flutter/examples/api/lib/widgets/shortcuts/shortcuts.0.dart

// 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.

// Template: dev/snippets/config/templates/stateful_widget_scaffold_center.tmpl
//
// Comment lines marked with "▼▼▼" and "▲▲▲" are used for authoring
// of samples, and may be ignored if you are just exploring the sample.

// Flutter code sample for Shortcuts
//
//***************************************************************************
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// Here, we will use the [Shortcuts] and [Actions] widgets to add and subtract
// from a counter. When the child widget has keyboard focus, and a user presses
// the keys that have been defined in [Shortcuts], the action that is bound
// to the appropriate [Intent] for the key is invoked.
//
// It also shows the use of a [CallbackAction] to avoid creating a new [Action]
// subclass.

//* ▲▲▲▲▲▲▲▲ description ▲▲▲▲▲▲▲▲ (do not modify or remove section marker)
//***************************************************************************

import 'package:flutter/material.dart';
//****************************************************************************
//* ▼▼▼▼▼▼▼▼ code-imports ▼▼▼▼▼▼▼▼ (do not modify or remove section marker)

import 'package:flutter/services.dart';

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//****************************************************************************

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

/// This is the main application widget.
class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  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: MyStatefulWidget(),
        ),
      ),
    );
  }
}

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class IncrementIntent extends Intent {
  const IncrementIntent();
}

class DecrementIntent extends Intent {
  const DecrementIntent();
}

//* ▲▲▲▲▲▲▲▲ code-preamble ▲▲▲▲▲▲▲▲ (do not modify or remove section marker)
//*****************************************************************************

/// This is the stateful widget that the main application instantiates.
class MyStatefulWidget extends StatefulWidget {
  const MyStatefulWidget({Key? key}) : super(key: key);

  @override
  State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
}

/// This is the private State class that goes with MyStatefulWidget.
class _MyStatefulWidgetState extends State<MyStatefulWidget> {
//********************************************************************
//* ▼▼▼▼▼▼▼▼ code ▼▼▼▼▼▼▼▼ (do not modify or remove section marker)

  int count = 0;

  @override
  Widget build(BuildContext context) {
    return Shortcuts(
      shortcuts: <ShortcutActivator, Intent>{
        LogicalKeySet(LogicalKeyboardKey.arrowUp): const IncrementIntent(),
        LogicalKeySet(LogicalKeyboardKey.arrowDown): const DecrementIntent(),
      },
      child: Actions(
        actions: <Type, Action<Intent>>{
          IncrementIntent: CallbackAction<IncrementIntent>(
            onInvoke: (IncrementIntent intent) => setState(() {
              count = count + 1;
            }),
          ),
          DecrementIntent: CallbackAction<DecrementIntent>(
            onInvoke: (DecrementIntent intent) => setState(() {
              count = count - 1;
            }),
          ),
        },
        child: Focus(
          autofocus: true,
          child: Column(
            children: <Widget>[
              const Text('Add to the counter by pressing the up arrow key'),
              const Text(
                  'Subtract from the counter by pressing the down arrow key'),
              Text('count: $count'),
            ],
          ),
        ),
      ),
    );
  }

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//********************************************************************

}