///////////////////////////////
theme switcher example
/////////////////////////////
////////////////////main.dart
import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import './theme_model.dart';

void main() => runApp(ChangeNotifierProvider<ThemeModel>(
    create: (_) => ThemeModel(), child: MyApp()));

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'Flutter Demo',
      theme: Provider.of<ThemeModel>(context).currentTheme,
      home: MyHomePage(title: 'Theme switch'),);}}

class MyHomePage extends StatelessWidget{
final String title;
MyHomePage({this.title});
Widget build(BuildContext context){
 return Scaffold(
     appBar: AppBar(
     title: Text(title)),
     body: Center(
child:RaisedButton(child: Text("Change Theme"),
 onPressed:(){
Provider.of<ThemeModel>(context, listen: false).toggleTheme();})));}}
////////////////////constant.dart
import 'package:flutter/material.dart';

const Color kPrimaryBackground = Color(0xff1f655d);
const Color kAccentBackground = Color(0xff2c8d82);
const Color kfloatingColor = Color(0xff35c168);
const Color kUserLabelColor = Color(0xff40bf7a);
const Color kLineColor = Color(0xff45827b);

const List<String> contextMenu = ["Settings", "About"];
FloatingActionButtonThemeData fabTheme = FloatingActionButtonThemeData(
  backgroundColor: kfloatingColor,
  foregroundColor: Colors.white,
);

ThemeData darkTheme = ThemeData.dark().copyWith(
    primaryColor: Color(0xff1f655d),
    accentColor: Color(0xff40bf7a),
    textTheme: TextTheme(
        headline6: TextStyle(color: Color(0xff40bf7a)),
        subtitle2: TextStyle(color: Colors.white),
        subtitle1: TextStyle(color: Color(0xff40bf7a))),

    appBarTheme: AppBarTheme(color: Color(0xff1f655d)));

ThemeData lightTheme = ThemeData.light().copyWith(
    primaryColor: Color(0xfff5f5f5),
    accentColor: Color(0xff40bf7a),
    textTheme: TextTheme(
        headline6: TextStyle(color: Colors.black54),
        subtitle2: TextStyle(color: Colors.grey),
        subtitle1: TextStyle(color: Colors.white)),
    appBarTheme: AppBarTheme(
        color: Color(0xff1f655d),
        actionsIconTheme: IconThemeData(color: Colors.white)));

enum ThemeType { Light, Dark }
///////////////////theme_model.dart