What is flutter | Full Information ?

Here is full information about Flutter, a popular open-source UI toolkit for building natively compiled applications:

📌 Overview

Name: Flutter
Type: UI Toolkit / Framework for building cross-platform apps
Created By: Google
Initial Release: May 2017
Current Stable Version: Flutter 3.x (as of 2025)
License: BSD 3-Clause License (open-source)
Official Website: https://flutter.dev

🧠 What is Flutter?

Flutter is an open-source UI software development kit used to create natively compiled applications for mobile (iOS, Android), web, desktop (Windows, macOS, Linux), and embedded devices — all from a single codebase.

Flutter allows developers to build beautiful, fast, and expressive apps with a rich set of customizable widgets.

🎯 Key Features

1. Cross-Platform Development

Write once, run anywhere: build apps that work on multiple platforms with the same code.

2. Fast Development with Hot Reload

Hot reload allows developers to instantly see code changes in the app without restarting it, speeding up the development process.

3. Expressive and Flexible UI

Flutter offers a rich set of customizable widgets that follow specific design languages:
- Material Design (Google’s design system)
- Cupertino (Apple’s iOS design style)

4. Native Performance

Flutter compiles to native ARM machine code using the Dart language ahead-of-time (AOT) compilation.
Delivers high-performance apps that feel smooth and responsive.

5. Dart Programming Language

Flutter apps are written in Dart, an object-oriented language optimized for UI and client development.
Supports both ahead-of-time (AOT) and just-in-time (JIT) compilation.

6. Rich Set of Widgets

Widgets are everything in Flutter — buttons, text, images, layout models.
Highly customizable and composable.

7. Access to Native Features

Through platform channels, Flutter apps can communicate with native Android (Java/Kotlin) and iOS (Swift/Objective-C) code to access hardware and OS features.

🧱 Architecture

Flutter Engine: Written in C++, provides low-level rendering support using Skia graphics library.
Foundation Library: Written in Dart, provides basic classes and functions.
Widgets Layer: Builds UI components.
Flutter Framework: Rich set of libraries for UI, animation, gestures, and more.
Embedder: Integrates Flutter into different platforms.

⚙️ Development Setup

Requirements:

Install Flutter SDK from https://flutter.dev/docs/get-started/install
Install IDE plugins for VS Code or Android Studio
Set up device simulators or real devices (Android Emulator, iOS Simulator)

Basic Flutter app creation:

flutter create my_app
cd my_app
flutter run

🧰 Flutter Widgets Examples

Stateless Widget:

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(title: Text('Hello Flutter')),
        body: Center(child: Text('Welcome!')),
      ),
    );
  }
}

Stateful Widget:

class Counter extends StatefulWidget {
  @override
  _CounterState createState() => _CounterState();
}

class _CounterState extends State<Counter> {
  int _count = 0;

  void _increment() {
    setState(() {
      _count++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        Text('Count: $_count'),
        ElevatedButton(onPressed: _increment, child: Text('Increment')),
      ],
    );
  }
}