handleMessage method
Implementation
@override
void handleMessage(
MapViewController mapViewController, Map<String, dynamic> payload) async {
var text = "${payload["text"]}";
var lang =
payload["lang"]?.toString().isNotEmpty == true ? payload["lang"] : null;
var pitch = payload["pitch"] > 0 ? payload["pitch"].toDouble() : null;
var volume = payload["volume"] > 0 ? payload['volume'].toDouble() : null;
var rate = payload["rate"] > 0 ? payload['rate'].toDouble() : null;
mapViewController._onSpeakAloudTextCallback?.call(OnSpeakAloudTextResult(
text: text, lang: lang, pitch: pitch, rate: rate, volume: volume));
}