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33403bd28e
This extracts the sample code out from the API doc comments, and places them in separate files on disk, allowing running of the examples locally, testing them, and building of slightly larger examples.
94 lines
3.0 KiB
Dart
94 lines
3.0 KiB
Dart
// Copyright 2014 The Flutter Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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// Template: dev/snippets/config/templates/stateful_widget_material_ticker.tmpl
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//
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// Comment lines marked with "▼▼▼" and "▲▲▲" are used for authoring
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// of samples, and may be ignored if you are just exploring the sample.
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// Flutter code sample for AlignTransition
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//
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//***************************************************************************
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//* ▼▼▼▼▼▼▼▼ description ▼▼▼▼▼▼▼▼ (do not modify or remove section marker)
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// The following code implements the [AlignTransition] as seen in the video
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// above:
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//* ▲▲▲▲▲▲▲▲ description ▲▲▲▲▲▲▲▲ (do not modify or remove section marker)
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//***************************************************************************
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import 'package:flutter/material.dart';
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void main() => runApp(const MyApp());
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/// This is the main application widget.
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class MyApp extends StatelessWidget {
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const MyApp({Key? key}) : super(key: key);
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static const String _title = 'Flutter Code Sample';
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@override
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Widget build(BuildContext context) {
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return const MaterialApp(
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title: _title,
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home: MyStatefulWidget(),
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);
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}
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}
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/// This is the stateful widget that the main application instantiates.
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class MyStatefulWidget extends StatefulWidget {
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const MyStatefulWidget({Key? key}) : super(key: key);
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@override
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State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
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}
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/// This is the private State class that goes with MyStatefulWidget.
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/// AnimationControllers can be created with `vsync: this` because of TickerProviderStateMixin.
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class _MyStatefulWidgetState extends State<MyStatefulWidget>
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with TickerProviderStateMixin {
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//********************************************************************
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//* ▼▼▼▼▼▼▼▼ code ▼▼▼▼▼▼▼▼ (do not modify or remove section marker)
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// Using `late final` for [lazy initialization](https://dart.dev/null-safety/understanding-null-safety#lazy-initialization).
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late final AnimationController _controller = AnimationController(
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duration: const Duration(seconds: 2),
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vsync: this,
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)..repeat(reverse: true);
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late final Animation<AlignmentGeometry> _animation = Tween<AlignmentGeometry>(
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begin: Alignment.bottomLeft,
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end: Alignment.center,
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).animate(
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CurvedAnimation(
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parent: _controller,
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curve: Curves.decelerate,
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),
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);
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@override
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void dispose() {
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_controller.dispose();
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super.dispose();
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}
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@override
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Widget build(BuildContext context) {
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return Container(
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color: Colors.white,
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child: AlignTransition(
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alignment: _animation,
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child: const Padding(
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padding: EdgeInsets.all(8),
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child: FlutterLogo(size: 150.0),
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),
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),
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);
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}
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//* ▲▲▲▲▲▲▲▲ code ▲▲▲▲▲▲▲▲ (do not modify or remove section marker)
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//********************************************************************
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}
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