Add Flutter text to speech demo (#1087)

flutter-examples/tts/lib/main.dart

@@ -0,0 +1,69 @@
+// Copyright (c)  2024  Xiaomi Corporation
+import 'package:flutter/material.dart';
+
+import './tts.dart';
+import './info.dart';
+
+void main() {
+  runApp(const MyApp());
+}
+
+class MyApp extends StatelessWidget {
+  const MyApp({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      title: 'Next-gen Kaldi flutter demo',
+      theme: ThemeData(
+        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
+        useMaterial3: true,
+      ),
+      home: const MyHomePage(title: 'Next-gen Kaldi with Flutter'),
+    );
+  }
+}
+
+class MyHomePage extends StatefulWidget {
+  const MyHomePage({super.key, required this.title});
+
+  final String title;
+
+  @override
+  State<MyHomePage> createState() => _MyHomePageState();
+}
+
+class _MyHomePageState extends State<MyHomePage> {
+  int _currentIndex = 0;
+  final List<Widget> _tabs = [
+    TtsScreen(),
+    InfoScreen(),
+  ];
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        title: Text(widget.title),
+      ),
+      body: _tabs[_currentIndex],
+      bottomNavigationBar: BottomNavigationBar(
+        currentIndex: _currentIndex,
+        onTap: (int index) {
+          setState(() {
+            _currentIndex = index;
+          });
+        },
+        items: [
+          BottomNavigationBarItem(
+            icon: Icon(Icons.home),
+            label: 'Home',
+          ),
+          BottomNavigationBarItem(
+            icon: Icon(Icons.info),
+            label: 'Info',
+          ),
+        ],
+      ),
+    );
+  }
+}