| # Welcome to the Flutter API reference documentation! |
| |
| Flutter is Google's SDK for crafting beautiful, fast user experiences for |
| mobile, web, and desktop from a single codebase. Flutter works with existing |
| code, is used by developers and organizations around the world, and is free |
| and open source. |
| |
| This API reference covers all libraries that are exported by the Flutter |
| SDK. |
| |
| ## More Documentation |
| |
| This site hosts Flutter's API documentation. Other documentation can be found at |
| the following locations: |
| |
| * [flutter.dev](https://flutter.dev) (main site) |
| * [Installation](https://flutter.dev/docs/get-started/install) |
| * [Codelabs](https://flutter.dev/docs/codelabs) |
| * [Contributing to Flutter](https://github.com/flutter/flutter/blob/master/CONTRIBUTING.md) |
| |
| ## Offline Documentation |
| |
| In addition to the online sites above, Flutter's documentation can be downloaded |
| as an HTML documentation ZIP file for use when offline or when you have a poor |
| internet connection. |
| |
| **Warning: the offline documentation files are quite large, approximately 700 MB |
| to 900 MB.** |
| |
| Offline HTML documentation ZIP bundles: |
| |
| * [Stable channel](https://api.flutter.dev/offline/flutter.docs.zip) |
| * [Master channel](https://master-api.flutter.dev/offline/flutter.docs.zip) |
| |
| Or, you can add Flutter to the open-source [Zeal](https://zealdocs.org/) app |
| using the following XML configurations. Follow the instructions in the |
| application for adding a feed. |
| |
| * Stable channel Zeal XML configuration URL: |
| <https://api.flutter.dev/offline/flutter.xml> |
| * Master channel Zeal XML configuration URL: |
| <https://master-api.flutter.dev/offline/flutter.xml> |
| |
| ## Importing a Library |
| |
| ### Framework Libraries |
| |
| Libraries in the "Libraries" section below (or in the left navigation) are part |
| of the core Flutter framework and are imported using |
| `'package:flutter/<library>.dart'`, like so: |
| |
| ```dart |
| import 'package:flutter/material.dart'; |
| import 'package:flutter/services.dart'; |
| ``` |
| |
| ### Dart Libraries |
| |
| Libraries in the "Dart" section exist in the `dart:` namespace and are imported |
| using `'dart:<library>'`, like so: |
| |
| ```dart |
| import 'dart:async'; |
| import 'dart:ui'; |
| ``` |
| |
| Except for `'dart:core'`, you must import a Dart library before you can use it. |
| |
| ### Supporting Libraries |
| |
| Libraries in other sections are supporting libraries that ship with Flutter. |
| They are organized by package and are imported using |
| `'package:<package>/<library>.dart'`, like so: |
| |
| ```dart |
| import 'package:flutter_test/flutter_test.dart'; |
| import 'package:file/local.dart'; |
| ``` |
| |
| ## Packages on pub.dev |
| |
| Flutter has a rich ecosystem of packages that have been contributed by the |
| Flutter team and the broader open source community to a central repository. |
| Among the thousands of packages, you'll find support for Firebase, Google |
| Fonts, hardware services like Bluetooth and camera, new widgets and |
| animations, and integration with other popular web services. You can browse |
| those packages at [pub.dev](https://pub.dev). |