Results for “Widget”

widget is an immutable description of part of the UI. Flutter turns the widget tree into a longer-lived element tree and a render tree; when

tests (package:test) for plain Dart logic, widget tests (flutter_test: testWidgets, WidgetTester, find, matchers) that build real widgets in a fast headless environment, and integration

declarative: the UI is a function of state, so instead of mutating widgets you change the data and let the affected widgets rebuild. Keep state that

frame than the ~16 ms budget allows. Keep build() cheap and scoped (const widgets, small StatefulWidgets, lazy lists), avoid saveLayer-triggering effects such as Opacity and clipping

AnimatedContainer, AnimatedOpacity or TweenAnimationBuilder a duration and a new target value, and the widget animates there on its own. Use an explicit AnimationController with Tweens and AnimatedBuilder

scrollable or text field that was given no limit (unbounded height/width), or a widget like Expanded placed under the wrong parent. The remaining classics, setState called during

platform's assistive technologies (TalkBack, VoiceOver, screen readers on web and desktop). Material widgets fill it in for you; you customize it with Semantics, MergeSemantics and ExcludeSemantics

keeps a stack of Route objects; Navigator.push adds a route built from a widget (usually via MaterialPageRoute) and Navigator.pop removes the top one, optionally handing a result

many models, json_serializable generates fromJson/toJson instead of hand-written code. A widget filling in an order form is the request; the postal service (http) carries

when all of them returned null. Form is a container that groups FormField widgets; FormState (reached through a GlobalKey ) can validate, save or reset all of them

child can be anything up to max. A widget cannot pick any size it likes and never knows its own screen position; both are decided