_AssertionError ('package:flutter/src/widgets/app.dart': Failed assertion: line 231 pos 10

Tengo este problem.
Launching lib\main.dart on SM G955F in debug mode...
√  Built build\app\outputs\flutter-apk\app-debug.apk.
Connecting to VM Service at ws://<IP_ADDRESS>:63680/eZQ3SDCOK4E=/ws
════════ Exception caught by widgets library ═══════════════════════════════════
The following assertion was thrown building MaterialApp(dirty, state: _MaterialAppState#740d6):
If no route is provided using home, routes, onGenerateRoute, or onUnknownRoute, a non-null callback for the builder property must be provided, and the other navigator-related properties, navigatorKey, initialRoute, and navigatorObservers, must have their initial values (null, null, and the empty list, respectively).

'package:flutter/src/widgets/app.dart':
Failed assertion: line 235 pos 11: '(home != null ||
                  routes.isNotEmpty ||
                  onGenerateRoute != null ||
                  onUnknownRoute != null) ||
              (builder != null &&
                  navigatorKey == null &&
                  initialRoute == null &&
                  navigatorObservers.isEmpty)'

Either the assertion indicates an error in the framework itself, or we should provide substantially more information in this error message to help you determine and fix the underlying cause.
In either case, please report this assertion by filing a bug on GitHub:
  https://github.com/flutter/flutter/issues/new?template=2_bug.md

The relevant error-causing widget was
MaterialApp
When the exception was thrown, this was the stack
#2      new WidgetsApp
#3      _MaterialAppState._buildWidgetApp
#4      _MaterialAppState.build
#5      StatefulElement.build
#6      ComponentElement.performRebuild
...
════════════════════════════════════════════════════════════════════════════════
Lost connection to device.
Exited (sigterm)

codigo
})  : assert(navigatorObservers != null),
        assert(routes != null),
        assert(
          home == null || onGenerateInitialRoutes == null,
          'If onGenerateInitialRoutes is specified, the home argument will be '
          'redundant.',
        ),
        assert(
          home == null || !routes.containsKey(Navigator.defaultRouteName),
          'If the home property is specified, the routes table '
          'cannot include an entry for "/", since it would be redundant.',
        ),
        assert(
          builder != null ||
              home != null ||
              routes.containsKey(Navigator.defaultRouteName) ||
              onGenerateRoute != null ||
              onUnknownRoute != null,
          'Either the home property must be specified, '
          'or the routes table must include an entry for "/", '
          'or there must be on onGenerateRoute callback specified, '
          'or there must be an onUnknownRoute callback specified, '
          'or the builder property must be specified, '
          'because otherwise there is nothing to fall back on if the '
          'app is started with an intent that specifies an unknown route.',
        ),
        assert(
          (home != null ||
                  routes.isNotEmpty ||
                  onGenerateRoute != null ||
                  onUnknownRoute != null) ||
              (builder != null &&
                  navigatorKey == null &&
                  initialRoute == null &&
                  navigatorObservers.isEmpty),
          'If no route is provided using '
          'home, routes, onGenerateRoute, or onUnknownRoute, '
          'a non-null callback for the builder property must be provided, '
          'and the other navigator-related properties, '
          'navigatorKey, initialRoute, and navigatorObservers, '
          'must have their initial values '
          '(null, null, and the empty list, respectively).',
        ),
        assert(
          builder != null ||
              onGenerateRoute != null ||
              pageRouteBuilder != null,
          'If neither builder nor onGenerateRoute are provided, the '
          'pageRouteBuilder must be specified so that the default handler '
          'will know what kind of PageRoute transition to build.',
        ),
        assert(title != null),
        assert(color != null),
        assert(supportedLocales != null && supportedLocales.isNotEmpty),
        assert(showPerformanceOverlay != null),
        assert(checkerboardRasterCacheImages != null),
        assert(checkerboardOffscreenLayers != null),
        assert(showSemanticsDebugger != null),
        assert(debugShowCheckedModeBanner != null),
        assert(debugShowWidgetInspector != null),
        routeInformationProvider = null,
        routeInformationParser = null,
        routerDelegate = null,
        backButtonDispatcher = null,
        super(key: key);

@matiariel
Can you provide flutter doctor -v and a complete minimal reproducible code sample that we can directly copy paste and run that shows this issue ?
Thanks.

Code completo
import 'dart:collection' show HashMap;
import 'package:flutter/foundation.dart';
import 'package:flutter/rendering.dart';
import 'package:flutter/services.dart';
import 'actions.dart';
import 'banner.dart';
import 'basic.dart';
import 'binding.dart';
import 'default_text_editing_actions.dart';
import 'default_text_editing_shortcuts.dart';
import 'focus_traversal.dart';
import 'framework.dart';
import 'localizations.dart';
import 'media_query.dart';
import 'navigator.dart';
import 'pages.dart';
import 'performance_overlay.dart';
import 'restoration.dart';
import 'router.dart';
import 'scrollable.dart';
import 'semantics_debugger.dart';
import 'shortcuts.dart';
import 'text.dart';
import 'title.dart';
import 'widget_inspector.dart';
export 'dart:ui' show Locale;
/// The signature of [WidgetsApp.localeListResolutionCallback].
///
/// A [LocaleListResolutionCallback] is responsible for computing the locale of the app's
/// [Localizations] object when the app starts and when user changes the list of
/// locales for the device.
///
/// The [locales] list is the device's preferred locales when the app started, or the
/// device's preferred locales the user selected after the app was started. This list
/// is in order of preference. If this list is null or empty, then Flutter has not yet
/// received the locale information from the platform. The [supportedLocales] parameter
/// is just the value of [WidgetsApp.supportedLocales].
///
/// See also:
///
///  * [LocaleResolutionCallback], which takes only one default locale (instead of a list)
///    and is attempted only after this callback fails or is null. [LocaleListResolutionCallback]
///    is recommended over [LocaleResolutionCallback].
typedef LocaleListResolutionCallback = Locale? Function(
List? locales, Iterable supportedLocales);
/// {@template flutter.widgets.LocaleResolutionCallback}
/// The signature of [WidgetsApp.localeResolutionCallback].
///
/// It is recommended to provide a [LocaleListResolutionCallback] instead of a
/// [LocaleResolutionCallback] when possible, as [LocaleResolutionCallback] only
/// receives a subset of the information provided in [LocaleListResolutionCallback].
///
/// A [LocaleResolutionCallback] is responsible for computing the locale of the app's
/// [Localizations] object when the app starts and when user changes the default
/// locale for the device after [LocaleListResolutionCallback] fails or is not provided.
///
/// This callback is also used if the app is created with a specific locale using
/// the [new WidgetsApp] locale parameter.
///
/// The [locale] is either the value of [WidgetsApp.locale], or the device's default
/// locale when the app started, or the device locale the user selected after the app
/// was started. The default locale is the first locale in the list of preferred
/// locales. If [locale] is null, then Flutter has not yet received the locale
/// information from the platform. The [supportedLocales] parameter is just the value of
/// [WidgetsApp.supportedLocales].
///
/// See also:
///
///  * [LocaleListResolutionCallback], which takes a list of preferred locales (instead of one locale).
///    Resolutions by [LocaleListResolutionCallback] take precedence over [LocaleResolutionCallback].
/// {@endtemplate}
typedef LocaleResolutionCallback = Locale? Function(
Locale? locale, Iterable supportedLocales);
/// The signature of [WidgetsApp.onGenerateTitle].
///
/// Used to generate a value for the app's [Title.title], which the device uses
/// to identify the app for the user. The context includes the [WidgetsApp]'s
/// [Localizations] widget so that this method can be used to produce a
/// localized title.
///
/// This function must not return null.
typedef GenerateAppTitle = String Function(BuildContext context);
/// The signature of [WidgetsApp.pageRouteBuilder].
///
/// Creates a [PageRoute] using the given [RouteSettings] and [WidgetBuilder].
typedef PageRouteFactory = PageRoute Function(
RouteSettings settings, WidgetBuilder builder);
/// The signature of [WidgetsApp.onGenerateInitialRoutes].
///
/// Creates a series of one or more initial routes.
typedef InitialRouteListFactory = List<Route> Function(
String initialRoute);
/// A convenience widget that wraps a number of widgets that are commonly
/// required for an application.
///
/// One of the primary roles that [WidgetsApp] provides is binding the system
/// back button to popping the [Navigator] or quitting the application.
///
/// It is used by both [MaterialApp] and [CupertinoApp] to implement base
/// functionality for an app.
///
/// Find references to many of the widgets that [WidgetsApp] wraps in the "See
/// also" section.
///
/// See also:
///
///  * [CheckedModeBanner], which displays a [Banner] saying "DEBUG" when
///    running in checked mode.
///  * [DefaultTextStyle], the text style to apply to descendant [Text] widgets
///    without an explicit style.
///  * [MediaQuery], which establishes a subtree in which media queries resolve
///    to a [MediaQueryData].
///  * [Localizations], which defines the [Locale] for its child.
///  * [Title], a widget that describes this app in the operating system.
///  * [Navigator], a widget that manages a set of child widgets with a stack
///    discipline.
///  * [Overlay], a widget that manages a [Stack] of entries that can be managed
///    independently.
///  * [SemanticsDebugger], a widget that visualizes the semantics for the child.
class WidgetsApp extends StatefulWidget {
/// Creates a widget that wraps a number of widgets that are commonly
/// required for an application.
///
/// The boolean arguments, [color], and [navigatorObservers] must not be null.
///
/// Most callers will want to use the [home] or [routes] parameters, or both.
/// The [home] parameter is a convenience for the following [routes] map:
///
/// dart   /// <String, WidgetBuilder>{ '/': (BuildContext context) => myWidget }   ///
///
/// It is possible to specify both [home] and [routes], but only if [routes] does
///  not contain an entry for '/'.  Conversely, if [home] is omitted, [routes]
/// must contain an entry for '/'.
///
/// If [home] or [routes] are not null, the routing implementation needs to know how
/// appropriately build [PageRoute]s. This can be achieved by supplying the
/// [pageRouteBuilder] parameter.  The [pageRouteBuilder] is used by [MaterialApp]
/// and [CupertinoApp] to create [MaterialPageRoute]s and [CupertinoPageRoute],
/// respectively.
///
/// The [builder] parameter is designed to provide the ability to wrap the visible
/// content of the app in some other widget. It is recommended that you use [home]
/// rather than [builder] if you intend to only display a single route in your app.
///
/// [WidgetsApp] is also possible to provide a custom implementation of routing via the
/// [onGenerateRoute] and [onUnknownRoute] parameters. These parameters correspond
/// to [Navigator.onGenerateRoute] and [Navigator.onUnknownRoute]. If [home], [routes],
/// and [builder] are null, or if they fail to create a requested route,
/// [onGenerateRoute] will be invoked.  If that fails, [onUnknownRoute] will be invoked.
///
/// The [pageRouteBuilder] will create a [PageRoute] that wraps newly built routes.
/// If the [builder] is non-null and the [onGenerateRoute] argument is null, then the
/// [builder] will not be provided only with the context and the child widget, whereas
/// the [pageRouteBuilder] will be provided with [RouteSettings]. If [onGenerateRoute]
/// is not provided, [navigatorKey], [onUnknownRoute], [navigatorObservers], and
/// [initialRoute] must have their default values, as they will have no effect.
///
/// The supportedLocales argument must be a list of one or more elements.
/// By default supportedLocales is [const Locale('en', 'US')].
WidgetsApp({
// can't be const because the asserts use methods on Iterable :-(
Key? key,
this.navigatorKey,
this.onGenerateRoute,
this.onGenerateInitialRoutes,
this.onUnknownRoute,
List this.navigatorObservers =
const [],
this.initialRoute,
this.pageRouteBuilder,
this.home,
Map<String, WidgetBuilder> this.routes = const <String, WidgetBuilder>{},
this.builder,
this.title = '',
this.onGenerateTitle,
this.textStyle,
required this.color,
this.locale,
this.localizationsDelegates,
this.localeListResolutionCallback,
this.localeResolutionCallback,
this.supportedLocales = const [Locale('en', 'US')],
this.showPerformanceOverlay = false,
this.checkerboardRasterCacheImages = false,
this.checkerboardOffscreenLayers = false,
this.showSemanticsDebugger = false,
this.debugShowWidgetInspector = false,
this.debugShowCheckedModeBanner = true,
this.inspectorSelectButtonBuilder,
this.shortcuts,
this.actions,
this.restorationScopeId,
})  : assert(navigatorObservers != null),
assert(routes != null),
assert(
home == null || onGenerateInitialRoutes == null,
'If onGenerateInitialRoutes is specified, the home argument will be '
'redundant.',
),
assert(
home == null || !routes.containsKey(Navigator.defaultRouteName),
'If the home property is specified, the routes table '
'cannot include an entry for "/", since it would be redundant.',
),
assert(
builder != null ||
home != null ||
routes.containsKey(Navigator.defaultRouteName) ||
onGenerateRoute != null ||
onUnknownRoute != null,
'Either the home property must be specified, '
'or the routes table must include an entry for "/", '
'or there must be on onGenerateRoute callback specified, '
'or there must be an onUnknownRoute callback specified, '
'or the builder property must be specified, '
'because otherwise there is nothing to fall back on if the '
'app is started with an intent that specifies an unknown route.',
),
assert(
(home != null ||
routes.isNotEmpty ||
onGenerateRoute != null ||
onUnknownRoute != null) ||
(builder != null &&
navigatorKey == null &&
initialRoute == null &&
navigatorObservers.isEmpty),
'If no route is provided using '
'home, routes, onGenerateRoute, or onUnknownRoute, '
'a non-null callback for the builder property must be provided, '
'and the other navigator-related properties, '
'navigatorKey, initialRoute, and navigatorObservers, '
'must have their initial values '
'(null, null, and the empty list, respectively).',
),
assert(
builder != null ||
onGenerateRoute != null ||
pageRouteBuilder != null,
'If neither builder nor onGenerateRoute are provided, the '
'pageRouteBuilder must be specified so that the default handler '
'will know what kind of PageRoute transition to build.',
),
assert(title != null),
assert(color != null),
assert(supportedLocales != null && supportedLocales.isNotEmpty),
assert(showPerformanceOverlay != null),
assert(checkerboardRasterCacheImages != null),
assert(checkerboardOffscreenLayers != null),
assert(showSemanticsDebugger != null),
assert(debugShowCheckedModeBanner != null),
assert(debugShowWidgetInspector != null),
routeInformationProvider = null,
routeInformationParser = null,
routerDelegate = null,
backButtonDispatcher = null,
super(key: key);
/// Creates a [WidgetsApp] that uses the [Router] instead of a [Navigator].
WidgetsApp.router({
Key? key,
this.routeInformationProvider,
required RouteInformationParser this.routeInformationParser,
required RouterDelegate this.routerDelegate,
BackButtonDispatcher? backButtonDispatcher,
this.builder,
this.title = '',
this.onGenerateTitle,
this.textStyle,
required this.color,
this.locale,
this.localizationsDelegates,
this.localeListResolutionCallback,
this.localeResolutionCallback,
this.supportedLocales = const [Locale('en', 'US')],
this.showPerformanceOverlay = false,
this.checkerboardRasterCacheImages = false,
this.checkerboardOffscreenLayers = false,
this.showSemanticsDebugger = false,
this.debugShowWidgetInspector = false,
this.debugShowCheckedModeBanner = true,
this.inspectorSelectButtonBuilder,
this.shortcuts,
this.actions,
this.restorationScopeId,
})  : assert(
routeInformationParser != null && routerDelegate != null,
'The routeInformationParser and routerDelegate cannot be null.',
),
assert(title != null),
assert(color != null),
assert(supportedLocales != null && supportedLocales.isNotEmpty),
assert(showPerformanceOverlay != null),
assert(checkerboardRasterCacheImages != null),
assert(checkerboardOffscreenLayers != null),
assert(showSemanticsDebugger != null),
assert(debugShowCheckedModeBanner != null),
assert(debugShowWidgetInspector != null),
navigatorObservers = null,
backButtonDispatcher =
backButtonDispatcher ?? RootBackButtonDispatcher(),
navigatorKey = null,
onGenerateRoute = null,
pageRouteBuilder = null,
home = null,
onGenerateInitialRoutes = null,
onUnknownRoute = null,
routes = null,
initialRoute = null,
super(key: key);
/// {@template flutter.widgets.widgetsApp.navigatorKey}
/// A key to use when building the [Navigator].
///
/// If a [navigatorKey] is specified, the [Navigator] can be directly
/// manipulated without first obtaining it from a [BuildContext] via
/// [Navigator.of]: from the [navigatorKey], use the [GlobalKey.currentState]
/// getter.
///
/// If this is changed, a new [Navigator] will be created, losing all the
/// application state in the process; in that case, the [navigatorObservers]
/// must also be changed, since the previous observers will be attached to the
/// previous navigator.
///
/// The [Navigator] is only built if [onGenerateRoute] is not null; if it is
/// null, [navigatorKey] must also be null.
/// {@endtemplate}
final GlobalKey? navigatorKey;
/// {@template flutter.widgets.widgetsApp.onGenerateRoute}
/// The route generator callback used when the app is navigated to a
/// named route.
///
/// If this returns null when building the routes to handle the specified
/// [initialRoute], then all the routes are discarded and
/// [Navigator.defaultRouteName] is used instead (/). See [initialRoute].
///
/// During normal app operation, the [onGenerateRoute] callback will only be
/// applied to route names pushed by the application, and so should never
/// return null.
///
/// This is used if [routes] does not contain the requested route.
///
/// The [Navigator] is only built if routes are provided (either via [home],
/// [routes], [onGenerateRoute], or [onUnknownRoute]); if they are not,
/// [builder] must not be null.
/// {@endtemplate}
///
/// If this property is not set, either the [routes] or [home] properties must
/// be set, and the [pageRouteBuilder] must also be set so that the
/// default handler will know what routes and [PageRoute]s to build.
final RouteFactory? onGenerateRoute;
/// {@template flutter.widgets.widgetsApp.onGenerateInitialRoutes}
/// The routes generator callback used for generating initial routes if
/// [initialRoute] is provided.
///
/// If this property is not set, the underlying
/// [Navigator.onGenerateInitialRoutes] will default to
/// [Navigator.defaultGenerateInitialRoutes].
/// {@endtemplate}
final InitialRouteListFactory? onGenerateInitialRoutes;
/// The [PageRoute] generator callback used when the app is navigated to a
/// named route.
///
/// This callback can be used, for example, to specify that a [MaterialPageRoute]
/// or a [CupertinoPageRoute] should be used for building page transitions.
final PageRouteFactory? pageRouteBuilder;
/// {@template flutter.widgets.widgetsApp.routeInformationParser}
/// A delegate to parse the route information from the
/// [routeInformationProvider] into a generic data type to be processed by
/// the [routerDelegate] at a later stage.
///
/// This object will be used by the underlying [Router].
///
/// The generic type T must match the generic type of the [routerDelegate].
///
/// See also:
///
///  * [Router.routeInformationParser]: which receives this object when this
///    widget builds the [Router].
/// {@endtemplate}
final RouteInformationParser? routeInformationParser;
/// {@template flutter.widgets.widgetsApp.routerDelegate}
/// A delegate that configures a widget, typically a [Navigator], with
/// parsed result from the [routeInformationParser].
///
/// This object will be used by the underlying [Router].
///
/// The generic type T must match the generic type of the
/// [routeInformationParser].
///
/// See also:
///
///  * [Router.routerDelegate]: which receives this object when this widget
///    builds the [Router].
/// {@endtemplate}
final RouterDelegate? routerDelegate;
/// {@template flutter.widgets.widgetsApp.backButtonDispatcher}
/// A delegate that decide whether to handle the Android back button intent.
///
/// This object will be used by the underlying [Router].
///
/// If this is not provided, the widgets app will create a
/// [RootBackButtonDispatcher] by default.
///
/// See also:
///
///  * [Router.backButtonDispatcher]: which receives this object when this
///    widget builds the [Router].
/// {@endtemplate}
final BackButtonDispatcher? backButtonDispatcher;
/// {@template flutter.widgets.widgetsApp.routeInformationProvider}
/// A object that provides route information through the
/// [RouteInformationProvider.value] and notifies its listener when its value
/// changes.
///
/// This object will be used by the underlying [Router].
///
/// If this is not provided, the widgets app will create a
/// [PlatformRouteInformationProvider] with initial route name equal to the
/// [dart:ui.PlatformDispatcher.defaultRouteName] by default.
///
/// See also:
///
///  * [Router.routeInformationProvider]: which receives this object when this
///    widget builds the [Router].
/// {@endtemplate}
final RouteInformationProvider? routeInformationProvider;
/// {@template flutter.widgets.widgetsApp.home}
/// The widget for the default route of the app ([Navigator.defaultRouteName],
/// which is /).
///
/// This is the route that is displayed first when the application is started
/// normally, unless [initialRoute] is specified. It's also the route that's
/// displayed if the [initialRoute] can't be displayed.
///
/// To be able to directly call [Theme.of], [MediaQuery.of], etc, in the code
/// that sets the [home] argument in the constructor, you can use a [Builder]
/// widget to get a [BuildContext].
///
/// If [home] is specified, then [routes] must not include an entry for /,
/// as [home] takes its place.
///
/// The [Navigator] is only built if routes are provided (either via [home],
/// [routes], [onGenerateRoute], or [onUnknownRoute]); if they are not,
/// [builder] must not be null.
///
/// The difference between using [home] and using [builder] is that the [home]
/// subtree is inserted into the application below a [Navigator] (and thus
/// below an [Overlay], which [Navigator] uses). With [home], therefore,
/// dialog boxes will work automatically, the [routes] table will be used, and
/// APIs such as [Navigator.push] and [Navigator.pop] will work as expected.
/// In contrast, the widget returned from [builder] is inserted above the
/// app's [Navigator] (if any).
/// {@endtemplate}
///
/// If this property is set, the [pageRouteBuilder] property must also be set
/// so that the default route handler will know what kind of [PageRoute]s to
/// build.
final Widget? home;
/// 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 [PageRoute] specified by
/// [pageRouteBuilder] to perform an appropriate transition, including [Hero]
/// animations, to the new route.
///
/// {@template flutter.widgets.widgetsApp.routes}
/// If the app only has one page, then you can specify it using [home] instead.
///
/// If [home] is specified, then it implies an entry in this table for the
/// [Navigator.defaultRouteName] route (/), and it is an error to
/// redundantly provide such a route in the [routes] table.
///
/// If a route is requested that is not specified in this table (or by
/// [home]), then the [onGenerateRoute] callback is called to build the page
/// instead.
///
/// The [Navigator] is only built if routes are provided (either via [home],
/// [routes], [onGenerateRoute], or [onUnknownRoute]); if they are not,
/// [builder] must not be null.
/// {@endtemplate}
///
/// If the routes map is not empty, the [pageRouteBuilder] property must be set
/// so that the default route handler will know what kind of [PageRoute]s to
/// build.
final Map<String, WidgetBuilder>? routes;
/// {@template flutter.widgets.widgetsApp.onUnknownRoute}
/// Called when [onGenerateRoute] fails to generate a route, except for the
/// [initialRoute].
///
/// This callback is typically used for error handling. For example, this
/// callback might always generate a "not found" page that describes the route
/// that wasn't found.
///
/// Unknown routes can arise either from errors in the app or from external
/// requests to push routes, such as from Android intents.
///
/// The [Navigator] is only built if routes are provided (either via [home],
/// [routes], [onGenerateRoute], or [onUnknownRoute]); if they are not,
/// [builder] must not be null.
/// {@endtemplate}
final RouteFactory? onUnknownRoute;
/// {@template flutter.widgets.widgetsApp.initialRoute}
/// The name of the first route to show, if a [Navigator] is built.
///
/// Defaults to [dart:ui.PlatformDispatcher.defaultRouteName], which may be
/// overridden by the code that launched the application.
///
/// If the route name starts with a slash, then it is treated as a "deep link",
/// and before this route is pushed, the routes leading to this one are pushed
/// also. For example, if the route was /a/b/c, then the app would start
/// with the four routes /, /a, /a/b, and /a/b/c loaded, in that order.
/// Even if the route was just /a, the app would start with / and /a
/// loaded. You can use the [onGenerateInitialRoutes] property to override
/// this behavior.
///
/// Intermediate routes aren't required to exist. In the example above, /a
/// and /a/b could be skipped if they have no matching route. But /a/b/c is
/// required to have a route, else [initialRoute] is ignored and
/// [Navigator.defaultRouteName] is used instead (/). This can happen if the
/// app is started with an intent that specifies a non-existent route.
///
/// The [Navigator] is only built if routes are provided (either via [home],
/// [routes], [onGenerateRoute], or [onUnknownRoute]); if they are not,
/// [initialRoute] must be null and [builder] must not be null.
///
/// See also:
///
///  * [Navigator.initialRoute], which is used to implement this property.
///  * [Navigator.push], for pushing additional routes.
///  * [Navigator.pop], for removing a route from the stack.
///
/// {@endtemplate}
final String? initialRoute;
/// {@template flutter.widgets.widgetsApp.navigatorObservers}
/// The list of observers for the [Navigator] created for this app.
///
/// This list must be replaced by a list of newly-created observers if the
/// [navigatorKey] is changed.
///
/// The [Navigator] is only built if routes are provided (either via [home],
/// [routes], [onGenerateRoute], or [onUnknownRoute]); if they are not,
/// [navigatorObservers] must be the empty list and [builder] must not be null.
/// {@endtemplate}
final List? navigatorObservers;
/// {@template flutter.widgets.widgetsApp.builder}
/// A builder for inserting widgets above the [Navigator] or - when the
/// [WidgetsApp.router] constructor is used - above the [Router] but below the
/// other widgets created by the [WidgetsApp] widget, or for replacing the
/// [Navigator]/[Router] entirely.
///
/// For example, from the [BuildContext] passed to this method, the
/// [Directionality], [Localizations], [DefaultTextStyle], [MediaQuery], etc,
/// are all available. They can also be overridden in a way that impacts all
/// the routes in the [Navigator] or [Router].
///
/// This is rarely useful, but can be used in applications that wish to
/// override those defaults, e.g. to force the application into right-to-left
/// mode despite being in English, or to override the [MediaQuery] metrics
/// (e.g. to leave a gap for advertisements shown by a plugin from OEM code).
///
/// For specifically overriding the [title] with a value based on the
/// [Localizations], consider [onGenerateTitle] instead.
///
/// The [builder] callback is passed two arguments, the [BuildContext] (as
/// context) and a [Navigator] or [Router] widget (as child).
///
/// If no routes are provided to the regular [WidgetsApp] constructor using
/// [home], [routes], [onGenerateRoute], or [onUnknownRoute], the child will
/// be null, and it is the responsibility of the [builder] to provide the
/// application's routing machinery.
///
/// If routes are provided to the regular [WidgetsApp] constructor using one
/// or more of those properties or if the [WidgetsApp.router] constructor is
/// used, then child is not null, and the returned value should include the
/// child in the widget subtree; if it does not, then the application will
/// have no [Navigator] or [Router] and the routing related properties (i.e.
/// [navigatorKey], [home], [routes], [onGenerateRoute], [onUnknownRoute],
/// [initialRoute], [navigatorObservers], [routeInformationProvider],
/// [backButtonDispatcher], [routerDelegate], and [routeInformationParser])
/// are ignored.
///
/// If [builder] is null, it is as if a builder was specified that returned
/// the child directly. If it is null, routes must be provided using one of
/// the other properties listed above.
///
/// Unless a [Navigator] is provided, either implicitly from [builder] being
/// null, or by a [builder] including its child argument, or by a [builder]
/// explicitly providing a [Navigator] of its own, or by the [routerDelegate]
/// building one, widgets and APIs such as [Hero], [Navigator.push] and
/// [Navigator.pop], will not function.
/// {@endtemplate}
final TransitionBuilder? builder;
/// {@template flutter.widgets.widgetsApp.title}
/// A one-line description used by the device to identify the app for the user.
///
/// On Android the titles appear above the task manager's app snapshots which are
/// displayed when the user presses the "recent apps" button. On iOS this
/// value cannot be used. CFBundleDisplayName from the app's Info.plist is
/// referred to instead whenever present, CFBundleName otherwise.
/// On the web it is used as the page title, which shows up in the browser's list of open tabs.
///
/// To provide a localized title instead, use [onGenerateTitle].
/// {@endtemplate}
final String title;
/// {@template flutter.widgets.widgetsApp.onGenerateTitle}
/// If non-null this callback function is called to produce the app's
/// title string, otherwise [title] is used.
///
/// The [onGenerateTitle] context parameter includes the [WidgetsApp]'s
/// [Localizations] widget so that this callback can be used to produce a
/// localized title.
///
/// This callback function must not return null.
///
/// The [onGenerateTitle] callback is called each time the [WidgetsApp]
/// rebuilds.
/// {@endtemplate}
final GenerateAppTitle? onGenerateTitle;
/// The default text style for [Text] in the application.
final TextStyle? textStyle;
/// {@template flutter.widgets.widgetsApp.color}
/// The primary color to use for the application in the operating system
/// interface.
///
/// For example, on Android this is the color used for the application in the
/// application switcher.
/// {@endtemplate}
final Color color;
/// {@template flutter.widgets.widgetsApp.locale}
/// The initial locale for this app's [Localizations] widget is based
/// on this value.
///
/// If the 'locale' is null then the system's locale value is used.
///
/// The value of [Localizations.locale] will equal this locale if
/// it matches one of the [supportedLocales]. Otherwise it will be
/// the first element of [supportedLocales].
/// {@endtemplate}
///
/// See also:
///
///  * [localeResolutionCallback], which can override the default
///    [supportedLocales] matching algorithm.
///  * [localizationsDelegates], which collectively define all of the localized
///    resources used by this app.
final Locale? locale;
/// {@template flutter.widgets.widgetsApp.localizationsDelegates}
/// The delegates for this app's [Localizations] widget.
///
/// The delegates collectively define all of the localized resources
/// for this application's [Localizations] widget.
/// {@endtemplate}
final Iterable<LocalizationsDelegate>? localizationsDelegates;
/// {@template flutter.widgets.widgetsApp.localeListResolutionCallback}
/// This callback is responsible for choosing the app's locale
/// when the app is started, and when the user changes the
/// device's locale.
///
/// When a [localeListResolutionCallback] is provided, Flutter will first
/// attempt to resolve the locale with the provided
/// [localeListResolutionCallback]. If the callback or result is null, it will
/// fallback to trying the [localeResolutionCallback]. If both
/// [localeResolutionCallback] and [localeListResolutionCallback] are left
/// null or fail to resolve (return null), the a basic fallback algorithm will
/// be used.
///
/// The priority of each available fallback is:
///
///  1. [localeListResolutionCallback] is attempted first.
///  1. [localeResolutionCallback] is attempted second.
///  1. Flutter's basic resolution algorithm, as described in
///     [supportedLocales], is attempted last.
///
/// Properly localized projects should provide a more advanced algorithm than
/// the basic method from [supportedLocales], as it does not implement a
/// complete algorithm (such as the one defined in
/// Unicode TR35)
/// and is optimized for speed at the detriment of some uncommon edge-cases.
/// {@endtemplate}
///
/// This callback considers the entire list of preferred locales.
///
/// This algorithm should be able to handle a null or empty list of preferred locales,
/// which indicates Flutter has not yet received locale information from the platform.
///
/// See also:
///
///  * [MaterialApp.localeListResolutionCallback], which sets the callback of the
///    [WidgetsApp] it creates.
final LocaleListResolutionCallback? localeListResolutionCallback;
/// {@macro flutter.widgets.widgetsApp.localeListResolutionCallback}
///
/// This callback considers only the default locale, which is the first locale
/// in the preferred locales list. It is preferred to set [localeListResolutionCallback]
/// over [localeResolutionCallback] as it provides the full preferred locales list.
///
/// This algorithm should be able to handle a null locale, which indicates
/// Flutter has not yet received locale information from the platform.
///
/// See also:
///
///  * [MaterialApp.localeResolutionCallback], which sets the callback of the
///    [WidgetsApp] it creates.
final LocaleResolutionCallback? localeResolutionCallback;
/// {@template flutter.widgets.widgetsApp.supportedLocales}
/// The list of locales that this app has been localized for.
///
/// By default only the American English locale is supported. Apps should
/// configure this list to match the locales they support.
///
/// This list must not null. Its default value is just
/// [const Locale('en', 'US')].
///
/// The order of the list matters. The default locale resolution algorithm,
/// basicLocaleListResolution, attempts to match by the following priority:
///
///  1. [Locale.languageCode], [Locale.scriptCode], and [Locale.countryCode]
///  2. [Locale.languageCode] and [Locale.scriptCode] only
///  3. [Locale.languageCode] and [Locale.countryCode] only
///  4. [Locale.languageCode] only
///  5. [Locale.countryCode] only when all preferred locales fail to match
///  6. Returns the first element of [supportedLocales] as a fallback
///
/// When more than one supported locale matches one of these criteria, only
/// the first matching locale is returned.
///
/// The default locale resolution algorithm can be overridden by providing a
/// value for [localeListResolutionCallback]. The provided
/// basicLocaleListResolution is optimized for speed and does not implement
/// a full algorithm (such as the one defined in
/// Unicode TR35) that
/// takes distances between languages into account.
///
/// When supporting languages with more than one script, it is recommended
/// to specify the [Locale.scriptCode] explicitly. Locales may also be defined without
/// [Locale.countryCode] to specify a generic fallback for a particular script.
///
/// A fully supported language with multiple scripts should define a generic language-only
/// locale (e.g. 'zh'), language+script only locales (e.g. 'zh_Hans' and 'zh_Hant'),
/// and any language+script+country locales (e.g. 'zh_Hans_CN'). Fully defining all of
/// these locales as supported is not strictly required but allows for proper locale resolution in
/// the most number of cases. These locales can be specified with the [Locale.fromSubtags]
/// constructor:
///
/// dart   /// // Full Chinese support for CN, TW, and HK   /// supportedLocales: [   ///   const Locale.fromSubtags(languageCode: 'zh'), // generic Chinese 'zh'   ///   const Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hans'), // generic simplified Chinese 'zh_Hans'   ///   const Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hant'), // generic traditional Chinese 'zh_Hant'   ///   const Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hans', countryCode: 'CN'), // 'zh_Hans_CN'   ///   const Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hant', countryCode: 'TW'), // 'zh_Hant_TW'   ///   const Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hant', countryCode: 'HK'), // 'zh_Hant_HK'   /// ],   ///
///
/// Omitting some these fallbacks may result in improperly resolved
/// edge-cases, for example, a simplified Chinese user in Taiwan ('zh_Hans_TW')
/// may resolve to traditional Chinese if 'zh_Hans' and 'zh_Hans_CN' are
/// omitted.
/// {@endtemplate}
///
/// See also:
///
///  * [MaterialApp.supportedLocales], which sets the supportedLocales
///    of the [WidgetsApp] it creates.
///  * [localeResolutionCallback], an app callback that resolves the app's locale
///    when the device's locale changes.
///  * [localizationsDelegates], which collectively define all of the localized
///    resources used by this app.
final Iterable supportedLocales;
/// Turns on a performance overlay.
///
/// See also:
///
///  * https://flutter.dev/debugging/#performanceoverlay
final bool showPerformanceOverlay;
/// Checkerboards raster cache images.
///
/// See [PerformanceOverlay.checkerboardRasterCacheImages].
final bool checkerboardRasterCacheImages;
/// Checkerboards layers rendered to offscreen bitmaps.
///
/// See [PerformanceOverlay.checkerboardOffscreenLayers].
final bool checkerboardOffscreenLayers;
/// Turns on an overlay that shows the accessibility information
/// reported by the framework.
final bool showSemanticsDebugger;
/// Turns on an overlay that enables inspecting the widget tree.
///
/// The inspector is only available in checked mode as it depends on
/// [RenderObject.debugDescribeChildren] which should not be called outside of
/// checked mode.
final bool debugShowWidgetInspector;
/// Builds the widget the [WidgetInspector] uses to switch between view and
/// inspect modes.
///
/// This lets [MaterialApp] to use a material button to toggle the inspector
/// select mode without requiring [WidgetInspector] to depend on the
/// material package.
final InspectorSelectButtonBuilder? inspectorSelectButtonBuilder;
/// {@template flutter.widgets.widgetsApp.debugShowCheckedModeBanner}
/// Turns on a little "DEBUG" banner in checked mode to indicate
/// that the app is in checked mode. This is on by default (in
/// checked mode), to turn it off, set the constructor argument to
/// false. In release mode this has no effect.
///
/// To get this banner in your application if you're not using
/// WidgetsApp, include a [CheckedModeBanner] widget in your app.
///
/// This banner is intended to deter people from complaining that your
/// app is slow when it's in checked mode. In checked mode, Flutter
/// enables a large number of expensive diagnostics to aid in
/// development, and so performance in checked mode is not
/// representative of what will happen in release mode.
/// {@endtemplate}
final bool debugShowCheckedModeBanner;
/// {@template flutter.widgets.widgetsApp.shortcuts}
/// The default map of keyboard shortcuts to intents for the application.
///
/// By default, this is set to [WidgetsApp.defaultShortcuts].
///
/// Passing this will not replace [DefaultTextEditingShortcuts]. These can be
/// overridden by using a [Shortcuts] widget lower in the widget tree.
/// {@endtemplate}
///
/// {@tool snippet}
/// This example shows how to add a single shortcut for
/// [LogicalKeyboardKey.select] to the default shortcuts without needing to
/// add your own [Shortcuts] widget.
///
/// Alternatively, you could insert a [Shortcuts] widget with just the mapping
/// you want to add between the [WidgetsApp] and its child and get the same
/// effect.
///
/// dart   /// Widget build(BuildContext context) {   ///   return WidgetsApp(   ///     shortcuts: <LogicalKeySet, Intent>{   ///       ... WidgetsApp.defaultShortcuts,   ///       LogicalKeySet(LogicalKeyboardKey.select): const ActivateIntent(),   ///     },   ///     color: const Color(0xFFFF0000),   ///     builder: (BuildContext context, Widget? child) {   ///       return const Placeholder();   ///     },   ///   );   /// }   ///
/// {@end-tool}
///
/// {@template flutter.widgets.widgetsApp.shortcuts.seeAlso}
/// See also:
///
///  * [LogicalKeySet], a set of [LogicalKeyboardKey]s that make up the keys
///    for this map.
///  * The [Shortcuts] widget, which defines a keyboard mapping.
///  * The [Actions] widget, which defines the mapping from intent to action.
///  * The [Intent] and [Action] classes, which allow definition of new
///    actions.
/// {@endtemplate}
final Map<LogicalKeySet, Intent>? shortcuts;
/// {@template flutter.widgets.widgetsApp.actions}
/// The default map of intent keys to actions for the application.
///
/// By default, this is the output of [WidgetsApp.defaultActions], called with
/// [defaultTargetPlatform]. Specifying [actions] for an app overrides the
/// default, so if you wish to modify the default [actions], you can call
/// [WidgetsApp.defaultActions] and modify the resulting map, passing it as
/// the [actions] for this app. You may also add to the bindings, or override
/// specific bindings for a widget subtree, by adding your own [Actions]
/// widget.
///
/// Passing this will not replace [DefaultTextEditingActions]. These can be
/// overridden by placing an [Actions] widget lower in the widget tree.
/// {@endtemplate}
///
/// {@tool snippet}
/// This example shows how to add a single action handling an
/// [ActivateAction] to the default actions without needing to
/// add your own [Actions] widget.
///
/// Alternatively, you could insert a [Actions] widget with just the mapping
/// you want to add between the [WidgetsApp] and its child and get the same
/// effect.
///
/// dart   /// Widget build(BuildContext context) {   ///   return WidgetsApp(   ///     actions: <Type, Action<Intent>>{   ///       ... WidgetsApp.defaultActions,   ///       ActivateAction: CallbackAction<Intent>(   ///         onInvoke: (Intent intent) {   ///           // Do something here...   ///           return null;   ///         },   ///       ),   ///     },   ///     color: const Color(0xFFFF0000),   ///     builder: (BuildContext context, Widget? child) {   ///       return const Placeholder();   ///     },   ///   );   /// }   ///
/// {@end-tool}
///
/// {@template flutter.widgets.widgetsApp.actions.seeAlso}
/// See also:
///
///  * The [shortcuts] parameter, which defines the default set of shortcuts
///    for the application.
///  * The [Shortcuts] widget, which defines a keyboard mapping.
///  * The [Actions] widget, which defines the mapping from intent to action.
///  * The [Intent] and [Action] classes, which allow definition of new
///    actions.
/// {@endtemplate}
final Map<Type, Action>? actions;
/// {@template flutter.widgets.widgetsApp.restorationScopeId}
/// The identifier to use for state restoration of this app.
///
/// Providing a restoration ID inserts a [RootRestorationScope] into the
/// widget hierarchy, which enables state restoration for descendant widgets.
///
/// Providing a restoration ID also enables the [Navigator] built by the
/// [WidgetsApp] to restore its state (i.e. to restore the history stack of
/// active [Route]s). See the documentation on [Navigator] for more details
/// around state restoration of [Route]s.
///
/// See also:
///
///  * [RestorationManager], which explains how state restoration works in
///    Flutter.
/// {@endtemplate}
final String? restorationScopeId;
/// If true, forces the performance overlay to be visible in all instances.
///
/// Used by the showPerformanceOverlay observatory extension.
static bool showPerformanceOverlayOverride = false;
/// If true, forces the widget inspector to be visible.
///
/// Used by the debugShowWidgetInspector debugging extension.
///
/// The inspector allows you to select a location on your device or emulator
/// and view what widgets and render objects associated with it. An outline of
/// the selected widget and some summary information is shown on device and
/// more detailed information is shown in the IDE or Observatory.
static bool debugShowWidgetInspectorOverride = false;
/// If false, prevents the debug banner from being visible.
///
/// Used by the debugAllowBanner observatory extension.
///
/// This is how flutter run turns off the banner when you take a screen shot
/// with "s".
static bool debugAllowBannerOverride = true;
static final Map<LogicalKeySet, Intent> _defaultShortcuts =
<LogicalKeySet, Intent>{
// Activation
LogicalKeySet(LogicalKeyboardKey.enter): const ActivateIntent(),
LogicalKeySet(LogicalKeyboardKey.space): const ActivateIntent(),
LogicalKeySet(LogicalKeyboardKey.gameButtonA): const ActivateIntent(),
// Dismissal
LogicalKeySet(LogicalKeyboardKey.escape): const DismissIntent(),

// Keyboard traversal.
LogicalKeySet(LogicalKeyboardKey.tab): const NextFocusIntent(),
LogicalKeySet(LogicalKeyboardKey.shift, LogicalKeyboardKey.tab):
    const PreviousFocusIntent(),
LogicalKeySet(LogicalKeyboardKey.arrowLeft):
    const DirectionalFocusIntent(TraversalDirection.left),
LogicalKeySet(LogicalKeyboardKey.arrowRight):
    const DirectionalFocusIntent(TraversalDirection.right),
LogicalKeySet(LogicalKeyboardKey.arrowDown):
    const DirectionalFocusIntent(TraversalDirection.down),
LogicalKeySet(LogicalKeyboardKey.arrowUp):
    const DirectionalFocusIntent(TraversalDirection.up),

// Scrolling
LogicalKeySet(LogicalKeyboardKey.control, LogicalKeyboardKey.arrowUp):
    const ScrollIntent(direction: AxisDirection.up),
LogicalKeySet(LogicalKeyboardKey.control, LogicalKeyboardKey.arrowDown):
    const ScrollIntent(direction: AxisDirection.down),
LogicalKeySet(LogicalKeyboardKey.control, LogicalKeyboardKey.arrowLeft):
    const ScrollIntent(direction: AxisDirection.left),
LogicalKeySet(LogicalKeyboardKey.control, LogicalKeyboardKey.arrowRight):
    const ScrollIntent(direction: AxisDirection.right),
LogicalKeySet(LogicalKeyboardKey.pageUp): const ScrollIntent(
    direction: AxisDirection.up, type: ScrollIncrementType.page),
LogicalKeySet(LogicalKeyboardKey.pageDown): const ScrollIntent(
    direction: AxisDirection.down, type: ScrollIncrementType.page),

};
// Default shortcuts for the web platform.
static final Map<LogicalKeySet, Intent> _defaultWebShortcuts =
<LogicalKeySet, Intent>{
// Activation
LogicalKeySet(LogicalKeyboardKey.space): const PrioritizedIntents(
orderedIntents: [
ActivateIntent(),
ScrollIntent(
direction: AxisDirection.down, type: ScrollIncrementType.page),
],
),
// On the web, enter activates buttons, but not other controls.
LogicalKeySet(LogicalKeyboardKey.enter): const ButtonActivateIntent(),
// Dismissal
LogicalKeySet(LogicalKeyboardKey.escape): const DismissIntent(),

// Keyboard traversal.
LogicalKeySet(LogicalKeyboardKey.tab): const NextFocusIntent(),
LogicalKeySet(LogicalKeyboardKey.shift, LogicalKeyboardKey.tab):
    const PreviousFocusIntent(),

// Scrolling
LogicalKeySet(LogicalKeyboardKey.arrowUp):
    const ScrollIntent(direction: AxisDirection.up),
LogicalKeySet(LogicalKeyboardKey.arrowDown):
    const ScrollIntent(direction: AxisDirection.down),
LogicalKeySet(LogicalKeyboardKey.arrowLeft):
    const ScrollIntent(direction: AxisDirection.left),
LogicalKeySet(LogicalKeyboardKey.arrowRight):
    const ScrollIntent(direction: AxisDirection.right),
LogicalKeySet(LogicalKeyboardKey.pageUp): const ScrollIntent(
    direction: AxisDirection.up, type: ScrollIncrementType.page),
LogicalKeySet(LogicalKeyboardKey.pageDown): const ScrollIntent(
    direction: AxisDirection.down, type: ScrollIncrementType.page),

};
// Default shortcuts for the macOS platform.
static final Map<LogicalKeySet, Intent> _defaultAppleOsShortcuts =
<LogicalKeySet, Intent>{
// Activation
LogicalKeySet(LogicalKeyboardKey.enter): const ActivateIntent(),
LogicalKeySet(LogicalKeyboardKey.space): const ActivateIntent(),
// Dismissal
LogicalKeySet(LogicalKeyboardKey.escape): const DismissIntent(),

// Keyboard traversal
LogicalKeySet(LogicalKeyboardKey.tab): const NextFocusIntent(),
LogicalKeySet(LogicalKeyboardKey.shift, LogicalKeyboardKey.tab):
    const PreviousFocusIntent(),
LogicalKeySet(LogicalKeyboardKey.arrowLeft):
    const DirectionalFocusIntent(TraversalDirection.left),
LogicalKeySet(LogicalKeyboardKey.arrowRight):
    const DirectionalFocusIntent(TraversalDirection.right),
LogicalKeySet(LogicalKeyboardKey.arrowDown):
    const DirectionalFocusIntent(TraversalDirection.down),
LogicalKeySet(LogicalKeyboardKey.arrowUp):
    const DirectionalFocusIntent(TraversalDirection.up),

// Scrolling
LogicalKeySet(LogicalKeyboardKey.meta, LogicalKeyboardKey.arrowUp):
    const ScrollIntent(direction: AxisDirection.up),
LogicalKeySet(LogicalKeyboardKey.meta, LogicalKeyboardKey.arrowDown):
    const ScrollIntent(direction: AxisDirection.down),
LogicalKeySet(LogicalKeyboardKey.meta, LogicalKeyboardKey.arrowLeft):
    const ScrollIntent(direction: AxisDirection.left),
LogicalKeySet(LogicalKeyboardKey.meta, LogicalKeyboardKey.arrowRight):
    const ScrollIntent(direction: AxisDirection.right),
LogicalKeySet(LogicalKeyboardKey.pageUp): const ScrollIntent(
    direction: AxisDirection.up, type: ScrollIncrementType.page),
LogicalKeySet(LogicalKeyboardKey.pageDown): const ScrollIntent(
    direction: AxisDirection.down, type: ScrollIncrementType.page),

};
/// Generates the default shortcut key bindings based on the
/// [defaultTargetPlatform].
///
/// Used by [WidgetsApp] to assign a default value to [WidgetsApp.shortcuts].
static Map<LogicalKeySet, Intent> get defaultShortcuts {
if (kIsWeb) {
return _defaultWebShortcuts;
}
switch (defaultTargetPlatform) {
  case TargetPlatform.android:
  case TargetPlatform.fuchsia:
  case TargetPlatform.linux:
  case TargetPlatform.windows:
    return _defaultShortcuts;
  case TargetPlatform.iOS:
  case TargetPlatform.macOS:
    return _defaultAppleOsShortcuts;
}

}
/// The default value of [WidgetsApp.actions].
static Map<Type, Action> defaultActions = <Type, Action>{
DoNothingIntent: DoNothingAction(),
DoNothingAndStopPropagationIntent: DoNothingAction(consumesKey: false),
RequestFocusIntent: RequestFocusAction(),
NextFocusIntent: NextFocusAction(),
PreviousFocusIntent: PreviousFocusAction(),
DirectionalFocusIntent: DirectionalFocusAction(),
ScrollIntent: ScrollAction(),
PrioritizedIntents: PrioritizedAction(),
};
@override
_WidgetsAppState createState() => _WidgetsAppState();
}
class _WidgetsAppState extends State with WidgetsBindingObserver {
// STATE LIFECYCLE
// If window.defaultRouteName isn't '/', we should assume it was set
// intentionally via setInitialRoute, and should override whatever is in
// [widget.initialRoute].
String get _initialRouteName => WidgetsBinding
.instance!.window.defaultRouteName !=
Navigator.defaultRouteName
? WidgetsBinding.instance!.window.defaultRouteName
: widget.initialRoute ?? WidgetsBinding.instance!.window.defaultRouteName;
@override
void initState() {
super.initState();
_updateRouting();
_locale = _resolveLocales(
WidgetsBinding.instance!.window.locales, widget.supportedLocales);
WidgetsBinding.instance!.addObserver(this);
}
@override
void didUpdateWidget(WidgetsApp oldWidget) {
super.didUpdateWidget(oldWidget);
_updateRouting(oldWidget: oldWidget);
}
@override
void dispose() {
WidgetsBinding.instance!.removeObserver(this);
_defaultRouteInformationProvider?.dispose();
super.dispose();
}
void _updateRouting({WidgetsApp? oldWidget}) {
if (_usesRouter) {
assert(!_usesNavigator);
_navigator = null;
if (oldWidget == null ||
oldWidget.routeInformationProvider !=
widget.routeInformationProvider) {
_defaultRouteInformationProvider?.dispose();
_defaultRouteInformationProvider = null;
if (widget.routeInformationProvider == null) {
_defaultRouteInformationProvider = PlatformRouteInformationProvider(
initialRouteInformation: RouteInformation(
location: _initialRouteName,
),
);
}
}
} else if (_usesNavigator) {
assert(!_usesRouter);
_defaultRouteInformationProvider?.dispose();
_defaultRouteInformationProvider = null;
if (oldWidget == null || widget.navigatorKey != oldWidget.navigatorKey) {
_navigator =
widget.navigatorKey ?? GlobalObjectKey(this);
}
assert(_navigator != null);
} else {
assert(widget.builder != null);
assert(!_usesRouter);
assert(!_usesNavigator);
_navigator = null;
_defaultRouteInformationProvider?.dispose();
_defaultRouteInformationProvider = null;
}
// If we use a navigator, we have a navigator key.
assert(_usesNavigator == (_navigator != null));
}
bool get _usesRouter => widget.routerDelegate != null;
bool get _usesNavigator =>
widget.home != null ||
widget.routes?.isNotEmpty == true ||
widget.onGenerateRoute != null ||
widget.onUnknownRoute != null;
// ROUTER
RouteInformationProvider? get _effectiveRouteInformationProvider =>
widget.routeInformationProvider ?? _defaultRouteInformationProvider;
PlatformRouteInformationProvider? _defaultRouteInformationProvider;
// NAVIGATOR
GlobalKey? _navigator;
Route? _onGenerateRoute(RouteSettings settings) {
final String? name = settings.name;
final WidgetBuilder? pageContentBuilder =
name == Navigator.defaultRouteName && widget.home != null
? (BuildContext context) => widget.home!
: widget.routes![name];
if (pageContentBuilder != null) {
  assert(
    widget.pageRouteBuilder != null,
    'The default onGenerateRoute handler for WidgetsApp must have a '
    'pageRouteBuilder set if the home or routes properties are set.',
  );
  final Route<dynamic> route = widget.pageRouteBuilder!<dynamic>(
    settings,
    pageContentBuilder,
  );
  assert(route != null,
      'The pageRouteBuilder for WidgetsApp must return a valid non-null Route.');
  return route;
}
if (widget.onGenerateRoute != null)
  return widget.onGenerateRoute!(settings);
return null;

}
Route _onUnknownRoute(RouteSettings settings) {
assert(() {
if (widget.onUnknownRoute == null) {
throw FlutterError(
'Could not find a generator for route $settings in the $runtimeType.\n'
'Make sure your root app widget has provided a way to generate \n'
'this route.\n'
'Generators for routes are searched for in the following order:\n'
' 1. For the "/" route, the "home" property, if non-null, is used.\n'
' 2. Otherwise, the "routes" table is used, if it has an entry for '
'the route.\n'
' 3. Otherwise, onGenerateRoute is called. It should return a '
'non-null value for any valid route not handled by "home" and "routes".\n'
' 4. Finally if all else fails onUnknownRoute is called.\n'
'Unfortunately, onUnknownRoute was not set.',
);
}
return true;
}());
final Route? result = widget.onUnknownRoute!(settings);
assert(() {
if (result == null) {
throw FlutterError(
'The onUnknownRoute callback returned null.\n'
'When the $runtimeType requested the route $settings from its '
'onUnknownRoute callback, the callback returned null. Such callbacks '
'must never return null.',
);
}
return true;
}());
return result!;
}
// On Android: the user has pressed the back button.
@override
Future didPopRoute() async {
assert(mounted);
// The back button dispatcher should handle the pop route if we use a
// router.
if (_usesRouter) return false;
final NavigatorState? navigator = _navigator?.currentState;
if (navigator == null) return false;
return navigator.maybePop();

}
@override
Future didPushRoute(String route) async {
assert(mounted);
// The route name provider should handle the push route if we uses a
// router.
if (_usesRouter) return false;
final NavigatorState? navigator = _navigator?.currentState;
if (navigator == null) return false;
navigator.pushNamed(route);
return true;

}
// LOCALIZATION
/// This is the resolved locale, and is one of the supportedLocales.
Locale? _locale;
Locale _resolveLocales(
List? preferredLocales, Iterable supportedLocales) {
// Attempt to use localeListResolutionCallback.
if (widget.localeListResolutionCallback != null) {
final Locale? locale = widget.localeListResolutionCallback!(
preferredLocales, widget.supportedLocales);
if (locale != null) return locale;
}
// localeListResolutionCallback failed, falling back to localeResolutionCallback.
if (widget.localeResolutionCallback != null) {
final Locale? locale = widget.localeResolutionCallback!(
preferredLocales != null && preferredLocales.isNotEmpty
? preferredLocales.first
: null,
widget.supportedLocales,
);
if (locale != null) return locale;
}
// Both callbacks failed, falling back to default algorithm.
return basicLocaleListResolution(preferredLocales, supportedLocales);
}
/// The default locale resolution algorithm.
///
/// Custom resolution algorithms can be provided through
/// [WidgetsApp.localeListResolutionCallback] or
/// [WidgetsApp.localeResolutionCallback].
///
/// When no custom locale resolution algorithms are provided or if both fail
/// to resolve, Flutter will default to calling this algorithm.
///
/// This algorithm prioritizes speed at the cost of slightly less appropriate
/// resolutions for edge cases.
///
/// This algorithm will resolve to the earliest preferred locale that
/// matches the most fields, prioritizing in the order of perfect match,
/// languageCode+countryCode, languageCode+scriptCode, languageCode-only.
///
/// In the case where a locale is matched by languageCode-only and is not the
/// default (first) locale, the next preferred locale with a
/// perfect match can supersede the languageCode-only match if it exists.
///
/// When a preferredLocale matches more than one supported locale, it will
/// resolve to the first matching locale listed in the supportedLocales.
///
/// When all preferred locales have been exhausted without a match, the first
/// countryCode only match will be returned.
///
/// When no match at all is found, the first (default) locale in
/// [supportedLocales] will be returned.
///
/// To summarize, the main matching priority is:
///
///  1. [Locale.languageCode], [Locale.scriptCode], and [Locale.countryCode]
///  1. [Locale.languageCode] and [Locale.scriptCode] only
///  1. [Locale.languageCode] and [Locale.countryCode] only
///  1. [Locale.languageCode] only (with caveats, see above)
///  1. [Locale.countryCode] only when all [preferredLocales] fail to match
///  1. Returns the first element of [supportedLocales] as a fallback
///
/// This algorithm does not take language distance (how similar languages are to each other)
/// into account, and will not handle edge cases such as resolving de to fr rather than zh
/// when de is not supported and zh is listed before fr (German is closer to French
/// than Chinese).
static Locale basicLocaleListResolution(
List? preferredLocales, Iterable supportedLocales) {
// preferredLocales can be null when called before the platform has had a chance to
// initialize the locales. Platforms without locale passing support will provide an empty list.
// We default to the first supported locale in these cases.
if (preferredLocales == null || preferredLocales.isEmpty) {
return supportedLocales.first;
}
// Hash the supported locales because apps can support many locales and would
// be expensive to search through them many times.
final Map<String, Locale> allSupportedLocales = HashMap<String, Locale>();
final Map<String, Locale> languageAndCountryLocales =
HashMap<String, Locale>();
final Map<String, Locale> languageAndScriptLocales =
HashMap<String, Locale>();
final Map<String, Locale> languageLocales = HashMap<String, Locale>();
final Map<String?, Locale> countryLocales = HashMap<String?, Locale>();
for (final Locale locale in supportedLocales) {
allSupportedLocales[
'${locale.languageCode}${locale.scriptCode}${locale.countryCode}'] ??=
locale;
languageAndScriptLocales[
'${locale.languageCode}${locale.scriptCode}'] ??= locale;
languageAndCountryLocales[
'${locale.languageCode}${locale.countryCode}'] ??= locale;
languageLocales[locale.languageCode] ??= locale;
countryLocales[locale.countryCode] ??= locale;
}
// Since languageCode-only matches are possibly low quality, we don't return
// it instantly when we find such a match. We check to see if the next
// preferred locale in the list has a high accuracy match, and only return
// the languageCode-only match when a higher accuracy match in the next
// preferred locale cannot be found.
Locale? matchesLanguageCode;
Locale? matchesCountryCode;
// Loop over user's preferred locales
for (int localeIndex = 0;
    localeIndex < preferredLocales.length;
    localeIndex += 1) {
  final Locale userLocale = preferredLocales[localeIndex];
  // Look for perfect match.
  if (allSupportedLocales.containsKey(
      '${userLocale.languageCode}_${userLocale.scriptCode}_${userLocale.countryCode}')) {
    return userLocale;
  }
  // Look for language+script match.
  if (userLocale.scriptCode != null) {
    final Locale? match = languageAndScriptLocales[
        '${userLocale.languageCode}_${userLocale.scriptCode}'];
    if (match != null) {
      return match;
    }
  }
  // Look for language+country match.
  if (userLocale.countryCode != null) {
    final Locale? match = languageAndCountryLocales[
        '${userLocale.languageCode}_${userLocale.countryCode}'];
    if (match != null) {
      return match;
    }
  }
  // If there was a languageCode-only match in the previous iteration's higher
  // ranked preferred locale, we return it if the current userLocale does not
  // have a better match.
  if (matchesLanguageCode != null) {
    return matchesLanguageCode;
  }
  // Look and store language-only match.
  Locale? match = languageLocales[userLocale.languageCode];
  if (match != null) {
    matchesLanguageCode = match;
    // Since first (default) locale is usually highly preferred, we will allow
    // a languageCode-only match to be instantly matched. If the next preferred
    // languageCode is the same, we defer hastily returning until the next iteration
    // since at worst it is the same and at best an improved match.
    if (localeIndex == 0 &&
        !(localeIndex + 1 < preferredLocales.length &&
            preferredLocales[localeIndex + 1].languageCode ==
                userLocale.languageCode)) {
      return matchesLanguageCode;
    }
  }
  // countryCode-only match. When all else except default supported locale fails,
  // attempt to match by country only, as a user is likely to be familiar with a
  // language from their listed country.
  if (matchesCountryCode == null && userLocale.countryCode != null) {
    match = countryLocales[userLocale.countryCode];
    if (match != null) {
      matchesCountryCode = match;
    }
  }
}
// When there is no languageCode-only match. Fallback to matching countryCode only. Country
// fallback only applies on iOS. When there is no countryCode-only match, we return first
// supported locale.
final Locale resolvedLocale =
    matchesLanguageCode ?? matchesCountryCode ?? supportedLocales.first;
return resolvedLocale;

}
@override
void didChangeLocales(List? locales) {
final Locale newLocale = _resolveLocales(locales, widget.supportedLocales);
if (newLocale != _locale) {
setState(() {
_locale = newLocale;
});
}
}
// Combine the Localizations for Widgets 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
// WidgetsLocalizations.delegate.
Iterable<LocalizationsDelegate> get _localizationsDelegates sync* {
if (widget.localizationsDelegates != null)
yield* widget.localizationsDelegates!;
yield DefaultWidgetsLocalizations.delegate;
}
// BUILDER
bool _debugCheckLocalizations(Locale appLocale) {
assert(() {
final Set unsupportedTypes = _localizationsDelegates
.map((LocalizationsDelegate delegate) => delegate.type)
.toSet();
for (final LocalizationsDelegate delegate
in _localizationsDelegates) {
if (!unsupportedTypes.contains(delegate.type)) continue;
if (delegate.isSupported(appLocale))
unsupportedTypes.remove(delegate.type);
}
if (unsupportedTypes.isEmpty) return true;
  // Currently the Cupertino library only provides english localizations.
  // Remove this when https://github.com/flutter/flutter/issues/23847
  // is fixed.
  if (listEquals(
      unsupportedTypes.map((Type type) => type.toString()).toList(),
      <String>['CupertinoLocalizations'])) return true;

  final StringBuffer message = StringBuffer();
  message.writeln('\u2550' * 8);
  message.writeln(
    "Warning: This application's locale, $appLocale, is not supported by all of its\n"
    'localization delegates.',
  );
  for (final Type unsupportedType in unsupportedTypes) {
    // Currently the Cupertino library only provides english localizations.
    // Remove this when https://github.com/flutter/flutter/issues/23847
    // is fixed.
    if (unsupportedType.toString() == 'CupertinoLocalizations') continue;
    message.writeln(
      '> A $unsupportedType delegate that supports the $appLocale locale was not found.',
    );
  }
  message.writeln(
    'See https://flutter.dev/tutorials/internationalization/ for more\n'
    "information about configuring an app's locale, supportedLocales,\n"
    'and localizationsDelegates parameters.',
  );
  message.writeln('\u2550' * 8);
  debugPrint(message.toString());
  return true;
}());
return true;

}
@override
Widget build(BuildContext context) {
Widget? routing;
if (_usesRouter) {
assert(_effectiveRouteInformationProvider != null);
routing = Router(
routeInformationProvider: _effectiveRouteInformationProvider,
routeInformationParser: widget.routeInformationParser,
routerDelegate: widget.routerDelegate!,
backButtonDispatcher: widget.backButtonDispatcher,
);
} else if (_usesNavigator) {
assert(_navigator != null);
routing = Navigator(
restorationScopeId: 'nav',
key: _navigator,
initialRoute: _initialRouteName,
onGenerateRoute: _onGenerateRoute,
onGenerateInitialRoutes: widget.onGenerateInitialRoutes == null
? Navigator.defaultGenerateInitialRoutes
: (NavigatorState navigator, String initialRouteName) {
return widget.onGenerateInitialRoutes!(initialRouteName);
},
onUnknownRoute: _onUnknownRoute,
observers: widget.navigatorObservers!,
reportsRouteUpdateToEngine: true,
);
}
Widget result;
if (widget.builder != null) {
  result = Builder(
    builder: (BuildContext context) {
      return widget.builder!(context, routing);
    },
  );
} else {
  assert(routing != null);
  result = routing!;
}

if (widget.textStyle != null) {
  result = DefaultTextStyle(
    style: widget.textStyle!,
    child: result,
  );
}

PerformanceOverlay? performanceOverlay;
// We need to push a performance overlay if any of the display or checkerboarding
// options are set.
if (widget.showPerformanceOverlay ||
    WidgetsApp.showPerformanceOverlayOverride) {
  performanceOverlay = PerformanceOverlay.allEnabled(
    checkerboardRasterCacheImages: widget.checkerboardRasterCacheImages,
    checkerboardOffscreenLayers: widget.checkerboardOffscreenLayers,
  );
} else if (widget.checkerboardRasterCacheImages ||
    widget.checkerboardOffscreenLayers) {
  performanceOverlay = PerformanceOverlay(
    checkerboardRasterCacheImages: widget.checkerboardRasterCacheImages,
    checkerboardOffscreenLayers: widget.checkerboardOffscreenLayers,
  );
}
if (performanceOverlay != null) {
  result = Stack(
    children: <Widget>[
      result,
      Positioned(
          top: 0.0, left: 0.0, right: 0.0, child: performanceOverlay),
    ],
  );
}

if (widget.showSemanticsDebugger) {
  result = SemanticsDebugger(
    child: result,
  );
}

assert(() {
  if (widget.debugShowWidgetInspector ||
      WidgetsApp.debugShowWidgetInspectorOverride) {
    result = WidgetInspector(
      child: result,
      selectButtonBuilder: widget.inspectorSelectButtonBuilder,
    );
  }
  if (widget.debugShowCheckedModeBanner &&
      WidgetsApp.debugAllowBannerOverride) {
    result = CheckedModeBanner(
      child: result,
    );
  }
  return true;
}());

final Widget title;
if (widget.onGenerateTitle != null) {
  title = Builder(
    // This Builder exists to provide a context below the Localizations widget.
    // The onGenerateTitle callback can refer to Localizations via its context
    // parameter.
    builder: (BuildContext context) {
      final String title = widget.onGenerateTitle!(context);
      assert(
          title != null, 'onGenerateTitle must return a non-null String');
      return Title(
        title: title,
        color: widget.color,
        child: result,
      );
    },
  );
} else {
  title = Title(
    title: widget.title,
    color: widget.color,
    child: result,
  );
}

final Locale appLocale = widget.locale != null
    ? _resolveLocales(<Locale>[widget.locale!], widget.supportedLocales)
    : _locale!;

assert(_debugCheckLocalizations(appLocale));

return RootRestorationScope(
  restorationId: widget.restorationScopeId,
  child: Shortcuts(
    debugLabel: '<Default WidgetsApp Shortcuts>',
    shortcuts: widget.shortcuts ?? WidgetsApp.defaultShortcuts,
    // DefaultTextEditingShortcuts is nested inside Shortcuts so that it can
    // fall through to the defaultShortcuts.
    child: DefaultTextEditingShortcuts(
      child: Actions(
        actions: widget.actions ?? WidgetsApp.defaultActions,
        child: DefaultTextEditingActions(
          child: FocusTraversalGroup(
            policy: ReadingOrderTraversalPolicy(),
            child: _MediaQueryFromWindow(
              child: Localizations(
                locale: appLocale,
                delegates: _localizationsDelegates.toList(),
                child: title,
              ),
            ),
          ),
        ),
      ),
    ),
  ),
);

}
}
/// Builds [MediaQuery] from window by listening to [WidgetsBinding].
///
/// It is performed in a standalone widget to rebuild only [MediaQuery] and
/// its dependents when window changes, instead of rebuilding the entire widget tree.
class _MediaQueryFromWindow extends StatefulWidget {
const _MediaQueryFromWindow({Key? key, required this.child})
: super(key: key);
final Widget child;
@override
_MediaQueryFromWindowsState createState() => _MediaQueryFromWindowsState();
}
class _MediaQueryFromWindowsState extends State<_MediaQueryFromWindow>
with WidgetsBindingObserver {
@override
void initState() {
super.initState();
WidgetsBinding.instance!.addObserver(this);
}
// ACCESSIBILITY
@override
void didChangeAccessibilityFeatures() {
setState(() {
// The properties of window have changed. We use them in our build
// function, so we need setState(), but we don't cache anything locally.
});
}
// METRICS
@override
void didChangeMetrics() {
setState(() {
// The properties of window have changed. We use them in our build
// function, so we need setState(), but we don't cache anything locally.
});
}
@override
void didChangeTextScaleFactor() {
setState(() {
// The textScaleFactor property of window has changed. We reference
// window in our build function, so we need to call setState(), but
// we don't need to cache anything locally.
});
}
// RENDERING
@override
void didChangePlatformBrightness() {
setState(() {
// The platformBrightness property of window has changed. We reference
// window in our build function, so we need to call setState(), but
// we don't need to cache anything locally.
});
}
@override
Widget build(BuildContext context) {
MediaQueryData data =
MediaQueryData.fromWindow(WidgetsBinding.instance!.window);
if (!kReleaseMode) {
data = data.copyWith(platformBrightness: debugBrightnessOverride);
}
return MediaQuery(
data: data,
child: widget.child,
);
}
@override
void dispose() {
WidgetsBinding.instance!.removeObserver(this);
super.dispose();
}
}

perdon el anterior code se tradujor por el tranductor del chrome
este el el code
import 'dart:collection' show HashMap;
import 'package:flutter/foundation.dart';
import 'package:flutter/rendering.dart';
import 'package:flutter/services.dart';
import 'actions.dart';
import 'banner.dart';
import 'basic.dart';
import 'binding.dart';
import 'default_text_editing_actions.dart';
import 'default_text_editing_shortcuts.dart';
import 'focus_traversal.dart';
import 'framework.dart';
import 'localizations.dart';
import 'media_query.dart';
import 'navigator.dart';
import 'pages.dart';
import 'performance_overlay.dart';
import 'restoration.dart';
import 'router.dart';
import 'scrollable.dart';
import 'semantics_debugger.dart';
import 'shortcuts.dart';
import 'text.dart';
import 'title.dart';
import 'widget_inspector.dart';
export 'dart:ui' show Locale;
/// The signature of [WidgetsApp.localeListResolutionCallback].
///
/// A [LocaleListResolutionCallback] is responsible for computing the locale of the app's
/// [Localizations] object when the app starts and when user changes the list of
/// locales for the device.
///
/// The [locales] list is the device's preferred locales when the app started, or the
/// device's preferred locales the user selected after the app was started. This list
/// is in order of preference. If this list is null or empty, then Flutter has not yet
/// received the locale information from the platform. The [supportedLocales] parameter
/// is just the value of [WidgetsApp.supportedLocales].
///
/// See also:
///
///  * [LocaleResolutionCallback], which takes only one default locale (instead of a list)
///    and is attempted only after this callback fails or is null. [LocaleListResolutionCallback]
///    is recommended over [LocaleResolutionCallback].
typedef LocaleListResolutionCallback = Locale? Function(
List? locales, Iterable supportedLocales);
/// {@template flutter.widgets.LocaleResolutionCallback}
/// The signature of [WidgetsApp.localeResolutionCallback].
///
/// It is recommended to provide a [LocaleListResolutionCallback] instead of a
/// [LocaleResolutionCallback] when possible, as [LocaleResolutionCallback] only
/// receives a subset of the information provided in [LocaleListResolutionCallback].
///
/// A [LocaleResolutionCallback] is responsible for computing the locale of the app's
/// [Localizations] object when the app starts and when user changes the default
/// locale for the device after [LocaleListResolutionCallback] fails or is not provided.
///
/// This callback is also used if the app is created with a specific locale using
/// the [new WidgetsApp] locale parameter.
///
/// The [locale] is either the value of [WidgetsApp.locale], or the device's default
/// locale when the app started, or the device locale the user selected after the app
/// was started. The default locale is the first locale in the list of preferred
/// locales. If [locale] is null, then Flutter has not yet received the locale
/// information from the platform. The [supportedLocales] parameter is just the value of
/// [WidgetsApp.supportedLocales].
///
/// See also:
///
///  * [LocaleListResolutionCallback], which takes a list of preferred locales (instead of one locale).
///    Resolutions by [LocaleListResolutionCallback] take precedence over [LocaleResolutionCallback].
/// {@endtemplate}
typedef LocaleResolutionCallback = Locale? Function(
Locale? locale, Iterable supportedLocales);
/// The signature of [WidgetsApp.onGenerateTitle].
///
/// Used to generate a value for the app's [Title.title], which the device uses
/// to identify the app for the user. The context includes the [WidgetsApp]'s
/// [Localizations] widget so that this method can be used to produce a
/// localized title.
///
/// This function must not return null.
typedef GenerateAppTitle = String Function(BuildContext context);
/// The signature of [WidgetsApp.pageRouteBuilder].
///
/// Creates a [PageRoute] using the given [RouteSettings] and [WidgetBuilder].
typedef PageRouteFactory = PageRoute Function(
RouteSettings settings, WidgetBuilder builder);
/// The signature of [WidgetsApp.onGenerateInitialRoutes].
///
/// Creates a series of one or more initial routes.
typedef InitialRouteListFactory = List<Route> Function(
String initialRoute);
/// A convenience widget that wraps a number of widgets that are commonly
/// required for an application.
///
/// One of the primary roles that [WidgetsApp] provides is binding the system
/// back button to popping the [Navigator] or quitting the application.
///
/// It is used by both [MaterialApp] and [CupertinoApp] to implement base
/// functionality for an app.
///
/// Find references to many of the widgets that [WidgetsApp] wraps in the "See
/// also" section.
///
/// See also:
///
///  * [CheckedModeBanner], which displays a [Banner] saying "DEBUG" when
///    running in checked mode.
///  * [DefaultTextStyle], the text style to apply to descendant [Text] widgets
///    without an explicit style.
///  * [MediaQuery], which establishes a subtree in which media queries resolve
///    to a [MediaQueryData].
///  * [Localizations], which defines the [Locale] for its child.
///  * [Title], a widget that describes this app in the operating system.
///  * [Navigator], a widget that manages a set of child widgets with a stack
///    discipline.
///  * [Overlay], a widget that manages a [Stack] of entries that can be managed
///    independently.
///  * [SemanticsDebugger], a widget that visualizes the semantics for the child.
class WidgetsApp extends StatefulWidget {
/// Creates a widget that wraps a number of widgets that are commonly
/// required for an application.
///
/// The boolean arguments, [color], and [navigatorObservers] must not be null.
///
/// Most callers will want to use the [home] or [routes] parameters, or both.
/// The [home] parameter is a convenience for the following [routes] map:
///
/// dart   /// <String, WidgetBuilder>{ '/': (BuildContext context) => myWidget }   ///
///
/// It is possible to specify both [home] and [routes], but only if [routes] does
///  not contain an entry for '/'.  Conversely, if [home] is omitted, [routes]
/// must contain an entry for '/'.
///
/// If [home] or [routes] are not null, the routing implementation needs to know how
/// appropriately build [PageRoute]s. This can be achieved by supplying the
/// [pageRouteBuilder] parameter.  The [pageRouteBuilder] is used by [MaterialApp]
/// and [CupertinoApp] to create [MaterialPageRoute]s and [CupertinoPageRoute],
/// respectively.
///
/// The [builder] parameter is designed to provide the ability to wrap the visible
/// content of the app in some other widget. It is recommended that you use [home]
/// rather than [builder] if you intend to only display a single route in your app.
///
/// [WidgetsApp] is also possible to provide a custom implementation of routing via the
/// [onGenerateRoute] and [onUnknownRoute] parameters. These parameters correspond
/// to [Navigator.onGenerateRoute] and [Navigator.onUnknownRoute]. If [home], [routes],
/// and [builder] are null, or if they fail to create a requested route,
/// [onGenerateRoute] will be invoked.  If that fails, [onUnknownRoute] will be invoked.
///
/// The [pageRouteBuilder] will create a [PageRoute] that wraps newly built routes.
/// If the [builder] is non-null and the [onGenerateRoute] argument is null, then the
/// [builder] will not be provided only with the context and the child widget, whereas
/// the [pageRouteBuilder] will be provided with [RouteSettings]. If [onGenerateRoute]
/// is not provided, [navigatorKey], [onUnknownRoute], [navigatorObservers], and
/// [initialRoute] must have their default values, as they will have no effect.
///
/// The supportedLocales argument must be a list of one or more elements.
/// By default supportedLocales is [const Locale('en', 'US')].
WidgetsApp({
// can't be const because the asserts use methods on Iterable :-(
Key? key,
this.navigatorKey,
this.onGenerateRoute,
this.onGenerateInitialRoutes,
this.onUnknownRoute,
List this.navigatorObservers =
const [],
this.initialRoute,
this.pageRouteBuilder,
this.home,
Map<String, WidgetBuilder> this.routes = const <String, WidgetBuilder>{},
this.builder,
this.title = '',
this.onGenerateTitle,
this.textStyle,
required this.color,
this.locale,
this.localizationsDelegates,
this.localeListResolutionCallback,
this.localeResolutionCallback,
this.supportedLocales = const [Locale('en', 'US')],
this.showPerformanceOverlay = false,
this.checkerboardRasterCacheImages = false,
this.checkerboardOffscreenLayers = false,
this.showSemanticsDebugger = false,
this.debugShowWidgetInspector = false,
this.debugShowCheckedModeBanner = true,
this.inspectorSelectButtonBuilder,
this.shortcuts,
this.actions,
this.restorationScopeId,
})  : assert(navigatorObservers != null),
assert(routes != null),
assert(
home == null || onGenerateInitialRoutes == null,
'If onGenerateInitialRoutes is specified, the home argument will be '
'redundant.',
),
assert(
home == null || !routes.containsKey(Navigator.defaultRouteName),
'If the home property is specified, the routes table '
'cannot include an entry for "/", since it would be redundant.',
),
assert(
builder != null ||
home != null ||
routes.containsKey(Navigator.defaultRouteName) ||
onGenerateRoute != null ||
onUnknownRoute != null,
'Either the home property must be specified, '
'or the routes table must include an entry for "/", '
'or there must be on onGenerateRoute callback specified, '
'or there must be an onUnknownRoute callback specified, '
'or the builder property must be specified, '
'because otherwise there is nothing to fall back on if the '
'app is started with an intent that specifies an unknown route.',
),
assert(
(home != null ||
routes.isNotEmpty ||
onGenerateRoute != null ||
onUnknownRoute != null) ||
(builder != null &&
navigatorKey == null &&
initialRoute == null &&
navigatorObservers.isEmpty),
'If no route is provided using '
'home, routes, onGenerateRoute, or onUnknownRoute, '
'a non-null callback for the builder property must be provided, '
'and the other navigator-related properties, '
'navigatorKey, initialRoute, and navigatorObservers, '
'must have their initial values '
'(null, null, and the empty list, respectively).',
),
assert(
builder != null ||
onGenerateRoute != null ||
pageRouteBuilder != null,
'If neither builder nor onGenerateRoute are provided, the '
'pageRouteBuilder must be specified so that the default handler '
'will know what kind of PageRoute transition to build.',
),
assert(title != null),
assert(color != null),
assert(supportedLocales != null && supportedLocales.isNotEmpty),
assert(showPerformanceOverlay != null),
assert(checkerboardRasterCacheImages != null),
assert(checkerboardOffscreenLayers != null),
assert(showSemanticsDebugger != null),
assert(debugShowCheckedModeBanner != null),
assert(debugShowWidgetInspector != null),
routeInformationProvider = null,
routeInformationParser = null,
routerDelegate = null,
backButtonDispatcher = null,
super(key: key);
/// Creates a [WidgetsApp] that uses the [Router] instead of a [Navigator].
WidgetsApp.router({
Key? key,
this.routeInformationProvider,
required RouteInformationParser this.routeInformationParser,
required RouterDelegate this.routerDelegate,
BackButtonDispatcher? backButtonDispatcher,
this.builder,
this.title = '',
this.onGenerateTitle,
this.textStyle,
required this.color,
this.locale,
this.localizationsDelegates,
this.localeListResolutionCallback,
this.localeResolutionCallback,
this.supportedLocales = const [Locale('en', 'US')],
this.showPerformanceOverlay = false,
this.checkerboardRasterCacheImages = false,
this.checkerboardOffscreenLayers = false,
this.showSemanticsDebugger = false,
this.debugShowWidgetInspector = false,
this.debugShowCheckedModeBanner = true,
this.inspectorSelectButtonBuilder,
this.shortcuts,
this.actions,
this.restorationScopeId,
})  : assert(
routeInformationParser != null && routerDelegate != null,
'The routeInformationParser and routerDelegate cannot be null.',
),
assert(title != null),
assert(color != null),
assert(supportedLocales != null && supportedLocales.isNotEmpty),
assert(showPerformanceOverlay != null),
assert(checkerboardRasterCacheImages != null),
assert(checkerboardOffscreenLayers != null),
assert(showSemanticsDebugger != null),
assert(debugShowCheckedModeBanner != null),
assert(debugShowWidgetInspector != null),
navigatorObservers = null,
backButtonDispatcher =
backButtonDispatcher ?? RootBackButtonDispatcher(),
navigatorKey = null,
onGenerateRoute = null,
pageRouteBuilder = null,
home = null,
onGenerateInitialRoutes = null,
onUnknownRoute = null,
routes = null,
initialRoute = null,
super(key: key);
/// {@template flutter.widgets.widgetsApp.navigatorKey}
/// A key to use when building the [Navigator].
///
/// If a [navigatorKey] is specified, the [Navigator] can be directly
/// manipulated without first obtaining it from a [BuildContext] via
/// [Navigator.of]: from the [navigatorKey], use the [GlobalKey.currentState]
/// getter.
///
/// If this is changed, a new [Navigator] will be created, losing all the
/// application state in the process; in that case, the [navigatorObservers]
/// must also be changed, since the previous observers will be attached to the
/// previous navigator.
///
/// The [Navigator] is only built if [onGenerateRoute] is not null; if it is
/// null, [navigatorKey] must also be null.
/// {@endtemplate}
final GlobalKey? navigatorKey;
/// {@template flutter.widgets.widgetsApp.onGenerateRoute}
/// The route generator callback used when the app is navigated to a
/// named route.
///
/// If this returns null when building the routes to handle the specified
/// [initialRoute], then all the routes are discarded and
/// [Navigator.defaultRouteName] is used instead (/). See [initialRoute].
///
/// During normal app operation, the [onGenerateRoute] callback will only be
/// applied to route names pushed by the application, and so should never
/// return null.
///
/// This is used if [routes] does not contain the requested route.
///
/// The [Navigator] is only built if routes are provided (either via [home],
/// [routes], [onGenerateRoute], or [onUnknownRoute]); if they are not,
/// [builder] must not be null.
/// {@endtemplate}
///
/// If this property is not set, either the [routes] or [home] properties must
/// be set, and the [pageRouteBuilder] must also be set so that the
/// default handler will know what routes and [PageRoute]s to build.
final RouteFactory? onGenerateRoute;
/// {@template flutter.widgets.widgetsApp.onGenerateInitialRoutes}
/// The routes generator callback used for generating initial routes if
/// [initialRoute] is provided.
///
/// If this property is not set, the underlying
/// [Navigator.onGenerateInitialRoutes] will default to
/// [Navigator.defaultGenerateInitialRoutes].
/// {@endtemplate}
final InitialRouteListFactory? onGenerateInitialRoutes;
/// The [PageRoute] generator callback used when the app is navigated to a
/// named route.
///
/// This callback can be used, for example, to specify that a [MaterialPageRoute]
/// or a [CupertinoPageRoute] should be used for building page transitions.
final PageRouteFactory? pageRouteBuilder;
/// {@template flutter.widgets.widgetsApp.routeInformationParser}
/// A delegate to parse the route information from the
/// [routeInformationProvider] into a generic data type to be processed by
/// the [routerDelegate] at a later stage.
///
/// This object will be used by the underlying [Router].
///
/// The generic type T must match the generic type of the [routerDelegate].
///
/// See also:
///
///  * [Router.routeInformationParser]: which receives this object when this
///    widget builds the [Router].
/// {@endtemplate}
final RouteInformationParser? routeInformationParser;
/// {@template flutter.widgets.widgetsApp.routerDelegate}
/// A delegate that configures a widget, typically a [Navigator], with
/// parsed result from the [routeInformationParser].
///
/// This object will be used by the underlying [Router].
///
/// The generic type T must match the generic type of the
/// [routeInformationParser].
///
/// See also:
///
///  * [Router.routerDelegate]: which receives this object when this widget
///    builds the [Router].
/// {@endtemplate}
final RouterDelegate? routerDelegate;
/// {@template flutter.widgets.widgetsApp.backButtonDispatcher}
/// A delegate that decide whether to handle the Android back button intent.
///
/// This object will be used by the underlying [Router].
///
/// If this is not provided, the widgets app will create a
/// [RootBackButtonDispatcher] by default.
///
/// See also:
///
///  * [Router.backButtonDispatcher]: which receives this object when this
///    widget builds the [Router].
/// {@endtemplate}
final BackButtonDispatcher? backButtonDispatcher;
/// {@template flutter.widgets.widgetsApp.routeInformationProvider}
/// A object that provides route information through the
/// [RouteInformationProvider.value] and notifies its listener when its value
/// changes.
///
/// This object will be used by the underlying [Router].
///
/// If this is not provided, the widgets app will create a
/// [PlatformRouteInformationProvider] with initial route name equal to the
/// [dart:ui.PlatformDispatcher.defaultRouteName] by default.
///
/// See also:
///
///  * [Router.routeInformationProvider]: which receives this object when this
///    widget builds the [Router].
/// {@endtemplate}
final RouteInformationProvider? routeInformationProvider;
/// {@template flutter.widgets.widgetsApp.home}
/// The widget for the default route of the app ([Navigator.defaultRouteName],
/// which is /).
///
/// This is the route that is displayed first when the application is started
/// normally, unless [initialRoute] is specified. It's also the route that's
/// displayed if the [initialRoute] can't be displayed.
///
/// To be able to directly call [Theme.of], [MediaQuery.of], etc, in the code
/// that sets the [home] argument in the constructor, you can use a [Builder]
/// widget to get a [BuildContext].
///
/// If [home] is specified, then [routes] must not include an entry for /,
/// as [home] takes its place.
///
/// The [Navigator] is only built if routes are provided (either via [home],
/// [routes], [onGenerateRoute], or [onUnknownRoute]); if they are not,
/// [builder] must not be null.
///
/// The difference between using [home] and using [builder] is that the [home]
/// subtree is inserted into the application below a [Navigator] (and thus
/// below an [Overlay], which [Navigator] uses). With [home], therefore,
/// dialog boxes will work automatically, the [routes] table will be used, and
/// APIs such as [Navigator.push] and [Navigator.pop] will work as expected.
/// In contrast, the widget returned from [builder] is inserted above the
/// app's [Navigator] (if any).
/// {@endtemplate}
///
/// If this property is set, the [pageRouteBuilder] property must also be set
/// so that the default route handler will know what kind of [PageRoute]s to
/// build.
final Widget? home;
/// 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 [PageRoute] specified by
/// [pageRouteBuilder] to perform an appropriate transition, including [Hero]
/// animations, to the new route.
///
/// {@template flutter.widgets.widgetsApp.routes}
/// If the app only has one page, then you can specify it using [home] instead.
///
/// If [home] is specified, then it implies an entry in this table for the
/// [Navigator.defaultRouteName] route (/), and it is an error to
/// redundantly provide such a route in the [routes] table.
///
/// If a route is requested that is not specified in this table (or by
/// [home]), then the [onGenerateRoute] callback is called to build the page
/// instead.
///
/// The [Navigator] is only built if routes are provided (either via [home],
/// [routes], [onGenerateRoute], or [onUnknownRoute]); if they are not,
/// [builder] must not be null.
/// {@endtemplate}
///
/// If the routes map is not empty, the [pageRouteBuilder] property must be set
/// so that the default route handler will know what kind of [PageRoute]s to
/// build.
final Map<String, WidgetBuilder>? routes;
/// {@template flutter.widgets.widgetsApp.onUnknownRoute}
/// Called when [onGenerateRoute] fails to generate a route, except for the
/// [initialRoute].
///
/// This callback is typically used for error handling. For example, this
/// callback might always generate a "not found" page that describes the route
/// that wasn't found.
///
/// Unknown routes can arise either from errors in the app or from external
/// requests to push routes, such as from Android intents.
///
/// The [Navigator] is only built if routes are provided (either via [home],
/// [routes], [onGenerateRoute], or [onUnknownRoute]); if they are not,
/// [builder] must not be null.
/// {@endtemplate}
final RouteFactory? onUnknownRoute;
/// {@template flutter.widgets.widgetsApp.initialRoute}
/// The name of the first route to show, if a [Navigator] is built.
///
/// Defaults to [dart:ui.PlatformDispatcher.defaultRouteName], which may be
/// overridden by the code that launched the application.
///
/// If the route name starts with a slash, then it is treated as a "deep link",
/// and before this route is pushed, the routes leading to this one are pushed
/// also. For example, if the route was /a/b/c, then the app would start
/// with the four routes /, /a, /a/b, and /a/b/c loaded, in that order.
/// Even if the route was just /a, the app would start with / and /a
/// loaded. You can use the [onGenerateInitialRoutes] property to override
/// this behavior.
///
/// Intermediate routes aren't required to exist. In the example above, /a
/// and /a/b could be skipped if they have no matching route. But /a/b/c is
/// required to have a route, else [initialRoute] is ignored and
/// [Navigator.defaultRouteName] is used instead (/). This can happen if the
/// app is started with an intent that specifies a non-existent route.
///
/// The [Navigator] is only built if routes are provided (either via [home],
/// [routes], [onGenerateRoute], or [onUnknownRoute]); if they are not,
/// [initialRoute] must be null and [builder] must not be null.
///
/// See also:
///
///  * [Navigator.initialRoute], which is used to implement this property.
///  * [Navigator.push], for pushing additional routes.
///  * [Navigator.pop], for removing a route from the stack.
///
/// {@endtemplate}
final String? initialRoute;
/// {@template flutter.widgets.widgetsApp.navigatorObservers}
/// The list of observers for the [Navigator] created for this app.
///
/// This list must be replaced by a list of newly-created observers if the
/// [navigatorKey] is changed.
///
/// The [Navigator] is only built if routes are provided (either via [home],
/// [routes], [onGenerateRoute], or [onUnknownRoute]); if they are not,
/// [navigatorObservers] must be the empty list and [builder] must not be null.
/// {@endtemplate}
final List? navigatorObservers;
/// {@template flutter.widgets.widgetsApp.builder}
/// A builder for inserting widgets above the [Navigator] or - when the
/// [WidgetsApp.router] constructor is used - above the [Router] but below the
/// other widgets created by the [WidgetsApp] widget, or for replacing the
/// [Navigator]/[Router] entirely.
///
/// For example, from the [BuildContext] passed to this method, the
/// [Directionality], [Localizations], [DefaultTextStyle], [MediaQuery], etc,
/// are all available. They can also be overridden in a way that impacts all
/// the routes in the [Navigator] or [Router].
///
/// This is rarely useful, but can be used in applications that wish to
/// override those defaults, e.g. to force the application into right-to-left
/// mode despite being in English, or to override the [MediaQuery] metrics
/// (e.g. to leave a gap for advertisements shown by a plugin from OEM code).
///
/// For specifically overriding the [title] with a value based on the
/// [Localizations], consider [onGenerateTitle] instead.
///
/// The [builder] callback is passed two arguments, the [BuildContext] (as
/// context) and a [Navigator] or [Router] widget (as child).
///
/// If no routes are provided to the regular [WidgetsApp] constructor using
/// [home], [routes], [onGenerateRoute], or [onUnknownRoute], the child will
/// be null, and it is the responsibility of the [builder] to provide the
/// application's routing machinery.
///
/// If routes are provided to the regular [WidgetsApp] constructor using one
/// or more of those properties or if the [WidgetsApp.router] constructor is
/// used, then child is not null, and the returned value should include the
/// child in the widget subtree; if it does not, then the application will
/// have no [Navigator] or [Router] and the routing related properties (i.e.
/// [navigatorKey], [home], [routes], [onGenerateRoute], [onUnknownRoute],
/// [initialRoute], [navigatorObservers], [routeInformationProvider],
/// [backButtonDispatcher], [routerDelegate], and [routeInformationParser])
/// are ignored.
///
/// If [builder] is null, it is as if a builder was specified that returned
/// the child directly. If it is null, routes must be provided using one of
/// the other properties listed above.
///
/// Unless a [Navigator] is provided, either implicitly from [builder] being
/// null, or by a [builder] including its child argument, or by a [builder]
/// explicitly providing a [Navigator] of its own, or by the [routerDelegate]
/// building one, widgets and APIs such as [Hero], [Navigator.push] and
/// [Navigator.pop], will not function.
/// {@endtemplate}
final TransitionBuilder? builder;
/// {@template flutter.widgets.widgetsApp.title}
/// A one-line description used by the device to identify the app for the user.
///
/// On Android the titles appear above the task manager's app snapshots which are
/// displayed when the user presses the "recent apps" button. On iOS this
/// value cannot be used. CFBundleDisplayName from the app's Info.plist is
/// referred to instead whenever present, CFBundleName otherwise.
/// On the web it is used as the page title, which shows up in the browser's list of open tabs.
///
/// To provide a localized title instead, use [onGenerateTitle].
/// {@endtemplate}
final String title;
/// {@template flutter.widgets.widgetsApp.onGenerateTitle}
/// If non-null this callback function is called to produce the app's
/// title string, otherwise [title] is used.
///
/// The [onGenerateTitle] context parameter includes the [WidgetsApp]'s
/// [Localizations] widget so that this callback can be used to produce a
/// localized title.
///
/// This callback function must not return null.
///
/// The [onGenerateTitle] callback is called each time the [WidgetsApp]
/// rebuilds.
/// {@endtemplate}
final GenerateAppTitle? onGenerateTitle;
/// The default text style for [Text] in the application.
final TextStyle? textStyle;
/// {@template flutter.widgets.widgetsApp.color}
/// The primary color to use for the application in the operating system
/// interface.
///
/// For example, on Android this is the color used for the application in the
/// application switcher.
/// {@endtemplate}
final Color color;
/// {@template flutter.widgets.widgetsApp.locale}
/// The initial locale for this app's [Localizations] widget is based
/// on this value.
///
/// If the 'locale' is null then the system's locale value is used.
///
/// The value of [Localizations.locale] will equal this locale if
/// it matches one of the [supportedLocales]. Otherwise it will be
/// the first element of [supportedLocales].
/// {@endtemplate}
///
/// See also:
///
///  * [localeResolutionCallback], which can override the default
///    [supportedLocales] matching algorithm.
///  * [localizationsDelegates], which collectively define all of the localized
///    resources used by this app.
final Locale? locale;
/// {@template flutter.widgets.widgetsApp.localizationsDelegates}
/// The delegates for this app's [Localizations] widget.
///
/// The delegates collectively define all of the localized resources
/// for this application's [Localizations] widget.
/// {@endtemplate}
final Iterable<LocalizationsDelegate>? localizationsDelegates;
/// {@template flutter.widgets.widgetsApp.localeListResolutionCallback}
/// This callback is responsible for choosing the app's locale
/// when the app is started, and when the user changes the
/// device's locale.
///
/// When a [localeListResolutionCallback] is provided, Flutter will first
/// attempt to resolve the locale with the provided
/// [localeListResolutionCallback]. If the callback or result is null, it will
/// fallback to trying the [localeResolutionCallback]. If both
/// [localeResolutionCallback] and [localeListResolutionCallback] are left
/// null or fail to resolve (return null), the a basic fallback algorithm will
/// be used.
///
/// The priority of each available fallback is:
///
///  1. [localeListResolutionCallback] is attempted first.
///  1. [localeResolutionCallback] is attempted second.
///  1. Flutter's basic resolution algorithm, as described in
///     [supportedLocales], is attempted last.
///
/// Properly localized projects should provide a more advanced algorithm than
/// the basic method from [supportedLocales], as it does not implement a
/// complete algorithm (such as the one defined in
/// Unicode TR35)
/// and is optimized for speed at the detriment of some uncommon edge-cases.
/// {@endtemplate}
///
/// This callback considers the entire list of preferred locales.
///
/// This algorithm should be able to handle a null or empty list of preferred locales,
/// which indicates Flutter has not yet received locale information from the platform.
///
/// See also:
///
///  * [MaterialApp.localeListResolutionCallback], which sets the callback of the
///    [WidgetsApp] it creates.
final LocaleListResolutionCallback? localeListResolutionCallback;
/// {@macro flutter.widgets.widgetsApp.localeListResolutionCallback}
///
/// This callback considers only the default locale, which is the first locale
/// in the preferred locales list. It is preferred to set [localeListResolutionCallback]
/// over [localeResolutionCallback] as it provides the full preferred locales list.
///
/// This algorithm should be able to handle a null locale, which indicates
/// Flutter has not yet received locale information from the platform.
///
/// See also:
///
///  * [MaterialApp.localeResolutionCallback], which sets the callback of the
///    [WidgetsApp] it creates.
final LocaleResolutionCallback? localeResolutionCallback;
/// {@template flutter.widgets.widgetsApp.supportedLocales}
/// The list of locales that this app has been localized for.
///
/// By default only the American English locale is supported. Apps should
/// configure this list to match the locales they support.
///
/// This list must not null. Its default value is just
/// [const Locale('en', 'US')].
///
/// The order of the list matters. The default locale resolution algorithm,
/// basicLocaleListResolution, attempts to match by the following priority:
///
///  1. [Locale.languageCode], [Locale.scriptCode], and [Locale.countryCode]
///  2. [Locale.languageCode] and [Locale.scriptCode] only
///  3. [Locale.languageCode] and [Locale.countryCode] only
///  4. [Locale.languageCode] only
///  5. [Locale.countryCode] only when all preferred locales fail to match
///  6. Returns the first element of [supportedLocales] as a fallback
///
/// When more than one supported locale matches one of these criteria, only
/// the first matching locale is returned.
///
/// The default locale resolution algorithm can be overridden by providing a
/// value for [localeListResolutionCallback]. The provided
/// basicLocaleListResolution is optimized for speed and does not implement
/// a full algorithm (such as the one defined in
/// Unicode TR35) that
/// takes distances between languages into account.
///
/// When supporting languages with more than one script, it is recommended
/// to specify the [Locale.scriptCode] explicitly. Locales may also be defined without
/// [Locale.countryCode] to specify a generic fallback for a particular script.
///
/// A fully supported language with multiple scripts should define a generic language-only
/// locale (e.g. 'zh'), language+script only locales (e.g. 'zh_Hans' and 'zh_Hant'),
/// and any language+script+country locales (e.g. 'zh_Hans_CN'). Fully defining all of
/// these locales as supported is not strictly required but allows for proper locale resolution in
/// the most number of cases. These locales can be specified with the [Locale.fromSubtags]
/// constructor:
///
/// dart   /// // Full Chinese support for CN, TW, and HK   /// supportedLocales: [   ///   const Locale.fromSubtags(languageCode: 'zh'), // generic Chinese 'zh'   ///   const Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hans'), // generic simplified Chinese 'zh_Hans'   ///   const Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hant'), // generic traditional Chinese 'zh_Hant'   ///   const Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hans', countryCode: 'CN'), // 'zh_Hans_CN'   ///   const Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hant', countryCode: 'TW'), // 'zh_Hant_TW'   ///   const Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hant', countryCode: 'HK'), // 'zh_Hant_HK'   /// ],   ///
///
/// Omitting some these fallbacks may result in improperly resolved
/// edge-cases, for example, a simplified Chinese user in Taiwan ('zh_Hans_TW')
/// may resolve to traditional Chinese if 'zh_Hans' and 'zh_Hans_CN' are
/// omitted.
/// {@endtemplate}
///
/// See also:
///
///  * [MaterialApp.supportedLocales], which sets the supportedLocales
///    of the [WidgetsApp] it creates.
///  * [localeResolutionCallback], an app callback that resolves the app's locale
///    when the device's locale changes.
///  * [localizationsDelegates], which collectively define all of the localized
///    resources used by this app.
final Iterable supportedLocales;
/// Turns on a performance overlay.
///
/// See also:
///
///  * https://flutter.dev/debugging/#performanceoverlay
final bool showPerformanceOverlay;
/// Checkerboards raster cache images.
///
/// See [PerformanceOverlay.checkerboardRasterCacheImages].
final bool checkerboardRasterCacheImages;
/// Checkerboards layers rendered to offscreen bitmaps.
///
/// See [PerformanceOverlay.checkerboardOffscreenLayers].
final bool checkerboardOffscreenLayers;
/// Turns on an overlay that shows the accessibility information
/// reported by the framework.
final bool showSemanticsDebugger;
/// Turns on an overlay that enables inspecting the widget tree.
///
/// The inspector is only available in checked mode as it depends on
/// [RenderObject.debugDescribeChildren] which should not be called outside of
/// checked mode.
final bool debugShowWidgetInspector;
/// Builds the widget the [WidgetInspector] uses to switch between view and
/// inspect modes.
///
/// This lets [MaterialApp] to use a material button to toggle the inspector
/// select mode without requiring [WidgetInspector] to depend on the
/// material package.
final InspectorSelectButtonBuilder? inspectorSelectButtonBuilder;
/// {@template flutter.widgets.widgetsApp.debugShowCheckedModeBanner}
/// Turns on a little "DEBUG" banner in checked mode to indicate
/// that the app is in checked mode. This is on by default (in
/// checked mode), to turn it off, set the constructor argument to
/// false. In release mode this has no effect.
///
/// To get this banner in your application if you're not using
/// WidgetsApp, include a [CheckedModeBanner] widget in your app.
///
/// This banner is intended to deter people from complaining that your
/// app is slow when it's in checked mode. In checked mode, Flutter
/// enables a large number of expensive diagnostics to aid in
/// development, and so performance in checked mode is not
/// representative of what will happen in release mode.
/// {@endtemplate}
final bool debugShowCheckedModeBanner;
/// {@template flutter.widgets.widgetsApp.shortcuts}
/// The default map of keyboard shortcuts to intents for the application.
///
/// By default, this is set to [WidgetsApp.defaultShortcuts].
///
/// Passing this will not replace [DefaultTextEditingShortcuts]. These can be
/// overridden by using a [Shortcuts] widget lower in the widget tree.
/// {@endtemplate}
///
/// {@tool snippet}
/// This example shows how to add a single shortcut for
/// [LogicalKeyboardKey.select] to the default shortcuts without needing to
/// add your own [Shortcuts] widget.
///
/// Alternatively, you could insert a [Shortcuts] widget with just the mapping
/// you want to add between the [WidgetsApp] and its child and get the same
/// effect.
///
/// dart   /// Widget build(BuildContext context) {   ///   return WidgetsApp(   ///     shortcuts: <LogicalKeySet, Intent>{   ///       ... WidgetsApp.defaultShortcuts,   ///       LogicalKeySet(LogicalKeyboardKey.select): const ActivateIntent(),   ///     },   ///     color: const Color(0xFFFF0000),   ///     builder: (BuildContext context, Widget? child) {   ///       return const Placeholder();   ///     },   ///   );   /// }   ///
/// {@end-tool}
///
/// {@template flutter.widgets.widgetsApp.shortcuts.seeAlso}
/// See also:
///
///  * [LogicalKeySet], a set of [LogicalKeyboardKey]s that make up the keys
///    for this map.
///  * The [Shortcuts] widget, which defines a keyboard mapping.
///  * The [Actions] widget, which defines the mapping from intent to action.
///  * The [Intent] and [Action] classes, which allow definition of new
///    actions.
/// {@endtemplate}
final Map<LogicalKeySet, Intent>? shortcuts;
/// {@template flutter.widgets.widgetsApp.actions}
/// The default map of intent keys to actions for the application.
///
/// By default, this is the output of [WidgetsApp.defaultActions], called with
/// [defaultTargetPlatform]. Specifying [actions] for an app overrides the
/// default, so if you wish to modify the default [actions], you can call
/// [WidgetsApp.defaultActions] and modify the resulting map, passing it as
/// the [actions] for this app. You may also add to the bindings, or override
/// specific bindings for a widget subtree, by adding your own [Actions]
/// widget.
///
/// Passing this will not replace [DefaultTextEditingActions]. These can be
/// overridden by placing an [Actions] widget lower in the widget tree.
/// {@endtemplate}
///
/// {@tool snippet}
/// This example shows how to add a single action handling an
/// [ActivateAction] to the default actions without needing to
/// add your own [Actions] widget.
///
/// Alternatively, you could insert a [Actions] widget with just the mapping
/// you want to add between the [WidgetsApp] and its child and get the same
/// effect.
///
/// dart   /// Widget build(BuildContext context) {   ///   return WidgetsApp(   ///     actions: <Type, Action<Intent>>{   ///       ... WidgetsApp.defaultActions,   ///       ActivateAction: CallbackAction<Intent>(   ///         onInvoke: (Intent intent) {   ///           // Do something here...   ///           return null;   ///         },   ///       ),   ///     },   ///     color: const Color(0xFFFF0000),   ///     builder: (BuildContext context, Widget? child) {   ///       return const Placeholder();   ///     },   ///   );   /// }   ///
/// {@end-tool}
///
/// {@template flutter.widgets.widgetsApp.actions.seeAlso}
/// See also:
///
///  * The [shortcuts] parameter, which defines the default set of shortcuts
///    for the application.
///  * The [Shortcuts] widget, which defines a keyboard mapping.
///  * The [Actions] widget, which defines the mapping from intent to action.
///  * The [Intent] and [Action] classes, which allow definition of new
///    actions.
/// {@endtemplate}
final Map<Type, Action>? actions;
/// {@template flutter.widgets.widgetsApp.restorationScopeId}
/// The identifier to use for state restoration of this app.
///
/// Providing a restoration ID inserts a [RootRestorationScope] into the
/// widget hierarchy, which enables state restoration for descendant widgets.
///
/// Providing a restoration ID also enables the [Navigator] built by the
/// [WidgetsApp] to restore its state (i.e. to restore the history stack of
/// active [Route]s). See the documentation on [Navigator] for more details
/// around state restoration of [Route]s.
///
/// See also:
///
///  * [RestorationManager], which explains how state restoration works in
///    Flutter.
/// {@endtemplate}
final String? restorationScopeId;
/// If true, forces the performance overlay to be visible in all instances.
///
/// Used by the showPerformanceOverlay observatory extension.
static bool showPerformanceOverlayOverride = false;
/// If true, forces the widget inspector to be visible.
///
/// Used by the debugShowWidgetInspector debugging extension.
///
/// The inspector allows you to select a location on your device or emulator
/// and view what widgets and render objects associated with it. An outline of
/// the selected widget and some summary information is shown on device and
/// more detailed information is shown in the IDE or Observatory.
static bool debugShowWidgetInspectorOverride = false;
/// If false, prevents the debug banner from being visible.
///
/// Used by the debugAllowBanner observatory extension.
///
/// This is how flutter run turns off the banner when you take a screen shot
/// with "s".
static bool debugAllowBannerOverride = true;
static final Map<LogicalKeySet, Intent> _defaultShortcuts =
<LogicalKeySet, Intent>{
// Activation
LogicalKeySet(LogicalKeyboardKey.enter): const ActivateIntent(),
LogicalKeySet(LogicalKeyboardKey.space): const ActivateIntent(),
LogicalKeySet(LogicalKeyboardKey.gameButtonA): const ActivateIntent(),
// Dismissal
LogicalKeySet(LogicalKeyboardKey.escape): const DismissIntent(),

// Keyboard traversal.
LogicalKeySet(LogicalKeyboardKey.tab): const NextFocusIntent(),
LogicalKeySet(LogicalKeyboardKey.shift, LogicalKeyboardKey.tab):
    const PreviousFocusIntent(),
LogicalKeySet(LogicalKeyboardKey.arrowLeft):
    const DirectionalFocusIntent(TraversalDirection.left),
LogicalKeySet(LogicalKeyboardKey.arrowRight):
    const DirectionalFocusIntent(TraversalDirection.right),
LogicalKeySet(LogicalKeyboardKey.arrowDown):
    const DirectionalFocusIntent(TraversalDirection.down),
LogicalKeySet(LogicalKeyboardKey.arrowUp):
    const DirectionalFocusIntent(TraversalDirection.up),

// Scrolling
LogicalKeySet(LogicalKeyboardKey.control, LogicalKeyboardKey.arrowUp):
    const ScrollIntent(direction: AxisDirection.up),
LogicalKeySet(LogicalKeyboardKey.control, LogicalKeyboardKey.arrowDown):
    const ScrollIntent(direction: AxisDirection.down),
LogicalKeySet(LogicalKeyboardKey.control, LogicalKeyboardKey.arrowLeft):
    const ScrollIntent(direction: AxisDirection.left),
LogicalKeySet(LogicalKeyboardKey.control, LogicalKeyboardKey.arrowRight):
    const ScrollIntent(direction: AxisDirection.right),
LogicalKeySet(LogicalKeyboardKey.pageUp): const ScrollIntent(
    direction: AxisDirection.up, type: ScrollIncrementType.page),
LogicalKeySet(LogicalKeyboardKey.pageDown): const ScrollIntent(
    direction: AxisDirection.down, type: ScrollIncrementType.page),

};
// Default shortcuts for the web platform.
static final Map<LogicalKeySet, Intent> _defaultWebShortcuts =
<LogicalKeySet, Intent>{
// Activation
LogicalKeySet(LogicalKeyboardKey.space): const PrioritizedIntents(
orderedIntents: [
ActivateIntent(),
ScrollIntent(
direction: AxisDirection.down, type: ScrollIncrementType.page),
],
),
// On the web, enter activates buttons, but not other controls.
LogicalKeySet(LogicalKeyboardKey.enter): const ButtonActivateIntent(),
// Dismissal
LogicalKeySet(LogicalKeyboardKey.escape): const DismissIntent(),

// Keyboard traversal.
LogicalKeySet(LogicalKeyboardKey.tab): const NextFocusIntent(),
LogicalKeySet(LogicalKeyboardKey.shift, LogicalKeyboardKey.tab):
    const PreviousFocusIntent(),

// Scrolling
LogicalKeySet(LogicalKeyboardKey.arrowUp):
    const ScrollIntent(direction: AxisDirection.up),
LogicalKeySet(LogicalKeyboardKey.arrowDown):
    const ScrollIntent(direction: AxisDirection.down),
LogicalKeySet(LogicalKeyboardKey.arrowLeft):
    const ScrollIntent(direction: AxisDirection.left),
LogicalKeySet(LogicalKeyboardKey.arrowRight):
    const ScrollIntent(direction: AxisDirection.right),
LogicalKeySet(LogicalKeyboardKey.pageUp): const ScrollIntent(
    direction: AxisDirection.up, type: ScrollIncrementType.page),
LogicalKeySet(LogicalKeyboardKey.pageDown): const ScrollIntent(
    direction: AxisDirection.down, type: ScrollIncrementType.page),

};
// Default shortcuts for the macOS platform.
static final Map<LogicalKeySet, Intent> _defaultAppleOsShortcuts =
<LogicalKeySet, Intent>{
// Activation
LogicalKeySet(LogicalKeyboardKey.enter): const ActivateIntent(),
LogicalKeySet(LogicalKeyboardKey.space): const ActivateIntent(),
// Dismissal
LogicalKeySet(LogicalKeyboardKey.escape): const DismissIntent(),

// Keyboard traversal
LogicalKeySet(LogicalKeyboardKey.tab): const NextFocusIntent(),
LogicalKeySet(LogicalKeyboardKey.shift, LogicalKeyboardKey.tab):
    const PreviousFocusIntent(),
LogicalKeySet(LogicalKeyboardKey.arrowLeft):
    const DirectionalFocusIntent(TraversalDirection.left),
LogicalKeySet(LogicalKeyboardKey.arrowRight):
    const DirectionalFocusIntent(TraversalDirection.right),
LogicalKeySet(LogicalKeyboardKey.arrowDown):
    const DirectionalFocusIntent(TraversalDirection.down),
LogicalKeySet(LogicalKeyboardKey.arrowUp):
    const DirectionalFocusIntent(TraversalDirection.up),

// Scrolling
LogicalKeySet(LogicalKeyboardKey.meta, LogicalKeyboardKey.arrowUp):
    const ScrollIntent(direction: AxisDirection.up),
LogicalKeySet(LogicalKeyboardKey.meta, LogicalKeyboardKey.arrowDown):
    const ScrollIntent(direction: AxisDirection.down),
LogicalKeySet(LogicalKeyboardKey.meta, LogicalKeyboardKey.arrowLeft):
    const ScrollIntent(direction: AxisDirection.left),
LogicalKeySet(LogicalKeyboardKey.meta, LogicalKeyboardKey.arrowRight):
    const ScrollIntent(direction: AxisDirection.right),
LogicalKeySet(LogicalKeyboardKey.pageUp): const ScrollIntent(
    direction: AxisDirection.up, type: ScrollIncrementType.page),
LogicalKeySet(LogicalKeyboardKey.pageDown): const ScrollIntent(
    direction: AxisDirection.down, type: ScrollIncrementType.page),

};
/// Generates the default shortcut key bindings based on the
/// [defaultTargetPlatform].
///
/// Used by [WidgetsApp] to assign a default value to [WidgetsApp.shortcuts].
static Map<LogicalKeySet, Intent> get defaultShortcuts {
if (kIsWeb) {
return _defaultWebShortcuts;
}
switch (defaultTargetPlatform) {
  case TargetPlatform.android:
  case TargetPlatform.fuchsia:
  case TargetPlatform.linux:
  case TargetPlatform.windows:
    return _defaultShortcuts;
  case TargetPlatform.iOS:
  case TargetPlatform.macOS:
    return _defaultAppleOsShortcuts;
}

}
/// The default value of [WidgetsApp.actions].
static Map<Type, Action> defaultActions = <Type, Action>{
DoNothingIntent: DoNothingAction(),
DoNothingAndStopPropagationIntent: DoNothingAction(consumesKey: false),
RequestFocusIntent: RequestFocusAction(),
NextFocusIntent: NextFocusAction(),
PreviousFocusIntent: PreviousFocusAction(),
DirectionalFocusIntent: DirectionalFocusAction(),
ScrollIntent: ScrollAction(),
PrioritizedIntents: PrioritizedAction(),
};
@override
_WidgetsAppState createState() => _WidgetsAppState();
}
class _WidgetsAppState extends State with WidgetsBindingObserver {
// STATE LIFECYCLE
// If window.defaultRouteName isn't '/', we should assume it was set
// intentionally via setInitialRoute, and should override whatever is in
// [widget.initialRoute].
String get _initialRouteName => WidgetsBinding
.instance!.window.defaultRouteName !=
Navigator.defaultRouteName
? WidgetsBinding.instance!.window.defaultRouteName
: widget.initialRoute ?? WidgetsBinding.instance!.window.defaultRouteName;
@override
void initState() {
super.initState();
_updateRouting();
_locale = _resolveLocales(
WidgetsBinding.instance!.window.locales, widget.supportedLocales);
WidgetsBinding.instance!.addObserver(this);
}
@override
void didUpdateWidget(WidgetsApp oldWidget) {
super.didUpdateWidget(oldWidget);
_updateRouting(oldWidget: oldWidget);
}
@override
void dispose() {
WidgetsBinding.instance!.removeObserver(this);
_defaultRouteInformationProvider?.dispose();
super.dispose();
}
void _updateRouting({WidgetsApp? oldWidget}) {
if (_usesRouter) {
assert(!_usesNavigator);
_navigator = null;
if (oldWidget == null ||
oldWidget.routeInformationProvider !=
widget.routeInformationProvider) {
_defaultRouteInformationProvider?.dispose();
_defaultRouteInformationProvider = null;
if (widget.routeInformationProvider == null) {
_defaultRouteInformationProvider = PlatformRouteInformationProvider(
initialRouteInformation: RouteInformation(
location: _initialRouteName,
),
);
}
}
} else if (_usesNavigator) {
assert(!_usesRouter);
_defaultRouteInformationProvider?.dispose();
_defaultRouteInformationProvider = null;
if (oldWidget == null || widget.navigatorKey != oldWidget.navigatorKey) {
_navigator =
widget.navigatorKey ?? GlobalObjectKey(this);
}
assert(_navigator != null);
} else {
assert(widget.builder != null);
assert(!_usesRouter);
assert(!_usesNavigator);
_navigator = null;
_defaultRouteInformationProvider?.dispose();
_defaultRouteInformationProvider = null;
}
// If we use a navigator, we have a navigator key.
assert(_usesNavigator == (_navigator != null));
}
bool get _usesRouter => widget.routerDelegate != null;
bool get _usesNavigator =>
widget.home != null ||
widget.routes?.isNotEmpty == true ||
widget.onGenerateRoute != null ||
widget.onUnknownRoute != null;
// ROUTER
RouteInformationProvider? get _effectiveRouteInformationProvider =>
widget.routeInformationProvider ?? _defaultRouteInformationProvider;
PlatformRouteInformationProvider? _defaultRouteInformationProvider;
// NAVIGATOR
GlobalKey? _navigator;
Route? _onGenerateRoute(RouteSettings settings) {
final String? name = settings.name;
final WidgetBuilder? pageContentBuilder =
name == Navigator.defaultRouteName && widget.home != null
? (BuildContext context) => widget.home!
: widget.routes![name];
if (pageContentBuilder != null) {
  assert(
    widget.pageRouteBuilder != null,
    'The default onGenerateRoute handler for WidgetsApp must have a '
    'pageRouteBuilder set if the home or routes properties are set.',
  );
  final Route<dynamic> route = widget.pageRouteBuilder!<dynamic>(
    settings,
    pageContentBuilder,
  );
  assert(route != null,
      'The pageRouteBuilder for WidgetsApp must return a valid non-null Route.');
  return route;
}
if (widget.onGenerateRoute != null)
  return widget.onGenerateRoute!(settings);
return null;

}
Route _onUnknownRoute(RouteSettings settings) {
assert(() {
if (widget.onUnknownRoute == null) {
throw FlutterError(
'Could not find a generator for route $settings in the $runtimeType.\n'
'Make sure your root app widget has provided a way to generate \n'
'this route.\n'
'Generators for routes are searched for in the following order:\n'
' 1. For the "/" route, the "home" property, if non-null, is used.\n'
' 2. Otherwise, the "routes" table is used, if it has an entry for '
'the route.\n'
' 3. Otherwise, onGenerateRoute is called. It should return a '
'non-null value for any valid route not handled by "home" and "routes".\n'
' 4. Finally if all else fails onUnknownRoute is called.\n'
'Unfortunately, onUnknownRoute was not set.',
);
}
return true;
}());
final Route? result = widget.onUnknownRoute!(settings);
assert(() {
if (result == null) {
throw FlutterError(
'The onUnknownRoute callback returned null.\n'
'When the $runtimeType requested the route $settings from its '
'onUnknownRoute callback, the callback returned null. Such callbacks '
'must never return null.',
);
}
return true;
}());
return result!;
}
// On Android: the user has pressed the back button.
@override
Future didPopRoute() async {
assert(mounted);
// The back button dispatcher should handle the pop route if we use a
// router.
if (_usesRouter) return false;
final NavigatorState? navigator = _navigator?.currentState;
if (navigator == null) return false;
return navigator.maybePop();

}
@override
Future didPushRoute(String route) async {
assert(mounted);
// The route name provider should handle the push route if we uses a
// router.
if (_usesRouter) return false;
final NavigatorState? navigator = _navigator?.currentState;
if (navigator == null) return false;
navigator.pushNamed(route);
return true;

}
// LOCALIZATION
/// This is the resolved locale, and is one of the supportedLocales.
Locale? _locale;
Locale _resolveLocales(
List? preferredLocales, Iterable supportedLocales) {
// Attempt to use localeListResolutionCallback.
if (widget.localeListResolutionCallback != null) {
final Locale? locale = widget.localeListResolutionCallback!(
preferredLocales, widget.supportedLocales);
if (locale != null) return locale;
}
// localeListResolutionCallback failed, falling back to localeResolutionCallback.
if (widget.localeResolutionCallback != null) {
final Locale? locale = widget.localeResolutionCallback!(
preferredLocales != null && preferredLocales.isNotEmpty
? preferredLocales.first
: null,
widget.supportedLocales,
);
if (locale != null) return locale;
}
// Both callbacks failed, falling back to default algorithm.
return basicLocaleListResolution(preferredLocales, supportedLocales);
}
/// The default locale resolution algorithm.
///
/// Custom resolution algorithms can be provided through
/// [WidgetsApp.localeListResolutionCallback] or
/// [WidgetsApp.localeResolutionCallback].
///
/// When no custom locale resolution algorithms are provided or if both fail
/// to resolve, Flutter will default to calling this algorithm.
///
/// This algorithm prioritizes speed at the cost of slightly less appropriate
/// resolutions for edge cases.
///