///////////////flutter dark/light theme with provider example
/************ main.dart ******************/
// add to pubspec.yaml - provider: ^4.0.5
import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import './theme_model.dart';

void main() => runApp(MultiProvider(
  providers: [
    ChangeNotifierProvider(  
      create: (_) => ThemeModel(),
    ),
  ],
  child: MyApp(),
));

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext bc) {
    return Consumer(
      builder: (BuildContext bc, ThemeModel themeModel, Widget w){
        return MaterialApp(
          title: 'title',
          theme: themeModel.currentTheme,
          home: Home(title:'title'),
        );});}}

class Home extends StatelessWidget{
final String title;
Home({this.title});
@override
Widget build(BuildContext context){
 return Scaffold(
  appBar: AppBar(title: Text(title)),
  body: Center(
    child:RaisedButton(child: Text("Change Theme"),
          onPressed:() => Provider.of(context, listen:false).toggleTheme(),
    ),));}}
/***************** theme_model.dart ****************/
import 'package:flutter/material.dart';
import './theme.dart';
enum ThemeType { Light, Dark }

class ThemeModel extends ChangeNotifier {
  ThemeData currentTheme = darkTheme;
  ThemeType _themeType = ThemeType.Dark;

  toggleTheme() {
    if (_themeType == ThemeType.Dark) {
      currentTheme = lightTheme;
      _themeType = ThemeType.Light;
      return notifyListeners();
    }
    if (_themeType == ThemeType.Light) {
      currentTheme = darkTheme;
      _themeType = ThemeType.Dark;
      return notifyListeners();
    }}}
/******************** theme.dart ******************/
import 'package:flutter/material.dart';
ThemeData darkTheme = ThemeData.dark().copyWith(
    primaryColor: Color(0xff1f655d),
    accentColor: Color(0xff40bf7a),
    textTheme: TextTheme(
        title: TextStyle(color: Color(0xff40bf7a)),
        subtitle: TextStyle(color: Colors.white),
        subhead: TextStyle(color: Color(0xff40bf7a))),
    appBarTheme: AppBarTheme(color: Color(0xff1f655d)));

ThemeData lightTheme = ThemeData.light().copyWith(
    primaryColor: Color(0xfff5f5f5),
    accentColor: Color(0xff40bf7a),
    textTheme: TextTheme(
        title: TextStyle(color: Colors.black54),
        subtitle: TextStyle(color: Colors.grey),
        subhead: TextStyle(color: Colors.white)),
    appBarTheme: AppBarTheme(
        color: Color(0xff1f655d),
        actionsIconTheme: IconThemeData(color: Colors.white)));