packages/flutter/lib/src/cupertino/tab_view.dart - mirrors/flutter - Git at Google

 // Copyright 2014 The Flutter Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 import 'package:flutter/widgets.dart';

 import 'app.dart' show CupertinoApp;
 import 'route.dart';

 /// A single tab view with its own [Navigator] state and history.
 ///
 /// A typical tab view is used as the content of each tab in a
 /// [CupertinoTabScaffold] where multiple tabs with parallel navigation states
 /// and history can co-exist.
 ///
 /// [CupertinoTabView] configures the top-level [Navigator] to search for routes
 /// in the following order:
 ///
 ///  1. For the `/` route, the [builder] property, if non-null, is used.
 ///
 ///  2. Otherwise, the [routes] table is used, if it has an entry for the route,
 ///     including `/` if [builder] is not specified.
 ///
 ///  3. Otherwise, [onGenerateRoute] is called, if provided. It should return a
 ///     non-null value for any _valid_ route not handled by [builder] and [routes].
 ///
 ///  4. Finally if all else fails [onUnknownRoute] is called.
 ///
 /// These navigation properties are not shared with any sibling [CupertinoTabView]
 /// nor any ancestor or descendant [Navigator] instances.
 ///
 /// To push a route above this [CupertinoTabView] instead of inside it (such
 /// as when showing a dialog on top of all tabs), use
 /// `Navigator.of(rootNavigator: true)`.
 ///
 /// See also:
 ///
 ///  * [CupertinoTabScaffold], a typical host that supports switching between tabs.
 ///  * [CupertinoPageRoute], a typical modal page route pushed onto the
 ///    [CupertinoTabView]'s [Navigator].
 class CupertinoTabView extends StatefulWidget {
   /// Creates the content area for a tab in a [CupertinoTabScaffold].
   const CupertinoTabView({
     super.key,
     this.builder,
     this.navigatorKey,
     this.defaultTitle,
     this.routes,
     this.onGenerateRoute,
     this.onUnknownRoute,
     this.navigatorObservers = const <NavigatorObserver>[],
     this.restorationScopeId,
   }) : assert(navigatorObservers != null);

   /// The widget builder for the default route of the tab view
   /// ([Navigator.defaultRouteName], which is `/`).
   ///
   /// If a [builder] is specified, then [routes] must not include an entry for `/`,
   /// as [builder] takes its place.
   ///
   /// Rebuilding a [CupertinoTabView] with a different [builder] will not clear
   /// its current navigation stack or update its descendant. Instead, trigger a
   /// rebuild from a descendant in its subtree. This can be done via methods such
   /// as:
   ///
   ///  * Calling [State.setState] on a descendant [StatefulWidget]'s [State]
   ///  * Modifying an [InheritedWidget] that a descendant registered itself
   ///    as a dependent to.
   final WidgetBuilder? builder;

   /// A key to use when building this widget's [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
   /// tab's state in the process; in that case, the [navigatorObservers]
   /// must also be changed, since the previous observers will be attached to the
   /// previous navigator.
   final GlobalKey<NavigatorState>? navigatorKey;

   /// The title of the default route.
   final String? defaultTitle;

   /// This tab view's routing table.
   ///
   /// When a named route is pushed with [Navigator.pushNamed] inside this tab view,
   /// the route name is looked up in this map. If the name is present,
   /// the associated [widgets.WidgetBuilder] is used to construct a
   /// [CupertinoPageRoute] that performs an appropriate transition to the new
   /// route.
   ///
   /// If the tab view only has one page, then you can specify it using [builder] instead.
   ///
   /// If [builder] 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
   /// [builder]), then the [onGenerateRoute] callback is called to build the page
   /// instead.
   ///
   /// This routing table is not shared with any routing tables of ancestor or
   /// descendant [Navigator]s.
   final Map<String, WidgetBuilder>? routes;

   /// The route generator callback used when the tab view is navigated to a named route.
   ///
   /// This is used if [routes] does not contain the requested route.
   final RouteFactory? onGenerateRoute;

   /// Called when [onGenerateRoute] also fails to generate a route.
   ///
   /// 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.
   ///
   /// The default implementation pushes a route that displays an ugly error
   /// message.
   final RouteFactory? onUnknownRoute;

   /// The list of observers for the [Navigator] created in this tab view.
   ///
   /// This list of observers is not shared with ancestor or descendant [Navigator]s.
   final List<NavigatorObserver> navigatorObservers;

   /// Restoration ID to save and restore the state of the [Navigator] built by
   /// this [CupertinoTabView].
   ///
   /// {@macro flutter.widgets.navigator.restorationScopeId}
   final String? restorationScopeId;

   @override
   State<CupertinoTabView> createState() => _CupertinoTabViewState();
 }

 class _CupertinoTabViewState extends State<CupertinoTabView> {
   late HeroController _heroController;
   late List<NavigatorObserver> _navigatorObservers;

   @override
   void initState() {
     super.initState();
     _heroController = CupertinoApp.createCupertinoHeroController();
     _updateObservers();
   }

   @override
   void didUpdateWidget(CupertinoTabView oldWidget) {
     super.didUpdateWidget(oldWidget);
     if (widget.navigatorKey != oldWidget.navigatorKey
         || widget.navigatorObservers != oldWidget.navigatorObservers) {
       _updateObservers();
     }
   }

   void _updateObservers() {
     _navigatorObservers =
         List<NavigatorObserver>.of(widget.navigatorObservers)
           ..add(_heroController);
   }

   @override
   Widget build(BuildContext context) {
     return Navigator(
       key: widget.navigatorKey,
       onGenerateRoute: _onGenerateRoute,
       onUnknownRoute: _onUnknownRoute,
       observers: _navigatorObservers,
       restorationScopeId: widget.restorationScopeId,
     );
   }

   Route<dynamic>? _onGenerateRoute(RouteSettings settings) {
     final String? name = settings.name;
     WidgetBuilder? routeBuilder;
     String? title;
     if (name == Navigator.defaultRouteName && widget.builder != null) {
       routeBuilder = widget.builder;
       title = widget.defaultTitle;
     } else if (widget.routes != null) {
       routeBuilder = widget.routes![name];
     }
     if (routeBuilder != null) {
       return CupertinoPageRoute<dynamic>(
         builder: routeBuilder,
         title: title,
         settings: settings,
       );
     }
     if (widget.onGenerateRoute != null) {
       return widget.onGenerateRoute!(settings);
     }
     return null;
   }

   Route<dynamic>? _onUnknownRoute(RouteSettings settings) {
     assert(() {
       if (widget.onUnknownRoute == null) {
         throw FlutterError(
           'Could not find a generator for route $settings in the $runtimeType.\n'
           'Generators for routes are searched for in the following order:\n'
           ' 1. For the "/" route, the "builder" 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 "builder" and "routes".\n'
           ' 4. Finally if all else fails onUnknownRoute is called.\n'
           'Unfortunately, onUnknownRoute was not set.',
         );
       }
       return true;
     }());
     final Route<dynamic>? 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;
   }
 }
	// Copyright 2014 The Flutter Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	import 'package:flutter/widgets.dart';

	import 'app.dart' show CupertinoApp;
	import 'route.dart';

	/// A single tab view with its own [Navigator] state and history.
	///
	/// A typical tab view is used as the content of each tab in a
	/// [CupertinoTabScaffold] where multiple tabs with parallel navigation states
	/// and history can co-exist.
	///
	/// [CupertinoTabView] configures the top-level [Navigator] to search for routes
	/// in the following order:
	///
	/// 1. For the `/` route, the [builder] property, if non-null, is used.
	///
	/// 2. Otherwise, the [routes] table is used, if it has an entry for the route,
	/// including `/` if [builder] is not specified.
	///
	/// 3. Otherwise, [onGenerateRoute] is called, if provided. It should return a
	/// non-null value for any _valid_ route not handled by [builder] and [routes].
	///
	/// 4. Finally if all else fails [onUnknownRoute] is called.
	///
	/// These navigation properties are not shared with any sibling [CupertinoTabView]
	/// nor any ancestor or descendant [Navigator] instances.
	///
	/// To push a route above this [CupertinoTabView] instead of inside it (such
	/// as when showing a dialog on top of all tabs), use
	/// `Navigator.of(rootNavigator: true)`.
	///
	/// See also:
	///
	/// * [CupertinoTabScaffold], a typical host that supports switching between tabs.
	/// * [CupertinoPageRoute], a typical modal page route pushed onto the
	/// [CupertinoTabView]'s [Navigator].
	class CupertinoTabView extends StatefulWidget {
	/// Creates the content area for a tab in a [CupertinoTabScaffold].
	const CupertinoTabView({
	super.key,
	this.builder,
	this.navigatorKey,
	this.defaultTitle,
	this.routes,
	this.onGenerateRoute,
	this.onUnknownRoute,
	this.navigatorObservers = const <NavigatorObserver>[],
	this.restorationScopeId,
	}) : assert(navigatorObservers != null);

	/// The widget builder for the default route of the tab view
	/// ([Navigator.defaultRouteName], which is `/`).
	///
	/// If a [builder] is specified, then [routes] must not include an entry for `/`,
	/// as [builder] takes its place.
	///
	/// Rebuilding a [CupertinoTabView] with a different [builder] will not clear
	/// its current navigation stack or update its descendant. Instead, trigger a
	/// rebuild from a descendant in its subtree. This can be done via methods such
	/// as:
	///
	/// * Calling [State.setState] on a descendant [StatefulWidget]'s [State]
	/// * Modifying an [InheritedWidget] that a descendant registered itself
	/// as a dependent to.
	final WidgetBuilder? builder;

	/// A key to use when building this widget's [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
	/// tab's state in the process; in that case, the [navigatorObservers]
	/// must also be changed, since the previous observers will be attached to the
	/// previous navigator.
	final GlobalKey<NavigatorState>? navigatorKey;

	/// The title of the default route.
	final String? defaultTitle;

	/// This tab view's routing table.
	///
	/// When a named route is pushed with [Navigator.pushNamed] inside this tab view,
	/// the route name is looked up in this map. If the name is present,
	/// the associated [widgets.WidgetBuilder] is used to construct a
	/// [CupertinoPageRoute] that performs an appropriate transition to the new
	/// route.
	///
	/// If the tab view only has one page, then you can specify it using [builder] instead.
	///
	/// If [builder] 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
	/// [builder]), then the [onGenerateRoute] callback is called to build the page
	/// instead.
	///
	/// This routing table is not shared with any routing tables of ancestor or
	/// descendant [Navigator]s.
	final Map<String, WidgetBuilder>? routes;

	/// The route generator callback used when the tab view is navigated to a named route.
	///
	/// This is used if [routes] does not contain the requested route.
	final RouteFactory? onGenerateRoute;

	/// Called when [onGenerateRoute] also fails to generate a route.
	///
	/// 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.
	///
	/// The default implementation pushes a route that displays an ugly error
	/// message.
	final RouteFactory? onUnknownRoute;

	/// The list of observers for the [Navigator] created in this tab view.
	///
	/// This list of observers is not shared with ancestor or descendant [Navigator]s.
	final List<NavigatorObserver> navigatorObservers;

	/// Restoration ID to save and restore the state of the [Navigator] built by
	/// this [CupertinoTabView].
	///
	/// {@macro flutter.widgets.navigator.restorationScopeId}
	final String? restorationScopeId;

	@override
	State<CupertinoTabView> createState() => _CupertinoTabViewState();
	}

	class _CupertinoTabViewState extends State<CupertinoTabView> {
	late HeroController _heroController;
	late List<NavigatorObserver> _navigatorObservers;

	@override
	void initState() {
	super.initState();
	_heroController = CupertinoApp.createCupertinoHeroController();
	_updateObservers();
	}

	@override
	void didUpdateWidget(CupertinoTabView oldWidget) {
	super.didUpdateWidget(oldWidget);
	if (widget.navigatorKey != oldWidget.navigatorKey
	\|\| widget.navigatorObservers != oldWidget.navigatorObservers) {
	_updateObservers();
	}
	}

	void _updateObservers() {
	_navigatorObservers =
	List<NavigatorObserver>.of(widget.navigatorObservers)
	..add(_heroController);
	}

	@override
	Widget build(BuildContext context) {
	return Navigator(
	key: widget.navigatorKey,
	onGenerateRoute: _onGenerateRoute,
	onUnknownRoute: _onUnknownRoute,
	observers: _navigatorObservers,
	restorationScopeId: widget.restorationScopeId,
	);
	}

	Route<dynamic>? _onGenerateRoute(RouteSettings settings) {
	final String? name = settings.name;
	WidgetBuilder? routeBuilder;
	String? title;
	if (name == Navigator.defaultRouteName && widget.builder != null) {
	routeBuilder = widget.builder;
	title = widget.defaultTitle;
	} else if (widget.routes != null) {
	routeBuilder = widget.routes![name];
	}
	if (routeBuilder != null) {
	return CupertinoPageRoute<dynamic>(
	builder: routeBuilder,
	title: title,
	settings: settings,
	);
	}
	if (widget.onGenerateRoute != null) {
	return widget.onGenerateRoute!(settings);
	}
	return null;
	}

	Route<dynamic>? _onUnknownRoute(RouteSettings settings) {
	assert(() {
	if (widget.onUnknownRoute == null) {
	throw FlutterError(
	'Could not find a generator for route $settings in the $runtimeType.\n'
	'Generators for routes are searched for in the following order:\n'
	' 1. For the "/" route, the "builder" 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 "builder" and "routes".\n'
	' 4. Finally if all else fails onUnknownRoute is called.\n'
	'Unfortunately, onUnknownRoute was not set.',
	);
	}
	return true;
	}());
	final Route<dynamic>? 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;
	}
	}