ObservableBuilder<T> class

请叫我code哥

//*****************************************************
// use the example:
// 使用示例
//*****************************************************
class CounterState {
  int counter = 0;
}

var observableCounter = Observable(CounterState());

class TestWidget extends StatefulWidget {
  @override
  _TestWidgetState createState() => _TestWidgetState();
}

class _TestWidgetState extends State<TestWidget> {
  @override
  void initState() {
    observableCounter.listen((state) {
      print(state.counter);
    });
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        ObservableBuilder<CounterState>(
          create: observableCounter,
          memo: (state) => [state.counter],
          builder: (context, state) {
            return Text('${state.counter}');
          },
        ),
        IconButton(
          onPressed: () => observableCounter.notify((state) => state.counter++),
          icon: Icon(Icons.add),
        )
      ],
    );
  }
}
//*****************************************************
// provide a solution to change the theme
// 提供一种改变主题的解决方案
// change the theme example:
// 使用示例
//*****************************************************
enum ThemeType {
  dark,
  light,
}

class ThemeState {
  ThemeType type = ThemeType.dark;

  Color get title =>
      {ThemeType.dark: Colors.white, ThemeType.light: Color(0xff3c3f41)}[type]!;

  Color get body =>
      {ThemeType.dark: Color(0xff3c3f41), ThemeType.light: Colors.white}[type]!;
}

var observableTheme = Observable(ThemeState());
// change the theme：
observableTheme.notify((theme) => theme.type =
    theme.type == ThemeType.light
        ? ThemeType.dark
        : ThemeType.light);

class ThemeBuilder extends StatelessWidget {
  const ThemeBuilder({
    Key? key,
    required this.builder,
  }) : super(key: key);

  final Widget Function(BuildContext, ThemeState) builder;

  @override
  Widget build(BuildContext context) => ObservableBuilder<ThemeState>(
      create: observableTheme, memo: (theme) => [theme.type], builder: builder);
}

Inheritance

Constructors

ObservableBuilder({Key? key, required Observable<T> create, _Memo<T>? memo, required _Builder<T> builder}): 默认builder函数不会跟随父组件rebuild，只会监听数据变化触发rebuild。当builder函数使用了其它状态otherState(非回调参数state)，通过给ObservableBuilder设置ValueKey(otherState)，使其触发rebuild。 StatelessWidget引用其它状态otherState需要设置key，使其触发rebuild。 StatefulWidget通过参数传递其它状态otherState不需要设置key，参数变化会触发rebuild。
const

Properties

builder → _Builder<T>: final
create → Observable<T>: final
hashCode → int: The hash code for this object.
no setterinherited
key → Key?: Controls how one widget replaces another widget in the tree.
finalinherited
memo → _Memo<T>?: final
runtimeType → Type: A representation of the runtime type of the object.
no setterinherited

Methods

build(BuildContext context) → Widget: Describes the part of the user interface represented by this widget.
override
createElement() → StatelessElement: Creates a StatelessElement to manage this widget's location in the tree.
inherited
debugDescribeChildren() → List<DiagnosticsNode>: Returns a list of DiagnosticsNode objects describing this node's children.
inherited
debugFillProperties(DiagnosticPropertiesBuilder properties) → void: Add additional properties associated with the node.
inherited
noSuchMethod(Invocation invocation) → dynamic: Invoked when a nonexistent method or property is accessed.
inherited
toDiagnosticsNode({String? name, DiagnosticsTreeStyle? style}) → DiagnosticsNode: Returns a debug representation of the object that is used by debugging tools and by DiagnosticsNode.toStringDeep.
inherited
toString({DiagnosticLevel minLevel = DiagnosticLevel.info}) → String: A string representation of this object.
inherited
toStringDeep({String prefixLineOne = '', String? prefixOtherLines, DiagnosticLevel minLevel = DiagnosticLevel.debug}) → String: Returns a string representation of this node and its descendants.
inherited
toStringShallow({String joiner = ', ', DiagnosticLevel minLevel = DiagnosticLevel.debug}) → String: Returns a one-line detailed description of the object.
inherited
toStringShort() → String: A short, textual description of this widget.
inherited

Operators

operator ==(Object other) → bool: The equality operator.
inherited

ObservableBuilder<T> class

Constructors

Properties

Methods

Operators

observable library