Transitions
sample.packages.flutter.lib.src.widgets.transitions.28.
This code defines a widget called Spinner
that spins a green square
continually. It is built with an [AnimatedWidget].
import 'dart:math' as math;
import 'package:flutter/material.dart';
void main() => runApp(const MyApp());
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
static const String _title = 'Flutter Code Sample';
@override
Widget build(BuildContext context) {
return const MaterialApp(
title: _title,
home: MyStatefulWidget(),
);
}
}
class SpinningContainer extends AnimatedWidget {
const SpinningContainer({
Key? key,
required AnimationController controller,
}) : super(key: key, listenable: controller);
Animation get _progress => listenable as Animation;
@override
Widget build(BuildContext context) {
return Transform.rotate(
angle: _progress.value * 2.0 * math.pi,
child: Container(width: 200.0, height: 200.0, color: Colors.green),
);
}
}
class MyStatefulWidget extends StatefulWidget {
const MyStatefulWidget({Key? key}) : super(key: key);
@override
State createState() => _MyStatefulWidgetState();
}
/// AnimationControllers can be created with `vsync: this` because of TickerProviderStateMixin.
class _MyStatefulWidgetState extends State
with TickerProviderStateMixin {
late final AnimationController _controller = AnimationController(
duration: const Duration(seconds: 10),
vsync: this,
)..repeat();
@override
void dispose() {
_controller.dispose();
super.dispose();
}
@override
Widget build(BuildContext context) {
return SpinningContainer(controller: _controller);
}
}
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