didChangeDependencies什么时候被调用

参考
我先上一个Demo，这个Demo也就是网上面传的比较广的，我们就以这个来举例子说明网上的结论：“父级结构中的层级发生变化时didChangeDependencies被调用“ 这个结论为什么是不完整

import 'package:flutter/material.dart';

class TestDidChangeDependencies2 extends StatefulWidget {
  @override
  State<StatefulWidget> createState() => TestDidChangeDependencies2State();
}

class TestDidChangeDependencies2State extends State<TestDidChangeDependencies2> {
  bool bDependenciesShouldChange = true;

  @override
  void initState() {
    super.initState();
  }

  @override
  Widget build(BuildContext context) {

    return Scaffold(
        body: bDependenciesShouldChange ?
            Container(
              height: 500,
              alignment: Alignment.centerLeft,
              child: C(child: B()),
            )
            : Container(
              height: 500,
              alignment: Alignment.centerLeft,
              child: C(child: SizedBox(width: 20, height: 50, child: B())),
          ),
          floatingActionButton: FloatingActionButton(
            onPressed: _incrementCounter,
            tooltip: 'Increment',
            child: Icon(Icons.add),
          )
    );
  }

  void _incrementCounter(){
    setState(() {
      bDependenciesShouldChange = !bDependenciesShouldChange;
    });
  }

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    debugPrint("AdidChangeDependencies");
  }
}

class B extends StatefulWidget {
  @override
  State<StatefulWidget> createState() => BState();
}

class BState extends State<B> {
  @override
  Widget build(BuildContext context) {
    return Center(child: Text("Test"));
  }

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    debugPrint("BdidChangeDependencies");
  }
}

class C extends StatefulWidget {
  final Widget child;

  C({Key? key, required this.child}) : super(key: key);

  @override
  State<StatefulWidget> createState() => CState();
}

class CState extends State<C> {
  @override
  Widget build(BuildContext context) {
    return widget.child;
  }

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    debugPrint("CdidChangeDependencies");
  }
}

class D extends StatelessWidget{

  final Widget child_D;
  D({required this.child_D});

  @override
  Widget build(BuildContext context) {
    return child_D;
  }
}

这个是网上流传的Demo，我把它调试为比较好可运行状态，大家可以来观察下输出，首先刚运行的时候就会打印如下：

I/flutter (20121): AdidChangeDependencies
I/flutter (20121): CdidChangeDependencies
I/flutter (20121): BdidChangeDependencies