Results for “BuildContext”

through many layers gets tedious. InheritedWidget lets any descendant find a value through BuildContext; dependents are rebuilt when the inherited widget is replaced with one whose updateShouldNotify

need. After any await on navigation, check mounted (or context.mounted) before touching the BuildContext; the user may have left the screen meanwhile. The Navigator is a desk

created on every build. StatelessWidget: build() depends only on its constructor arguments and BuildContext. StatefulWidget creates a State object that survives rebuilds and holds mutable data. State

import 'package:flutter/material.dart'; class MainScreen extends StatelessWidget { const MainScreen({super.key}); @override Widget build(BuildContext context) { return Scaffold( appBar: AppBar(title: const Text('Main Screen')), body: GestureDetector( onTap

How to write a staggered animation in Flutter. A staggered animation consists

controller when the widget is disposed. myController.dispose(); super.dispose(); } @override Widget build(BuildContext context) { // Fill this out in the next step. } } 3. Display the current value

Learn about common layout widgets in Flutter. Learn how to build layouts

navigate to a new screen, access the Navigator through the route's BuildContext and call imperative methods such as push() or pop() : Because Navigator keeps a stack

handle to the location of a widget in the widget tree. widgets.BuildContext BuildContext Build Context class widgets

widgets.BuildContext.BuildContext.new BuildContext new Build Context.new constructor widgets

Provides non-leaking access to a BuildContext. widgets.DisposableBuildContext DisposableBuildContext Disposable Build Context class widgets

abstract Action subclass that adds an optional BuildContext to the isEnabled and invoke methods to be able to provide context to actions. widgets.ContextAction ContextAction Context Action class

Signature for the callback to BuildContext.visitChildElements. widgets.ElementVisitor ElementVisitor Element Visitor typedef widgets

Signature for the callback to BuildContext.visitAncestorElements. widgets.ConditionalElementVisitor ConditionalElementVisitor Conditional Element Visitor typedef widgets

callback that given a BuildContext finds a NavigatorState. widgets.NavigatorFinderCallback NavigatorFinderCallback Navigator Finder Callback typedef widgets

Creates an ImageConfiguration based on the given BuildContext (and optionally size). widgets.createLocalImageConfiguration createLocalImageConfiguration create Local Image Configuration function widgets

Creates an object that provides access to a BuildContext without leaking a State. widgets.DisposableBuildContext.DisposableBuildContext.new DisposableBuildContext new Disposable Build Context.new constructor widgets

builder that creates a RelativeRect to position a popup menu. Both BuildContext and BoxConstraints are from the PopupRoute that displays this menu. material.PopupMenuPositionBuilder PopupMenuPositionBuilder Popup Menu Position

signature of a method that provides a BuildContext and ScrollController for building a widget that may overflow the draggable Axis of the containing area. widgets.ScrollableWidgetBuilder ScrollableWidgetBuilder Scrollable

Creates an adaptive Color that changes its effective color based on the BuildContext given. The default effective color is color. cupertino.CupertinoDynamicColor.CupertinoDynamicColor.new CupertinoDynamicColor new Cupertino Dynamic Color.new constructor

Creates an adaptive Color that changes its effective color based on the given BuildContext's brightness (from MediaQueryData.platformBrightness or CupertinoThemeData.brightness). The default effective color is color. cupertino.CupertinoDynamicColor.CupertinoDynamicColor.withBrightness

Creates an adaptive Color that changes its effective color based on the given BuildContext's brightness (from MediaQueryData.platformBrightness or CupertinoThemeData.brightness) and accessibility contrast setting (MediaQueryData.highContrast). The default

BuildContext` parameter was added to `TextEditingController.buildTextSpan`. With the `BuildContext` available, users can access `InheritedWidgets` inside `buildTextSpan` to retrieve state required to style the text, or otherwise

account for separators. return itemIndex == -1 ? null : itemIndex * 2; }, itemBuilder: (BuildContext context, int index) { return ListTile( key: ValueKey (items[index]), title: Text(items[index]), ); }, separatorBuilder: (BuildContext

throw exceptions. ```dart import 'package:material_ui/material_ui.dart'; void main() { runApp( MaterialApp( builder: (BuildContext context, Widget child) { // Builds two parallel navigators. This throws // error because both of navigators

MyCustomScrollBehavior extends MaterialScrollBehavior { // Override behavior methods and getters like multitouchDragStrategy @override MultitouchDragStrategy getMultitouchDragStrategy(BuildContext context) => MultitouchDragStrategy.sumAllPointers; } // Set ScrollBehavior for an entire application. MaterialApp( scrollBehavior: MyCustomScrollBehavior(), // ... ); ``` ### Setting

SnackBar`s would be shown by calling on the `Scaffold` within the current `BuildContext`. By calling `Scaffold.of(context).showSnackBar`, the current `Scaffold` would animate a `SnackBar` into

them with `RadioGroup`. ### Case 1: trivial case Code before migration: ```dart Widget build(BuildContext context) { return Column( children: [ Radio ( value: 0, groupValue: _groupValue, onChanged: (int? value) { setState

dart final ScrollController controller = ScrollController(); Scrollbar( controller: controller, child: ListView.builder( controller: controller, itemBuilder: (BuildContext context, int index) { return Text('Item $index'); } ) ); ``` Code after migration: ```dart final ScrollController

static `window` property, application and library code that has access to a `BuildContext` should use `View.of` to look up the `FlutterView` the context is associated with. Some

with `overlayLocation` instead. ### Case 1: trivial case Code before migration: ```dart Widget build(BuildContext context) { return OverlayPortal.targetsRootOverlay( controller: myController, overlayChildBuilder: _myBuilder, child: myChild, ); } ``` Code after migration: ```dart

TheAction.key)` instance. Code before migration: ```dart class MyWidget extends StatelessWidget { // ... @override Widget build(BuildContext context) { return Shortcuts( shortcuts: <LogicalKeySet, Intent> { LogicalKeySet(LogicalKeyboardKey.enter): Intent(ActivateAction.key), }, child: Actions( actions

Trackpad gestures on most platforms now send `PointerPanZoom` sequences and can trigger

Removed `MouseTracker`'s methods `attachAnnotation`, `detachAnnotation`, and `isAnnotationAttached`. The `MouseTracker` class has

constraints) { return Row( children: [ SizedBox( height: constraints.maxHeight, width: constraints.maxWidth / 2, child: ListView.builder( itemBuilder: (BuildContext context, int index) { return Text

widget Code before migration: ```dart final ScrollController controller = ScrollController(); ListView.builder( controller: controller, itemBuilder: (BuildContext context, int index) { return Text('Item $inde

material_ui/material_ui.dart'; void main() => runApp(Foo()); class Foo extends StatelessWidget { @override Widget build(BuildContext context) { return MediaQuery( data: const MediaQueryData(), child: Directionality( textDirection: TextDirection.ltr, child: Material( child

semantics tree. class _IgnorePointerWithSemantics extends SingleChildRenderObjectWidget { const _IgnorePointerWithSemantics({ super.child, }); @override _RenderIgnorePointerWithSemantics createRenderObject(BuildContext context) { return _Rende

cupertino_ui/cupertino_ui.dart'; void main() => runApp(Foo()); class Foo extends StatelessWidget { @override Widget build(BuildContext context) { return MediaQuery( data: const MediaQueryData(), child: CupertinoTabBar( items: const [ BottomNavigationBarItem( icon: Icon

final String? fontFamily; @override final String? fontPackage; @override final bool matchTextDirection; } Widget build(BuildContext context) { // Example usage of AppIcons: return Icon(AppIcons.arrowUpward); } ``` To maintain dot shorthand support

migration: ```dart class _MyWidgetState extends State { final ExpansionTileController controller = ExpansionTileController(); @override Widget build(BuildContext context) { return ExpansionTile( controller: controller, ); } } ``` Code after migration: ```dart class _MyWidgetState extends State

hood. No migration is needed: ```dart class _MyWidgetState extends State { @override Widget build(BuildContext context) { TextField( contextMenuBuilder: (BuildContext context, EditableTextState editableTextState) { return SystemContextMenu.editableText( editableTextState: editableTextState

changes. Code before migration: ```dart class MyWidget extends StatelessWidget { @override Widget build(BuildContext context) { return FormField( autovalidate: true, builder: (FormFieldState state) { return Container(); }, ); } } ``` Code after migration: ```dart

material_ui/material_ui.dart'; void main() => runApp(Foo()); class Foo extends StatelessWidget { @override Widget build(BuildContext context) { return MaterialApp( home: Scaffold( floatingActionButton: FloatingActionButton(onPressed: () { showDialog( context: context, builder: (BuildContext

migration: ```dart class FooState extends State { String buttonLabel = 'Click Me'; @override Widget build(BuildContext context) { return ElevatedButton( onPressed: () async { // Illegal state modification that should

using static member functions that are typically called `of`, and take a `BuildContext`. In order to modify your code to use the new form of the APIs

For some time now (years), Flutter has had two key event systems

For some time now (years), Flutter has had two key event systems

The Material and Cupertino design libraries are now available as standalone packages

tree in your test: ```dart Directionality( textDirection: TextDirection.ltr, child: Overlay( initialEntries: [ OverlayEntry( builder: (BuildContext context) { return ListView( children: [ const Text('before'), Tooltip( key: tooltipKey, showDuration: const Duration

Context menus, or text selection toolbars, are the menus that show up