ordered_traversal_policy.0.dart 2.3 KB
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// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

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// Flutter code sample for [OrderedTraversalPolicy].
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import 'package:flutter/material.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
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  const MyApp({super.key});
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  static const String _title = 'Flutter Code Sample';

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: _title,
      home: Scaffold(
        appBar: AppBar(title: const Text(_title)),
        body: const Center(
          child: MyStatelessWidget(),
        ),
      ),
    );
  }
}

class DemoButton extends StatelessWidget {
  const DemoButton({
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    super.key,
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    required this.name,
    this.autofocus = false,
    required this.order,
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  });
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  final String name;
  final bool autofocus;
  final double order;

  void _handleOnPressed() {
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    debugPrint('Button $name pressed.');
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    debugDumpFocusTree();
  }

  @override
  Widget build(BuildContext context) {
    return FocusTraversalOrder(
      order: NumericFocusOrder(order),
      child: TextButton(
        autofocus: autofocus,
        onPressed: () => _handleOnPressed(),
        child: Text(name),
      ),
    );
  }
}

class MyStatelessWidget extends StatelessWidget {
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  const MyStatelessWidget({super.key});
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  @override
  Widget build(BuildContext context) {
    return FocusTraversalGroup(
      policy: OrderedTraversalPolicy(),
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      child: const Column(
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        mainAxisAlignment: MainAxisAlignment.center,
        children: <Widget>[
          Row(
            mainAxisAlignment: MainAxisAlignment.center,
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            children: <Widget>[
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              DemoButton(name: 'Six', order: 6),
            ],
          ),
          Row(
            mainAxisAlignment: MainAxisAlignment.center,
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            children: <Widget>[
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              DemoButton(name: 'Five', order: 5),
              DemoButton(name: 'Four', order: 4),
            ],
          ),
          Row(
            mainAxisAlignment: MainAxisAlignment.center,
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            children: <Widget>[
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              DemoButton(name: 'Three', order: 3),
              DemoButton(name: 'Two', order: 2),
              DemoButton(name: 'One', order: 1, autofocus: true),
            ],
          ),
        ],
      ),
    );
  }
}