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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.
// Flutter code sample for [Actions].
import 'package:flutter/material.dart';
void main() => runApp(const MyApp());
class MyApp extends StatelessWidget {
const MyApp({super.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(),
),
),
);
}
}
// A simple model class that notifies listeners when it changes.
class Model {
ValueNotifier<bool> isDirty = ValueNotifier<bool>(false);
ValueNotifier<int> data = ValueNotifier<int>(0);
int save() {
if (isDirty.value) {
debugPrint('Saved Data: ${data.value}');
isDirty.value = false;
}
return data.value;
}
void setValue(int newValue) {
isDirty.value = data.value != newValue;
data.value = newValue;
}
}
class ModifyIntent extends Intent {
const ModifyIntent(this.value);
final int value;
}
// An Action that modifies the model by setting it to the value that it gets
// from the Intent passed to it when invoked.
class ModifyAction extends Action<ModifyIntent> {
ModifyAction(this.model);
final Model model;
@override
void invoke(covariant ModifyIntent intent) {
model.setValue(intent.value);
}
}
// An intent for saving data.
class SaveIntent extends Intent {
const SaveIntent();
}
// An Action that saves the data in the model it is created with.
class SaveAction extends Action<SaveIntent> {
SaveAction(this.model);
final Model model;
@override
int invoke(covariant SaveIntent intent) => model.save();
}
class SaveButton extends StatefulWidget {
const SaveButton(this.valueNotifier, {super.key});
final ValueNotifier<bool> valueNotifier;
@override
State<SaveButton> createState() => _SaveButtonState();
}
class _SaveButtonState extends State<SaveButton> {
int savedValue = 0;
@override
Widget build(BuildContext context) {
return AnimatedBuilder(
animation: widget.valueNotifier,
builder: (BuildContext context, Widget? child) {
return TextButton.icon(
icon: const Icon(Icons.save),
label: Text('$savedValue'),
style: ButtonStyle(
foregroundColor: MaterialStatePropertyAll<Color>(
widget.valueNotifier.value ? Colors.red : Colors.green,
),
),
onPressed: () {
setState(() {
savedValue = Actions.invoke(context, const SaveIntent())! as int;
});
},
);
},
);
}
}
class MyStatefulWidget extends StatefulWidget {
const MyStatefulWidget({super.key});
@override
State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
}
class _MyStatefulWidgetState extends State<MyStatefulWidget> {
Model model = Model();
int count = 0;
@override
Widget build(BuildContext context) {
return Actions(
actions: <Type, Action<Intent>>{
ModifyIntent: ModifyAction(model),
SaveIntent: SaveAction(model),
},
child: Builder(
builder: (BuildContext context) {
return Row(
mainAxisAlignment: MainAxisAlignment.spaceAround,
children: <Widget>[
const Spacer(),
Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
IconButton(
icon: const Icon(Icons.exposure_plus_1),
onPressed: () {
Actions.invoke(context, ModifyIntent(++count));
},
),
AnimatedBuilder(
animation: model.data,
builder: (BuildContext context, Widget? child) {
return Padding(
padding: const EdgeInsets.all(8.0),
child: Text('${model.data.value}',
style: Theme.of(context).textTheme.headlineMedium),
);
}),
IconButton(
icon: const Icon(Icons.exposure_minus_1),
onPressed: () {
Actions.invoke(context, ModifyIntent(--count));
},
),
],
),
SaveButton(model.isDirty),
const Spacer(),
],
);
},
),
);
}
}