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// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
import 'package:flute/services.dart';
import 'package:flute/widgets.dart';
import 'app_bar.dart';
import 'app_bar_theme.dart';
import 'color_scheme.dart';
import 'colors.dart';
import 'debug.dart';
import 'input_border.dart';
import 'input_decorator.dart';
import 'material_localizations.dart';
import 'scaffold.dart';
import 'text_field.dart';
import 'theme.dart';
/// Shows a full screen search page and returns the search result selected by
/// the user when the page is closed.
///
/// The search page consists of an app bar with a search field and a body which
/// can either show suggested search queries or the search results.
///
/// The appearance of the search page is determined by the provided
/// `delegate`. The initial query string is given by `query`, which defaults
/// to the empty string. When `query` is set to null, `delegate.query` will
/// be used as the initial query.
///
/// This method returns the selected search result, which can be set in the
/// [SearchDelegate.close] call. If the search page is closed with the system
/// back button, it returns null.
///
/// A given [SearchDelegate] can only be associated with one active [showSearch]
/// call. Call [SearchDelegate.close] before re-using the same delegate instance
/// for another [showSearch] call.
///
/// The `useRootNavigator` argument is used to determine whether to push the
/// search page to the [Navigator] furthest from or nearest to the given
/// `context`. By default, `useRootNavigator` is `false` and the search page
/// route created by this method is pushed to the nearest navigator to the
/// given `context`. It can not be `null`.
///
/// The transition to the search page triggered by this method looks best if the
/// screen triggering the transition contains an [AppBar] at the top and the
/// transition is called from an [IconButton] that's part of [AppBar.actions].
/// The animation provided by [SearchDelegate.transitionAnimation] can be used
/// to trigger additional animations in the underlying page while the search
/// page fades in or out. This is commonly used to animate an [AnimatedIcon] in
/// the [AppBar.leading] position e.g. from the hamburger menu to the back arrow
/// used to exit the search page.
///
/// ## Handling emojis and other complex characters
/// {@macro flutter.widgets.EditableText.onChanged}
///
/// See also:
///
/// * [SearchDelegate] to define the content of the search page.
Future<T?> showSearch<T>({
required BuildContext context,
required SearchDelegate<T> delegate,
String? query = '',
bool useRootNavigator = false,
}) {
delegate.query = query ?? delegate.query;
delegate._currentBody = _SearchBody.suggestions;
return Navigator.of(context, rootNavigator: useRootNavigator).push(_SearchPageRoute<T>(
delegate: delegate,
));
}
/// Delegate for [showSearch] to define the content of the search page.
///
/// The search page always shows an [AppBar] at the top where users can
/// enter their search queries. The buttons shown before and after the search
/// query text field can be customized via [SearchDelegate.buildLeading]
/// and [SearchDelegate.buildActions]. Additionally, a widget can be placed
/// across the bottom of the [AppBar] via [SearchDelegate.buildBottom].
///
/// The body below the [AppBar] can either show suggested queries (returned by
/// [SearchDelegate.buildSuggestions]) or - once the user submits a search - the
/// results of the search as returned by [SearchDelegate.buildResults].
///
/// [SearchDelegate.query] always contains the current query entered by the user
/// and should be used to build the suggestions and results.
///
/// The results can be brought on screen by calling [SearchDelegate.showResults]
/// and you can go back to showing the suggestions by calling
/// [SearchDelegate.showSuggestions].
///
/// Once the user has selected a search result, [SearchDelegate.close] should be
/// called to remove the search page from the top of the navigation stack and
/// to notify the caller of [showSearch] about the selected search result.
///
/// A given [SearchDelegate] can only be associated with one active [showSearch]
/// call. Call [SearchDelegate.close] before re-using the same delegate instance
/// for another [showSearch] call.
///
/// ## Handling emojis and other complex characters
/// {@macro flutter.widgets.EditableText.onChanged}
abstract class SearchDelegate<T> {
/// Constructor to be called by subclasses which may specify
/// [searchFieldLabel], either [searchFieldStyle] or [searchFieldDecorationTheme],
/// [keyboardType] and/or [textInputAction]. Only one of [searchFieldLabel]
/// and [searchFieldDecorationTheme] may be non-null.
///
/// {@tool snippet}
/// ```dart
/// class CustomSearchHintDelegate extends SearchDelegate<String> {
/// CustomSearchHintDelegate({
/// required String hintText,
/// }) : super(
/// searchFieldLabel: hintText,
/// keyboardType: TextInputType.text,
/// textInputAction: TextInputAction.search,
/// );
///
/// @override
/// Widget buildLeading(BuildContext context) => const Text('leading');
///
/// @override
/// PreferredSizeWidget buildBottom(BuildContext context) {
/// return const PreferredSize(
/// preferredSize: Size.fromHeight(56.0),
/// child: Text('bottom'));
/// }
///
/// @override
/// Widget buildSuggestions(BuildContext context) => const Text('suggestions');
///
/// @override
/// Widget buildResults(BuildContext context) => const Text('results');
///
/// @override
/// List<Widget> buildActions(BuildContext context) => <Widget>[];
/// }
/// ```
/// {@end-tool}
SearchDelegate({
this.searchFieldLabel,
this.searchFieldStyle,
this.searchFieldDecorationTheme,
this.keyboardType,
this.textInputAction = TextInputAction.search,
}) : assert(searchFieldStyle == null || searchFieldDecorationTheme == null);
/// Suggestions shown in the body of the search page while the user types a
/// query into the search field.
///
/// The delegate method is called whenever the content of [query] changes.
/// The suggestions should be based on the current [query] string. If the query
/// string is empty, it is good practice to show suggested queries based on
/// past queries or the current context.
///
/// Usually, this method will return a [ListView] with one [ListTile] per
/// suggestion. When [ListTile.onTap] is called, [query] should be updated
/// with the corresponding suggestion and the results page should be shown
/// by calling [showResults].
Widget buildSuggestions(BuildContext context);
/// The results shown after the user submits a search from the search page.
///
/// The current value of [query] can be used to determine what the user
/// searched for.
///
/// This method might be applied more than once to the same query.
/// If your [buildResults] method is computationally expensive, you may want
/// to cache the search results for one or more queries.
///
/// Typically, this method returns a [ListView] with the search results.
/// When the user taps on a particular search result, [close] should be called
/// with the selected result as argument. This will close the search page and
/// communicate the result back to the initial caller of [showSearch].
Widget buildResults(BuildContext context);
/// A widget to display before the current query in the [AppBar].
///
/// Typically an [IconButton] configured with a [BackButtonIcon] that exits
/// the search with [close]. One can also use an [AnimatedIcon] driven by
/// [transitionAnimation], which animates from e.g. a hamburger menu to the
/// back button as the search overlay fades in.
///
/// Returns null if no widget should be shown.
///
/// See also:
///
/// * [AppBar.leading], the intended use for the return value of this method.
Widget? buildLeading(BuildContext context);
/// Widgets to display after the search query in the [AppBar].
///
/// If the [query] is not empty, this should typically contain a button to
/// clear the query and show the suggestions again (via [showSuggestions]) if
/// the results are currently shown.
///
/// Returns null if no widget should be shown.
///
/// See also:
///
/// * [AppBar.actions], the intended use for the return value of this method.
List<Widget>? buildActions(BuildContext context);
/// Widget to display across the bottom of the [AppBar].
///
/// Returns null by default, i.e. a bottom widget is not included.
///
/// See also:
///
/// * [AppBar.bottom], the intended use for the return value of this method.
///
PreferredSizeWidget? buildBottom(BuildContext context) => null;
/// The theme used to configure the search page.
///
/// The returned [ThemeData] will be used to wrap the entire search page,
/// so it can be used to configure any of its components with the appropriate
/// theme properties.
///
/// Unless overridden, the default theme will configure the AppBar containing
/// the search input text field with a white background and black text on light
/// themes. For dark themes the default is a dark grey background with light
/// color text.
///
/// See also:
///
/// * [AppBarTheme], which configures the AppBar's appearance.
/// * [InputDecorationTheme], which configures the appearance of the search
/// text field.
ThemeData appBarTheme(BuildContext context) {
final ThemeData theme = Theme.of(context);
final ColorScheme colorScheme = theme.colorScheme;
return theme.copyWith(
appBarTheme: AppBarTheme(
systemOverlayStyle: colorScheme.brightness == Brightness.dark
? SystemUiOverlayStyle.light
: SystemUiOverlayStyle.dark,
backgroundColor: colorScheme.brightness == Brightness.dark ? Colors.grey[900] : Colors.white,
iconTheme: theme.primaryIconTheme.copyWith(color: Colors.grey),
titleTextStyle: theme.textTheme.titleLarge,
toolbarTextStyle: theme.textTheme.bodyMedium,
),
inputDecorationTheme: searchFieldDecorationTheme ??
InputDecorationTheme(
hintStyle: searchFieldStyle ?? theme.inputDecorationTheme.hintStyle,
border: InputBorder.none,
),
);
}
/// The current query string shown in the [AppBar].
///
/// The user manipulates this string via the keyboard.
///
/// If the user taps on a suggestion provided by [buildSuggestions] this
/// string should be updated to that suggestion via the setter.
String get query => _queryTextController.text;
/// Changes the current query string.
///
/// Setting the query string programmatically moves the cursor to the end of the text field.
set query(String value) {
_queryTextController.text = value;
if (_queryTextController.text.isNotEmpty) {
_queryTextController.selection = TextSelection.fromPosition(TextPosition(offset: _queryTextController.text.length));
}
}
/// Transition from the suggestions returned by [buildSuggestions] to the
/// [query] results returned by [buildResults].
///
/// If the user taps on a suggestion provided by [buildSuggestions] the
/// screen should typically transition to the page showing the search
/// results for the suggested query. This transition can be triggered
/// by calling this method.
///
/// See also:
///
/// * [showSuggestions] to show the search suggestions again.
void showResults(BuildContext context) {
_focusNode?.unfocus();
_currentBody = _SearchBody.results;
}
/// Transition from showing the results returned by [buildResults] to showing
/// the suggestions returned by [buildSuggestions].
///
/// Calling this method will also put the input focus back into the search
/// field of the [AppBar].
///
/// If the results are currently shown this method can be used to go back
/// to showing the search suggestions.
///
/// See also:
///
/// * [showResults] to show the search results.
void showSuggestions(BuildContext context) {
assert(_focusNode != null, '_focusNode must be set by route before showSuggestions is called.');
_focusNode!.requestFocus();
_currentBody = _SearchBody.suggestions;
}
/// Closes the search page and returns to the underlying route.
///
/// The value provided for `result` is used as the return value of the call
/// to [showSearch] that launched the search initially.
void close(BuildContext context, T result) {
_currentBody = null;
_focusNode?.unfocus();
Navigator.of(context)
..popUntil((Route<dynamic> route) => route == _route)
..pop(result);
}
/// The hint text that is shown in the search field when it is empty.
///
/// If this value is set to null, the value of
/// `MaterialLocalizations.of(context).searchFieldLabel` will be used instead.
final String? searchFieldLabel;
/// The style of the [searchFieldLabel].
///
/// If this value is set to null, the value of the ambient [Theme]'s
/// [InputDecorationTheme.hintStyle] will be used instead.
///
/// Only one of [searchFieldStyle] or [searchFieldDecorationTheme] can
/// be non-null.
final TextStyle? searchFieldStyle;
/// The [InputDecorationTheme] used to configure the search field's visuals.
///
/// Only one of [searchFieldStyle] or [searchFieldDecorationTheme] can
/// be non-null.
final InputDecorationTheme? searchFieldDecorationTheme;
/// The type of action button to use for the keyboard.
///
/// Defaults to the default value specified in [TextField].
final TextInputType? keyboardType;
/// The text input action configuring the soft keyboard to a particular action
/// button.
///
/// Defaults to [TextInputAction.search].
final TextInputAction textInputAction;
/// [Animation] triggered when the search pages fades in or out.
///
/// This animation is commonly used to animate [AnimatedIcon]s of
/// [IconButton]s returned by [buildLeading] or [buildActions]. It can also be
/// used to animate [IconButton]s contained within the route below the search
/// page.
Animation<double> get transitionAnimation => _proxyAnimation;
// The focus node to use for manipulating focus on the search page. This is
// managed, owned, and set by the _SearchPageRoute using this delegate.
FocusNode? _focusNode;
final TextEditingController _queryTextController = TextEditingController();
final ProxyAnimation _proxyAnimation = ProxyAnimation(kAlwaysDismissedAnimation);
final ValueNotifier<_SearchBody?> _currentBodyNotifier = ValueNotifier<_SearchBody?>(null);
_SearchBody? get _currentBody => _currentBodyNotifier.value;
set _currentBody(_SearchBody? value) {
_currentBodyNotifier.value = value;
}
_SearchPageRoute<T>? _route;
}
/// Describes the body that is currently shown under the [AppBar] in the
/// search page.
enum _SearchBody {
/// Suggested queries are shown in the body.
///
/// The suggested queries are generated by [SearchDelegate.buildSuggestions].
suggestions,
/// Search results are currently shown in the body.
///
/// The search results are generated by [SearchDelegate.buildResults].
results,
}
class _SearchPageRoute<T> extends PageRoute<T> {
_SearchPageRoute({
required this.delegate,
}) {
assert(
delegate._route == null,
'The ${delegate.runtimeType} instance is currently used by another active '
'search. Please close that search by calling close() on the SearchDelegate '
'before opening another search with the same delegate instance.',
);
delegate._route = this;
}
final SearchDelegate<T> delegate;
@override
Color? get barrierColor => null;
@override
String? get barrierLabel => null;
@override
Duration get transitionDuration => const Duration(milliseconds: 300);
@override
bool get maintainState => false;
@override
Widget buildTransitions(
BuildContext context,
Animation<double> animation,
Animation<double> secondaryAnimation,
Widget child,
) {
return FadeTransition(
opacity: animation,
child: child,
);
}
@override
Animation<double> createAnimation() {
final Animation<double> animation = super.createAnimation();
delegate._proxyAnimation.parent = animation;
return animation;
}
@override
Widget buildPage(
BuildContext context,
Animation<double> animation,
Animation<double> secondaryAnimation,
) {
return _SearchPage<T>(
delegate: delegate,
animation: animation,
);
}
@override
void didComplete(T? result) {
super.didComplete(result);
assert(delegate._route == this);
delegate._route = null;
delegate._currentBody = null;
}
}
class _SearchPage<T> extends StatefulWidget {
const _SearchPage({
required this.delegate,
required this.animation,
});
final SearchDelegate<T> delegate;
final Animation<double> animation;
@override
State<StatefulWidget> createState() => _SearchPageState<T>();
}
class _SearchPageState<T> extends State<_SearchPage<T>> {
// This node is owned, but not hosted by, the search page. Hosting is done by
// the text field.
FocusNode focusNode = FocusNode();
@override
void initState() {
super.initState();
widget.delegate._queryTextController.addListener(_onQueryChanged);
widget.animation.addStatusListener(_onAnimationStatusChanged);
widget.delegate._currentBodyNotifier.addListener(_onSearchBodyChanged);
focusNode.addListener(_onFocusChanged);
widget.delegate._focusNode = focusNode;
}
@override
void dispose() {
super.dispose();
widget.delegate._queryTextController.removeListener(_onQueryChanged);
widget.animation.removeStatusListener(_onAnimationStatusChanged);
widget.delegate._currentBodyNotifier.removeListener(_onSearchBodyChanged);
widget.delegate._focusNode = null;
focusNode.dispose();
}
void _onAnimationStatusChanged(AnimationStatus status) {
if (status != AnimationStatus.completed) {
return;
}
widget.animation.removeStatusListener(_onAnimationStatusChanged);
if (widget.delegate._currentBody == _SearchBody.suggestions) {
focusNode.requestFocus();
}
}
@override
void didUpdateWidget(_SearchPage<T> oldWidget) {
super.didUpdateWidget(oldWidget);
if (widget.delegate != oldWidget.delegate) {
oldWidget.delegate._queryTextController.removeListener(_onQueryChanged);
widget.delegate._queryTextController.addListener(_onQueryChanged);
oldWidget.delegate._currentBodyNotifier.removeListener(_onSearchBodyChanged);
widget.delegate._currentBodyNotifier.addListener(_onSearchBodyChanged);
oldWidget.delegate._focusNode = null;
widget.delegate._focusNode = focusNode;
}
}
void _onFocusChanged() {
if (focusNode.hasFocus && widget.delegate._currentBody != _SearchBody.suggestions) {
widget.delegate.showSuggestions(context);
}
}
void _onQueryChanged() {
setState(() {
// rebuild ourselves because query changed.
});
}
void _onSearchBodyChanged() {
setState(() {
// rebuild ourselves because search body changed.
});
}
@override
Widget build(BuildContext context) {
assert(debugCheckHasMaterialLocalizations(context));
final ThemeData theme = widget.delegate.appBarTheme(context);
final String searchFieldLabel = widget.delegate.searchFieldLabel
?? MaterialLocalizations.of(context).searchFieldLabel;
Widget? body;
switch(widget.delegate._currentBody) {
case _SearchBody.suggestions:
body = KeyedSubtree(
key: const ValueKey<_SearchBody>(_SearchBody.suggestions),
child: widget.delegate.buildSuggestions(context),
);
break;
case _SearchBody.results:
body = KeyedSubtree(
key: const ValueKey<_SearchBody>(_SearchBody.results),
child: widget.delegate.buildResults(context),
);
break;
case null:
break;
}
late final String routeName;
switch (theme.platform) {
case TargetPlatform.iOS:
case TargetPlatform.macOS:
routeName = '';
break;
case TargetPlatform.android:
case TargetPlatform.fuchsia:
case TargetPlatform.linux:
case TargetPlatform.windows:
routeName = searchFieldLabel;
}
return Semantics(
explicitChildNodes: true,
scopesRoute: true,
namesRoute: true,
label: routeName,
child: Theme(
data: theme,
child: Scaffold(
appBar: AppBar(
leading: widget.delegate.buildLeading(context),
title: TextField(
controller: widget.delegate._queryTextController,
focusNode: focusNode,
style: widget.delegate.searchFieldStyle ?? theme.textTheme.titleLarge,
textInputAction: widget.delegate.textInputAction,
keyboardType: widget.delegate.keyboardType,
onSubmitted: (String _) {
widget.delegate.showResults(context);
},
decoration: InputDecoration(hintText: searchFieldLabel),
),
actions: widget.delegate.buildActions(context),
bottom: widget.delegate.buildBottom(context),
),
body: AnimatedSwitcher(
duration: const Duration(milliseconds: 300),
child: body,
),
),
),
);
}
}