flutter_should_build

Sumarry

• this is a way of resolving the issue of rebuilding stateful widget when a navigator is pushing or popping

• associated issue：flutter/flutter#11655

Usage

1. import XCShouldBuild.dart and XCState.dart

2. make all classes of State inherit from [XCState]，do not inherit from [State]

3. override [XCState.shouldBuild]，do not override [State.build]

4. use [XCState.reload] to reload，do not use [State.setState] to reload

Code

• scene 1：

override [XCState.shouldBuild], it can avoid rebuilding when pushing or popping.

class _XCTestViewState extends XCState {

  @override
  Widget shouldBuild(BuildContext context) {
    return Center(
        child: Text(
            "_XCTestView, if you use `shouldBuild`, it can avoid rebuilding when pushing or popping"));
  }
    
  void aFunc() {
    reload()
  }

}

• scene 2

override [XCState.useSubstance] and [XCState.substance], decide for yourself whether or not to rebuild when pushing or popping.

class _XCUseSubstanceTestViewState extends XCState {

  var _aCountAsSubstance = 0;

  @override
  Widget shouldBuild(BuildContext context) {
    return Center(
        child: Text(
            "_XCUseSubstanceTestView, if you use `shouldBuild`, it can avoid rebuilding when pushing or popping, _aCountAsSubstance = $_aCountAsSubstance "));
  }

  /// only effect to pushing or poping, no effect to [XCState.reload]
  @override
  bool useSubstance() {
    return true;
  }

  /// only effect to pushing or poping, no effect to [XCState.reload]
  @override
  substance() {
    return _aCountAsSubstance;
  }

  void aFunc() {
    reload();
  }
}