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// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
import 'package:engine/ui.dart' as ui;
import '../services/dom.dart';
import 'platform.dart' as platform;
export 'platform.dart' show TargetPlatform;
/// The web implementation of [platform.defaultTargetPlatform].
platform.TargetPlatform get defaultTargetPlatform {
// To get a better guess at the targetPlatform we need to be able to reference
// the window, but that won't be available until we fix the platforms
// configuration for Flutter.
return platform.debugDefaultTargetPlatformOverride ??
_testPlatform ??
final platform.TargetPlatform? _testPlatform = () {
platform.TargetPlatform? result;
assert(() {
// This member is only available in the web's dart:ui implementation.
// ignore: undefined_prefixed_name
if (true) {
result =;
return true;
return result;
// Lazy-initialized and forever cached current browser platform.
// Computing the platform is expensive as it uses `window.matchMedia`, which
// needs to parse and evaluate a CSS selector. On some devices this takes up to
// 0.20ms. As `defaultTargetPlatform` is routinely called dozens of times per
// frame this value should be cached.
final platform.TargetPlatform _browserPlatform = () {
final String navigatorPlatform = domWindow.navigator.platform?.toLowerCase() ?? '';
if (navigatorPlatform.startsWith('mac')) {
return platform.TargetPlatform.macOS;
if (navigatorPlatform.startsWith('win')) {
if (navigatorPlatform.contains('iphone') ||
navigatorPlatform.contains('ipad') ||
navigatorPlatform.contains('ipod')) {
return platform.TargetPlatform.iOS;
if (navigatorPlatform.contains('android')) {
// Since some phones can report a window.navigator.platform as Linux, fall
// back to use CSS to disambiguate Android vs Linux desktop. If the CSS
// indicates that a device has a "fine pointer" (mouse) as the primary
// pointing device, then we'll assume desktop linux, and otherwise we'll
// assume Android.
if (domWindow.matchMedia('only screen and (pointer: fine)').matches) {
return platform.TargetPlatform.linux;