Call method from onPressed of an IconButton - flutter

Question

I have an IconButton and in the onPressed() method I want to call a void method that receives an incremental number as a parameter when the Button is clicked, then when obtaining this value it must call another void which calculates the days of weeks.
I have tested the function and if I put the values ​​in hard it does work, however when I put it in the widget it always returns the same value and does not change, no matter how much I put the setState method, I don't know how to increase said value.
Here I attach part of the code:
import 'package:intl/intl.dart';
import 'package:flutter/material.dart';
class ExampleScreen extends StatefulWidget {
final String? text1;
final String? text2;
final String? text3;
const ExampleScreen({Key? key,
this.text1,
this.text2,
this.text3}
) : super(key: key);
#override
State<ExampleScreen> createState() => _ExampleScreenState();
}
class _ExampleScreenState extends State<ExampleScreen> {
int counter = 1;
void increase(){
counter++;
setState(() {
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: Padding(
padding: const EdgeInsets.fromLTRB(10,0,0,0),
child: Center(
child: Row(
mainAxisAlignment: MainAxisAlignment.start,
children: <Widget>[
_calendar(widget.text1,widget.text2,widget.text3,counter)
],
),
//),
),
)
);
}
}
_calendar(text1,text2,text3, int counter) => Container(
width: 250,
height: 50,
margin: const EdgeInsets.fromLTRB(50,0,0,0),
alignment: Alignment.center,
child: Wrap(
children:[
Container(
height: 225,
width: 225,
child: Column(
children: [
const SizedBox(height: 10,),
Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
crossAxisAlignment: CrossAxisAlignment.start,
children: [
IconButton(
onPressed: () {
//When I call the function increase it tells me that the function is not declared
calculation_days(counter);
print('amount : $counter');
},
icon:const Icon(Icons.arrow_back_ios_new_outlined,size: 10)
),
const Text('Title',style: TextStyle(fontSize: 12)),
IconButton(
onPressed: () {},
icon:const Icon(Icons.arrow_forward_ios_outlined,size: 10)
),
],
),
]
),
),
]
)
);
void calculation_days(int week)
{
int firstday;
List<String> days;
List<String> daysxWeek;
days=findPreviousSaturdays1(count: week);
firstday= int.parse(days[week-1]);
daysxWeek=[firstday.toString()];
daysxWeek.add(firstday.toString());
}

Answer 1

since you declare it inside the StatefulWidget, not the State, you need to access it inside your onPressed method like this:
widget.increase()
IconButton(
onPressed: () {
widget.increase(); // call it like this.
},
icon:const Icon(Icons.arrow_back_ios_new_outlined,size: 10)
);
Another solution is that you can move your increase() from StatefulWidget to the State class, then you can use it by calling increase() instead of widget.increase().