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:

• Install Flutter
• Flutter documentation
• Stable channel API reference documentation
• Main channel API reference documentation
• Contributing to Flutter

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.

Offline HTML documentation ZIP bundles:

• Stable channel
• Main channel

Or, you can add Flutter to the open-source Zeal app using the following XML configurations. Follow the instructions in the application for adding a feed.

• Stable channel Zeal XML configuration URL: api.flutter.dev/offline/flutter.xml
• Main channel Zeal XML configuration URL: main-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:

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:

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:

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.

Libraries

animation

The Flutter animation system.

cupertino

Flutter widgets implementing the current iOS design language.

foundation

Core Flutter framework primitives.

gestures

The Flutter gesture recognizers.

material

Flutter widgets implementing Material Design.

painting

The Flutter painting library.

physics

Simple one-dimensional physics simulations, such as springs, friction, and gravity, for use in user interface animations.

rendering

The Flutter rendering tree.

scheduler

The Flutter Scheduler library.

semantics

The Flutter semantics package.

services

Platform services exposed to Flutter apps.

widget_previews

The Flutter widget preview annotations and data classes.

widgets

The Flutter widgets framework.

Dart

dart:ui

Built-in types and core primitives for a Flutter application.

dart:ui_web

Core

dart:async

Support for asynchronous programming, with classes such as Future and Stream.

dart:collection

Classes and utilities that supplement the collection support in dart:core.

dart:convert

Encoders and decoders for converting between different data representations, including JSON and UTF-8.

dart:core

Built-in types, collections, and other core functionality for every Dart program.

dart:developer

Interact with developer tools such as the debugger and inspector.

dart:math

Mathematical constants and functions, plus a random number generator.

dart:typed_data

Lists that efficiently handle fixed sized data (for example, unsigned 8 byte integers) and SIMD numeric types.

VM

dart:ffi

Foreign Function Interface for interoperability with the C programming language.

dart:io

File, socket, HTTP, and other I/O support for non-web applications.

dart:isolate

Concurrent programming using isolates: independent workers that are similar to threads but don't share memory, communicating only via messages.

Web

package:web open_in_new

This package exposes browser APIs. It's intended to replace dart:html and similar Dart SDK libraries. It will support access to browser APIs from Dart code compiled to either JavaScript or WebAssembly.

dart:js_interop

Interoperability, "interop" for short, with JavaScript and browser APIs.

dart:js_interop_unsafe

Utility methods to manipulate JavaScript objects dynamically.

Web (Legacy)

dart:html

HTML elements and other resources for web-based applications that need to interact with the browser and the DOM (Document Object Model).

dart:js

Low-level support for interoperating with JavaScript.

platform_integration

android

Flutter Android Embedder.

ios

FlutteriOS Embedder.

linux

Flutter Linux Embedder.

macos

Flutter macOS Embedder.

windows

Flutter Windows Embedder.

flutter_test

flutter_test

Testing library for flutter, built on top of package:test.

flutter_driver

driver_extension

This library provides a Dart VM service extension that is required for tests that use package:flutter_driver to drive applications from a separate process, similar to Selenium (web), Espresso (Android) and UI Automation (iOS).

flutter_driver

Provides API to test Flutter applications that run on real devices and emulators.

Flutter

flutter_gpu

gpu

Flutter GPU is a low level API for building rendering packages from scratch.

flutter_localizations

flutter_localizations

Localizations for the Flutter library.

flutter_web_plugins

flutter_web_plugins

The platform channels and plugin registry implementations for the web implementations of Flutter plugins.

url_strategy

leak_tracker_flutter_testing

leak_tracker_flutter_testing

async

async

Utilities that expand on the asynchronous features of the dart:async library.

boolean_selector

boolean_selector

characters

characters

String operations based on characters (Unicode grapheme clusters).

clock

clock

collection

algorithms

Import collection.dart instead.

collection

equality

Import collection.dart instead.

iterable_zip

Import collection.dart instead.

priority_queue

Import collection.dart instead.

wrappers

Import collection.dart instead.

crypto

crypto

fake_async

fake_async

file

chroot

A file system that provides a view into another FileSystem via a path.

file

Core interfaces containing the abstract FileSystem interface definition and all associated types used by FileSystem.

local

A local file system implementation. This relies on the use of dart:io and is thus not suitable for use in the browser.

memory

An implementation of FileSystem that exists entirely in memory with an internal representation loosely based on the Filesystem Hierarchy Standard.

integration_test

common

integration_test

integration_test_driver

integration_test_driver_extended

intl

date_symbol_data_custom

API to allow setting Date/Time formatting in a custom way.

date_symbol_data_file

This file should be imported, along with date_format.dart in order to read locale data from files in the file system.

date_symbol_data_http_request

This file should be imported, along with date_format.dart in order to read locale data via http requests to a web server.

date_symbol_data_local

Date/time formatting symbols for all locales.

date_symbols

date_time_patterns

Date/time formatting symbols for a large subset of locales.

find_locale

intl

This library provides internationalization and localization. This includes message formatting and replacement, date and number formatting and parsing, and utilities for working with Bidirectional text.

intl_default

This provides facilities for Internationalization that are only available when running in the web browser. You should import only one of this or intl_standalone.dart. Right now the only thing provided here is the ability to find the default locale from the browser.

intl_standalone

This provides facilities for Internationalization that are only available when running standalone. You should import only one of this or intl_browser.dart. Right now the only thing provided here is finding the operating system locale.

locale

Provides access to the Locale class.

message_format

MessageFormat prepares strings for display to users, with optional arguments (variables/placeholders). The arguments can occur in any order, which is necessary for translation into languages with different grammars. It supports syntax to represent plurals and select options.

message_lookup_by_library

Message/plural format library with locale support. This can have different implementations based on the mechanism for finding the localized versions of messages. This version expects them to be in a library named e.g. 'messages_en_US'. The prefix is set in the "initializeMessages" call, which must be made for a locale before any lookups can be done.

number_symbols

number_symbols_data

Date/time formatting symbols for all locales.

leak_tracker

leak_tracker

leak_tracker_testing

leak_tracker_testing

listen

listen

Notify state changes to interested listeners.

matcher

expect

matcher

Support for specifying test expectations, such as for unit tests.

material_color_utilities

blend/blend

contrast/contrast

dislike/dislike_analyzer

dynamiccolor/dynamic_color

dynamiccolor/dynamic_scheme

dynamiccolor/material_dynamic_colors

dynamiccolor/src/contrast_curve

dynamiccolor/src/tone_delta_pair

dynamiccolor/variant

hct/cam16

hct/hct

hct/src/hct_solver

hct/viewing_conditions

material_color_utilities

palettes/core_palette

palettes/core_palettes

palettes/tonal_palette

quantize/quantizer

quantize/quantizer_celebi

quantize/quantizer_map

quantize/quantizer_wsmeans

quantize/quantizer_wu

quantize/src/point_provider

quantize/src/point_provider_lab

scheme/scheme

scheme/scheme_content

scheme/scheme_expressive

scheme/scheme_fidelity

scheme/scheme_fruit_salad

scheme/scheme_monochrome

scheme/scheme_neutral

scheme/scheme_rainbow

scheme/scheme_tonal_spot

scheme/scheme_vibrant

score/score

temperature/temperature_cache

utils/color_utils

utils/math_utils

utils/string_utils

meta

dart2js

Constants for use in metadata annotations to provide hints to dart2js, which is the compiler used by dart compile js.

meta

Annotations that developers can use to express the intentions that otherwise can't be deduced by statically analyzing the source code.

meta_meta

Annotations that describe the intended use of other annotations.

path

path

A comprehensive, cross-platform path manipulation library.

platform

platform

Properties of the current platform.

testing

Platform information, and mocking of that information for tests.

process

process

source_span

source_span

stack_trace

stack_trace

stream_channel

isolate_channel

stream_channel

string_scanner

string_scanner

A library for parsing strings using a sequence of patterns.

sync_http

sync_http

term_glyph

term_glyph

test_api

backend

fake

hooks

hooks_testing

scaffolding

test_api

vector_math

hash

vector_math

A library containing different type of vector operations for use in games, simulations, or rendering.

vector_math_64

A library containing different type of vector operations for use in games, simulations, or rendering.

vector_math_geometry

A library containing geometry generators (like CubeGenerator, SphereGenerator and CylinderGenerator) and filters (BarycentricFilter, ColorFilter and InvertFilter).

vector_math_lists

A library for working with lists of vectors in a memory efficient way.

vector_math_operations

A library containing matrix operations (Matrix44Operations) that can be performed on Float32List instances and SIMD optimized operations (Matrix44SIMDOperations) that can be performed on Float32x4List instances.

vm_service

utils

vm_service

vm_service_io

web

helpers

web

webdriver

async_core

async_html

async_io

core

io

support/async

support/firefox_profile

support/stdio_stepper

sync_core

sync_io