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.
116 lines
3.4 KiB
Dart
116 lines
3.4 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.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 Focus
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//
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//***************************************************************************
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//* ▼▼▼▼▼▼▼▼ description ▼▼▼▼▼▼▼▼ (do not modify or remove section marker)
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// This example shows how to focus a newly-created widget immediately after it
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// is created.
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//
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// The focus node will not actually be given the focus until after the frame in
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// which it has requested focus is drawn, so it is OK to call
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// [FocusNode.requestFocus] on a node which is not yet in the focus tree.
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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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class _MyStatefulWidgetState extends State<MyStatefulWidget> {
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//********************************************************************
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//* ▼▼▼▼▼▼▼▼ code ▼▼▼▼▼▼▼▼ (do not modify or remove section marker)
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int focusedChild = 0;
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List<Widget> children = <Widget>[];
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List<FocusNode> childFocusNodes = <FocusNode>[];
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@override
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void initState() {
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super.initState();
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// Add the first child.
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_addChild();
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}
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@override
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void dispose() {
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super.dispose();
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for (final FocusNode node in childFocusNodes) {
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node.dispose();
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}
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}
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void _addChild() {
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// Calling requestFocus here creates a deferred request for focus, since the
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// node is not yet part of the focus tree.
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childFocusNodes
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.add(FocusNode(debugLabel: 'Child ${children.length}')..requestFocus());
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children.add(Padding(
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padding: const EdgeInsets.all(2.0),
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child: ActionChip(
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focusNode: childFocusNodes.last,
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label: Text('CHILD ${children.length}'),
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onPressed: () {},
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),
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));
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}
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@override
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Widget build(BuildContext context) {
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return Scaffold(
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body: Center(
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child: Wrap(
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children: children,
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),
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),
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floatingActionButton: FloatingActionButton(
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onPressed: () {
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setState(() {
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focusedChild = children.length;
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_addChild();
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});
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},
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child: const Icon(Icons.add),
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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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