can see in the code below, I have tried to make use of the asynchronus programming (async / await).
import 'package:flutter/material.dart';
import 'dart:async';
import 'package:flutter_tts/flutter_tts.dart';
class SpeakerClass extends StatefulWidget{
#override
State<StatefulWidget> createState() {
// TODO: implement createState
return _SpeakerClassState();
}
}
class _SpeakerClassState extends State<SpeakerClass>{
String text1 = 'eins';
String text2 = 'zwei';
String text3 = 'drei';
String text4 = 'vier';
String currentTtsString;
double ttsSpeechRate1 = 0.5;
double ttsSpeechRate2 = 1.0;
double currentSpeechRate;
Future playTtsString1() async {
currentTtsString = text1;
currentSpeechRate = ttsSpeechRate1;
await runTextToSpeech(currentTtsString, currentSpeechRate);
return null;
}
Future playTtsString2() async {
currentTtsString = text2;
currentSpeechRate = ttsSpeechRate2;
await runTextToSpeech(currentTtsString, currentSpeechRate);
return null;
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: FloatingActionButton (
backgroundColor: Colors.blue,
child: Icon(Icons.volume_up, color: Colors.white),
onPressed: () async {
await playTtsString1();
await playTtsString2();
},
)
);
}
}
Future<void> runTextToSpeech(String currentTtsString, double currentSpeechRate) async {
FlutterTts flutterTts;
flutterTts = new FlutterTts();
await flutterTts.setLanguage("en-GB");
await flutterTts.setVolume(1.0);
await flutterTts.setPitch(1.0);
await flutterTts.isLanguageAvailable("en-GB");
await flutterTts.setSpeechRate(currentSpeechRate);
await flutterTts.speak(currentTtsString);
}
When pressing the FloatingActionButton I expect the program to first carry out the function playTtsString1 ("eins" with a speed of 0.5) and afterwards the function playTtsString2 ("zwei" with a speed of 1).
However, somehow I can only hear the program saying "zwei". I guess the program is not waiting for the first function "playTtsString1" to be finished and already carries out the second function "playTtsString2". I would really appreciate any help on this matter!

Answer 1

import 'package:flutter/material.dart';
import 'dart:async';
import 'package:flutter_tts/flutter_tts.dart';
class SpeakerClass extends StatefulWidget{
#override
State<StatefulWidget> createState() {
// TODO: implement createState
return _SpeakerClassState();
}
}
class _SpeakerClassState extends State<SpeakerClass>{
String text1 = 'eins';
String text2 = 'zwei';
String text3 = 'drei';
String text4 = 'vier';
String currentTtsString;
double ttsSpeechRate1 = 0.5;
double ttsSpeechRate2 = 1.0;
double currentSpeechRate;
FlutterTts flutterTts;
bool bolSpeaking = false;
Future playTtsString1() async {
bolSpeaking = true;
currentTtsString = text1;
currentSpeechRate = ttsSpeechRate1;
await runTextToSpeech(currentTtsString, currentSpeechRate);
return null;
}
Future playTtsString2() async {
bolSpeaking = true;
currentTtsString = text2;
currentSpeechRate = ttsSpeechRate2;
await runTextToSpeech(currentTtsString, currentSpeechRate);
return null;
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: FloatingActionButton (
backgroundColor: Colors.blue,
child: Icon(Icons.volume_up, color: Colors.white),
onPressed: () async {
// Play String 1
await playTtsString1();
// Check String 1 Finish
new Future.delayed(new Duration(milliseconds: 100), () async {
// loop until bolSpeaking = false
while (bolSpeaking) {
await Thread.sleep(100);
}
// play String 2
await playTtsString2();
}
},
)
);
}
}
Future<void> runTextToSpeech(String currentTtsString, double currentSpeechRate) async {
flutterTts = new FlutterTts();
await flutterTts.setLanguage("en-GB");
await flutterTts.setVolume(1.0);
await flutterTts.setPitch(1.0);
await flutterTts.isLanguageAvailable("en-GB");
await flutterTts.setSpeechRate(currentSpeechRate);
flutterTts.setCompletionHandler(() {
setState(() {
// The following code(s) will be called when the TTS finishes speaking
bolSpeaking = false;
});
});
flutterTts.speak(currentTtsString);
}

Answer 2

This should now work with the latest flutter_tts version.
You simply need to set awaitSpeakCompletion before the speaking happens.
You can update your run method like so:
Future<void> runTextToSpeech(String currentTtsString, double currentSpeechRate) async {
FlutterTts flutterTts;
flutterTts = new FlutterTts();
await flutterTts.awaitSpeakCompletion(true);
await flutterTts.setLanguage("en-GB");
await flutterTts.setVolume(1.0);
await flutterTts.setPitch(1.0);
await flutterTts.isLanguageAvailable("en-GB");
await flutterTts.setSpeechRate(currentSpeechRate);
await flutterTts.speak(currentTtsString);
}