flutter_ffmpeg/example/lib/flutter_ffmpeg_test_app.dart

import 'package:flutter/material.dart';
import 'package:flutter_ffmpeg_example/flutter_ffmpeg_test_app_state.dart';

void main() => runApp(FlutterFFmpegTestApp());

class FlutterFFmpegTestApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(
        primaryColor: Color(0xFFF46842),
      ),
      home: MainPage(),
    );
  }
}

class MainPage extends StatefulWidget {
  @override
  FlutterFFmpegTestAppState createState() => new FlutterFFmpegTestAppState();
}

class DecoratedTabBar extends StatelessWidget implements PreferredSizeWidget {
  DecoratedTabBar({@required this.tabBar, @required this.decoration});

  final TabBar tabBar;
  final BoxDecoration decoration;

  @override
  Size get preferredSize => tabBar.preferredSize;

  @override
  Widget build(BuildContext context) {
    return Stack(
      children: [
        Positioned.fill(child: Container(decoration: decoration)),
        tabBar,
      ],
    );
  }
}