Flutter - click one RaisedButton and all RaisedButtons update - flutter

Question

I am working on a calculator type app that has a lot of buttons on the screen. When I turn on dev tools to check repainting, I noticed that whenever one button is clicked, every button on the screen repaints. Instead of pasting tons of code in here, I created a demo app that shows what it is that I am doing. This is what the screen looks like:
Whenever any of the buttons are pressed, every button on the screen redraws.
This is the code that I'm using:
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Button Testing'),
),
body: Center(
child: Padding(
padding: const EdgeInsets.all(8.0),
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.stretch,
children: <Widget>[
Text(
buttonPressed,
textAlign: TextAlign.center,
),
SizedBox(
height: 10.0,
),
RaisedButton(
child: Text('Button One'),
onPressed: () {
setState(() {
buttonPressed = 'Button One Was Pressed';
});
},
),
RaisedButton(
child: Text('Button Two'),
onPressed: () {
setState(() {
buttonPressed = 'Button Two Was Pressed';
});
},
),
RaisedButton(
child: Text('Button Three'),
onPressed: () {
setState(() {
buttonPressed = 'Button Three Was Pressed';
});
},
),
RaisedButton(
child: Text('Button Four'),
onPressed: () {
setState(() {
buttonPressed = 'Button Four Was Pressed';
});
},
),
],
),
),
),
);
}
I've tried breaking the button area out into a separate widget and nothing I've done matters. My question is, is there something else that I should be doing? Is this expected and acceptable behavior? Does it even matter that everything is redrawing whenever any buttons are tapped? I thought that in Flutter, only the things that needed to be redrawn were redrawn.

Answer 1

Whenever you call setState then it rebuild whole build method, so it is obvious that it rebuild RaisedButton.
You can avoid by using provider, Bloc and so on which will not rebuild whole build method. It will only change data.
It is totally depends on you that you want to accept it or not. If widget is not that much big than you can keep it according to me.
Redrawing widget every time is really not good practice but if it is not rebuilding very frequently or your application is not that much big then it is fine.

Answer 2

setState will rebuild all the screen ,
So you can avoid that by using Bloc it is a state controller which won't rebuild everything only what you need to rebuild you can use it from scratch or use the plugin bloc 1.0.0