MaterialApp({ title,theme: ThemeData({ primatySwatch, brightness, backgroundColor,.. }),home }

theme: ThemeData({ primatySwatch, brightness, backgroundColor,.. }) // Uygulamanın genel temasını belirler
            primatySwatch: Colors.blue            // Uygulamanın birincil rengi
            brightness: Brightness.dark | Brightness.light, // Uygulama karanlık mı parlak mı olacak.
            backgroundColor: Colors.blue          // Uygulama arkaplan rengi

 
import 'package:dynamic_theme/dynamic_theme.dart';
import 'package:dynamic_theme/theme_switcher_widgets.dart';
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return DynamicTheme(
        defaultBrightness: Brightness.light,
        data: (brightness) => ThemeData(
              primarySwatch: Colors.indigo,
              brightness: brightness,
            ),
        themedWidgetBuilder: (context, theme) {
          return MaterialApp(
            title: 'Flutter Demo',
            theme: theme,
            home: MyHomePage(title: 'Flutter Demo Home Page'),
          );
        });
  }
}
class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);
  final String title;
  @override
  _MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Easy Theme"),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            RaisedButton(
              onPressed: changeBrightness,
              child: const Text("Change brightness"),
            ),
            RaisedButton(
              onPressed: changeColor,
              child: const Text("Change color"),
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: showChooser,
        child: const Icon(Icons.add),
      ),
      bottomNavigationBar: BottomNavigationBar(
        items: [
          BottomNavigationBarItem(
              icon: Icon(Icons.insert_drive_file), title: Text("Tab 1")),
          BottomNavigationBarItem(
              icon: Icon(Icons.show_chart), title: Text("Tab 2")),
        ],
      ),
    );
  }
  void showChooser() {
    showDialog(
        context: context,
        builder: (context) {
          return BrightnessSwitcherDialog(
            onSelectedTheme: (brightness) {
              DynamicTheme.of(context).setBrightness(brightness);
            },
          );
        });
  }
  void changeBrightness() {
    DynamicTheme.of(context).setBrightness(
        Theme.of(context).brightness == Brightness.dark
            ? Brightness.light
            : Brightness.dark);
  }
  void changeColor() {
    DynamicTheme.of(context).setThemeData(ThemeData(
        primaryColor: Theme.of(context).primaryColor == Colors.indigo
            ? Colors.red
            : Colors.indigo));
  }
}

 
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
void main() {
  runApp(MyApp());
}
class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final appName = 'Custom Themes';
    return MaterialApp(
      title: appName,
      theme: ThemeData(
        // Define the default Brightness and Colors
        brightness: Brightness.dark,
        primaryColor: Colors.lightBlue[800],
        accentColor: Colors.cyan[600],
        // Define the default Font Family
        fontFamily: 'Montserrat',
        // Define the default TextTheme. Use this to specify the default
        // text styling for headlines, titles, bodies of text, and more.
        textTheme: TextTheme(
          headline: TextStyle(fontSize: 72.0, fontWeight: FontWeight.bold),
          title: TextStyle(fontSize: 36.0, fontStyle: FontStyle.italic),
          body1: TextStyle(fontSize: 14.0, fontFamily: 'Hind'),
        ),
      ),
      home: MyHomePage(
        title: appName,
      ),
    );
  }
}
class MyHomePage extends StatelessWidget {
  final String title;
  MyHomePage({Key key, @required this.title}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(title),
      ),
      body: Center(
        child: Container(
          color: Theme.of(context).accentColor,
          child: Text(
            'Text with a background color',
            style: Theme.of(context).textTheme.title,
          ),
        ),
      ),
      floatingActionButton: Theme(
        data: Theme.of(context).copyWith(accentColor: Colors.yellow),
        child: FloatingActionButton(
          onPressed: null,
          child: Icon(Icons.add),
        ),
      ),
    );
  }
}