Setstate not working when adding a widget to the background? [SOLVED] - flutter

Question

The widget I made for the background color is causing a problem.
There is a problem when a child widget is added to the Background Color widget I made. In this case setstate doesn't work.
Setstate not working when adding a widget to the background?
Why is the screen not updating?
Why do you think this is not happening? Where am I doing wrong?
//zemin_rengi.dart
import 'package:flutter/material.dart';
class ZeminRengi extends StatefulWidget {
final Widget childWidget;
const ZeminRengi({required this.childWidget});
#override
State<ZeminRengi> createState() => _ZeminRengiState();
}
class _ZeminRengiState extends State<ZeminRengi> {
Widget? _childWidget;
#override
void initState() {
// TODO: implement initState
super.initState();
_childWidget = widget.childWidget;
}
#override
Widget build(BuildContext context) {
return Container(
width: MediaQuery.of(context).size.width,
height: MediaQuery.of(context).size.height,
decoration: const BoxDecoration(
gradient: LinearGradient(
begin: Alignment.topCenter,
end: Alignment.bottomCenter,
colors: [Colors.blue, Colors.red]),
),
child: _childWidget,
);
}
}
//main.dart
import 'package:builk/zemin_rengi.dart';
import 'package:flutter/material.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({super.key});
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: const MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
const MyHomePage({super.key, required this.title});
final String title;
#override
State<MyHomePage> createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int _counter = 0;
void _incrementCounter() {
setState(() {
_counter++;
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: ZeminRengi(
childWidget: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
const Text(
'You have pushed the button this many times:',
),
Text(
'$_counter',
style: Theme.of(context).textTheme.headline4,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: const Icon(Icons.add),
),
);
}
}
thanks for help.
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