一个 Flutter 包，通过灵活的声明式 API 简化了流程。

flow_builder

Flutter 流程轻松搞定！一个 Flutter 包，通过灵活的声明式 API 简化了流程。

用法

定义一个流程状态

流程状态将是驱动流程的状态。每次此状态更改时，都将根据新的流程状态生成一个新的导航堆栈。

class Profile {
  const Profile({this.name, this.age, this.weight});

  final String? name;
  final int? age;
  final int? weight;

  Profile copyWith({String? name, int? age, int? weight}) {
    return Profile(
      name: name ?? this.name,
      age: age ?? this.age,
      weight: weight ?? this.weight,
    );
  }
}

创建一个 FlowBuilder

FlowBuilder 是一个响应流程状态更改来构建导航堆栈的 widget。onGeneratePages 将为每个状态更改调用，并且必须将新的导航堆栈作为页面列表返回。

FlowBuilder<Profile>(
  state: const Profile(),
  onGeneratePages: (profile, pages) {
    return [
      MaterialPage(child: NameForm()),
      if (profile.name != null) MaterialPage(child: AgeForm()),
    ];
  },
);

更新流程状态

可以通过 context.flow<T>().update 更新流程状态。

class NameForm extends StatefulWidget {
  @override
  _NameFormState createState() => _NameFormState();
}

class _NameFormState extends State<NameForm> {
  var _name = '';

  void _continuePressed() {
    context.flow<Profile>().update((profile) => profile.copyWith(name: _name));
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Name')),
      body: Center(
        child: Column(
          children: <Widget>[
            TextField(
              onChanged: (value) => setState(() => _name = value),
              decoration: InputDecoration(
                labelText: 'Name',
                hintText: 'John Doe',
              ),
            ),
            RaisedButton(
              child: const Text('Continue'),
              onPressed: _name.isNotEmpty ? _continuePressed : null,
            )
          ],
        ),
      ),
    );
  }
}

完成流程

可以通过 context.flow<T>().complete 完成流程。

class AgeForm extends StatefulWidget {
  @override
  _AgeFormState createState() => _AgeFormState();
}

class _AgeFormState extends State<AgeForm> {
  int? _age;

  void _continuePressed() {
    context
        .flow<Profile>()
        .complete((profile) => profile.copyWith(age: _age));
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Age')),
      body: Center(
        child: Column(
          children: <Widget>[
            TextField(
              onChanged: (value) => setState(() => _age = int.parse(value)),
              decoration: InputDecoration(
                labelText: 'Age',
                hintText: '42',
              ),
              keyboardType: TextInputType.number,
            ),
            RaisedButton(
              child: const Text('Continue'),
              onPressed: _age != null ? _continuePressed : null,
            )
          ],
        ),
      ),
    );
  }
}

FlowController

FlowBuilder 也可以通过自定义 FlowController 创建，以防流程可以在子树之外进行操作。

class MyFlow extends StatefulWidget {
  @override
  State<MyFlow> createState() => _MyFlowState();
}

class _MyFlowState extends State<MyFlow> {
  late FlowController<Profile> _controller;

  @override
  void initState() {
    super.initState();
    _controller = FlowController(const Profile());
  }

  @override
  Widget build(BuildContext context) {
    return FlowBuilder(
      controller: _controller,
      onGeneratePages: ...,
    );
  }

  @override dispose() {
    _controller.dispose();
    super.dispose();
  }
}

GitHub

https://github.com/felangel/flow_builder