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// Copyright 2018 The Chromium 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:flutter/rendering.dart';
import 'package:flutter/widgets.dart';
import 'button.dart';
import 'colors.dart';
import 'icons.dart';
import 'interface_level.dart';
import 'localizations.dart';
import 'route.dart';
import 'theme.dart';
/// An application that uses Cupertino design.
/// A convenience widget that wraps a number of widgets that are commonly
/// required for an iOS-design targeting application. It builds upon a
/// [WidgetsApp] by iOS specific defaulting such as fonts and scrolling
/// physics.
/// The [CupertinoApp] configures the top-level [Navigator] to search for routes
/// in the following order:
/// 1. For the `/` route, the [home] property, if non-null, is used.
/// 2. Otherwise, the [routes] table is used, if it has an entry for the route.
/// 3. Otherwise, [onGenerateRoute] is called, if provided. It should return a
/// non-null value for any _valid_ route not handled by [home] and [routes].
/// 4. Finally if all else fails [onUnknownRoute] is called.
/// If [home], [routes], [onGenerateRoute], and [onUnknownRoute] are all null,
/// and [builder] is not null, then no [Navigator] is created.
/// This widget also configures the observer of the top-level [Navigator] (if
/// any) to perform [Hero] animations.
/// Use this widget with caution on Android since it may produce behaviors
/// Android users are not expecting such as:
/// * Pages will be dismissible via a back swipe.
/// * Scrolling past extremities will trigger iOS-style spring overscrolls.
/// * The San Francisco font family is unavailable on Android and can result
/// in undefined font behavior.
/// See also:
/// * [CupertinoPageScaffold], which provides a standard page layout default
/// with nav bars.
/// * [Navigator], which is used to manage the app's stack of pages.
/// * [CupertinoPageRoute], which defines an app page that transitions in an
/// iOS-specific way.
/// * [WidgetsApp], which defines the basic app elements but does not depend
/// on the Cupertino library.
class CupertinoApp extends StatefulWidget {
/// Creates a CupertinoApp.
/// At least one of [home], [routes], [onGenerateRoute], or [builder] must be
/// non-null. If only [routes] is given, it must include an entry for the
/// [Navigator.defaultRouteName] (`/`), since that is the route used when the
/// application is launched with an intent that specifies an otherwise
/// unsupported route.
/// This class creates an instance of [WidgetsApp].
/// The boolean arguments, [routes], and [navigatorObservers], must not be null.
const CupertinoApp({
Key key,
this.routes = const <String, WidgetBuilder>{},
this.navigatorObservers = const <NavigatorObserver>[],
this.title = '',
this.supportedLocales = const <Locale>[Locale('en', 'US')],
this.showPerformanceOverlay = false,
this.checkerboardRasterCacheImages = false,
this.checkerboardOffscreenLayers = false,
this.showSemanticsDebugger = false,
this.debugShowCheckedModeBanner = true,
}) : assert(routes != null),
assert(navigatorObservers != null),
assert(title != null),
assert(showPerformanceOverlay != null),
assert(checkerboardRasterCacheImages != null),
assert(checkerboardOffscreenLayers != null),
assert(showSemanticsDebugger != null),
assert(debugShowCheckedModeBanner != null),
super(key: key);
/// {@macro flutter.widgets.widgetsApp.navigatorKey}
final GlobalKey<NavigatorState> navigatorKey;
/// {@macro flutter.widgets.widgetsApp.home}
final Widget home;
/// The top-level [CupertinoTheme] styling.
/// A null [theme] or unspecified [theme] attributes will default to iOS
/// system values.
final CupertinoThemeData theme;
/// The application's top-level routing table.
/// When a named route is pushed with [Navigator.pushNamed], the route name is
/// looked up in this map. If the name is present, the associated
/// [WidgetBuilder] is used to construct a [CupertinoPageRoute] that performs
/// an appropriate transition, including [Hero] animations, to the new route.
/// {@macro flutter.widgets.widgetsApp.routes}
final Map<String, WidgetBuilder> routes;
/// {@macro flutter.widgets.widgetsApp.initialRoute}
final String initialRoute;
/// {@macro flutter.widgets.widgetsApp.onGenerateRoute}
final RouteFactory onGenerateRoute;
/// {@macro flutter.widgets.widgetsApp.onUnknownRoute}
final RouteFactory onUnknownRoute;
/// {@macro flutter.widgets.widgetsApp.navigatorObservers}
final List<NavigatorObserver> navigatorObservers;
/// {@macro flutter.widgets.widgetsApp.builder}
final TransitionBuilder builder;
/// {@macro flutter.widgets.widgetsApp.title}
/// This value is passed unmodified to [WidgetsApp.title].
final String title;
/// {@macro flutter.widgets.widgetsApp.onGenerateTitle}
/// This value is passed unmodified to [WidgetsApp.onGenerateTitle].
final GenerateAppTitle onGenerateTitle;
/// {@macro flutter.widgets.widgetsApp.color}
final Color color;
/// {@macro flutter.widgets.widgetsApp.locale}
final Locale locale;
/// {@macro flutter.widgets.widgetsApp.localizationsDelegates}
final Iterable<LocalizationsDelegate<dynamic>> localizationsDelegates;
/// {@macro flutter.widgets.widgetsApp.localeListResolutionCallback}
/// This callback is passed along to the [WidgetsApp] built by this widget.
final LocaleListResolutionCallback localeListResolutionCallback;
/// {@macro flutter.widgets.widgetsApp.localeResolutionCallback}
/// This callback is passed along to the [WidgetsApp] built by this widget.
final LocaleResolutionCallback localeResolutionCallback;
/// {@macro flutter.widgets.widgetsApp.supportedLocales}
/// It is passed along unmodified to the [WidgetsApp] built by this widget.
final Iterable<Locale> supportedLocales;
/// Turns on a performance overlay.
/// See also:
/// * <>
final bool showPerformanceOverlay;
/// Turns on checkerboarding of raster cache images.
final bool checkerboardRasterCacheImages;
/// Turns on checkerboarding of layers rendered to offscreen bitmaps.
final bool checkerboardOffscreenLayers;
/// Turns on an overlay that shows the accessibility information
/// reported by the framework.
final bool showSemanticsDebugger;
/// {@macro flutter.widgets.widgetsApp.debugShowCheckedModeBanner}
final bool debugShowCheckedModeBanner;
_CupertinoAppState createState() => _CupertinoAppState();
/// The [HeroController] used for Cupertino page transitions.
/// Used by [CupertinoTabView] and [CupertinoApp].
static HeroController createCupertinoHeroController() =>
HeroController(); // Linear tweening.
class _AlwaysCupertinoScrollBehavior extends ScrollBehavior {
Widget buildViewportChrome(BuildContext context, Widget child, AxisDirection axisDirection) {
// Never build any overscroll glow indicators.
return child;
ScrollPhysics getScrollPhysics(BuildContext context) {
return const BouncingScrollPhysics();
class _CupertinoAppState extends State<CupertinoApp> {
HeroController _heroController;
void initState() {
_heroController = CupertinoApp.createCupertinoHeroController();
void didUpdateWidget(CupertinoApp oldWidget) {
if (widget.navigatorKey != oldWidget.navigatorKey) {
// If the Navigator changes, we have to create a new observer, because the
// old Navigator won't be disposed (and thus won't unregister with its
// observers) until after the new one has been created (because the
// Navigator has a GlobalKey).
_heroController = CupertinoApp.createCupertinoHeroController();
List<NavigatorObserver> _navigatorObservers;
void _updateNavigator() {
if (widget.home != null ||
widget.routes.isNotEmpty ||
widget.onGenerateRoute != null ||
widget.onUnknownRoute != null) {
_navigatorObservers = List<NavigatorObserver>.from(widget.navigatorObservers)
} else {
_navigatorObservers = const <NavigatorObserver>[];
// Combine the default localization for Cupertino with the ones contributed
// by the localizationsDelegates parameter, if any. Only the first delegate
// of a particular LocalizationsDelegate.type is loaded so the
// localizationsDelegate parameter can be used to override
// _CupertinoLocalizationsDelegate.
Iterable<LocalizationsDelegate<dynamic>> get _localizationsDelegates sync* {
if (widget.localizationsDelegates != null)
yield* widget.localizationsDelegates;
yield DefaultCupertinoLocalizations.delegate;
Widget build(BuildContext context) {
final CupertinoThemeData effectiveThemeData = widget.theme ?? const CupertinoThemeData();
return ScrollConfiguration(
behavior: _AlwaysCupertinoScrollBehavior(),
child: CupertinoUserInterfaceLevel(
data: CupertinoUserInterfaceLevelData.base,
child: CupertinoTheme(
data: effectiveThemeData,
child: Builder(
builder: (BuildContext context) {
return WidgetsApp(
key: GlobalObjectKey(this),
navigatorKey: widget.navigatorKey,
navigatorObservers: _navigatorObservers,
pageRouteBuilder: <T>(RouteSettings settings, WidgetBuilder builder) =>
CupertinoPageRoute<T>(settings: settings, builder: builder),
home: widget.home,
routes: widget.routes,
initialRoute: widget.initialRoute,
onGenerateRoute: widget.onGenerateRoute,
onUnknownRoute: widget.onUnknownRoute,
builder: widget.builder,
title: widget.title,
onGenerateTitle: widget.onGenerateTitle,
textStyle: effectiveThemeData.textTheme.textStyle,
color: CupertinoDynamicColor.resolve(widget.color ?? effectiveThemeData.primaryColor, context),
locale: widget.locale,
localizationsDelegates: _localizationsDelegates,
localeResolutionCallback: widget.localeResolutionCallback,
localeListResolutionCallback: widget.localeListResolutionCallback,
supportedLocales: widget.supportedLocales,
showPerformanceOverlay: widget.showPerformanceOverlay,
checkerboardRasterCacheImages: widget.checkerboardRasterCacheImages,
checkerboardOffscreenLayers: widget.checkerboardOffscreenLayers,
showSemanticsDebugger: widget.showSemanticsDebugger,
debugShowCheckedModeBanner: widget.debugShowCheckedModeBanner,
inspectorSelectButtonBuilder: (BuildContext context, VoidCallback onPressed) {
return CupertinoButton.filled(
child: const Icon(,
size: 28.0,
color: CupertinoColors.white,
onPressed: onPressed,
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