how to make custom widget like cart counter for reusable widget in flutter?

IMemon
January 31, 2024
261 views
3 votes
3 Answers

I am given task for creating counter widget which has two iconbutton for increment and decrement value..

increment by 1 and decrement by -1, no variation..its fix..

I have created design but dont know how to implement it with – and + functionality

can anyone suggest me how to solve it


class _HomeScreenState extends State<HomeScreen> {
  int age=30;
  int weight=39;
  int score=100;

  @override
  Widget build(BuildContext context) {
    return  Scaffold(
      body: Column(children: [
        const SizedBox(height: 100,),
        CartCounter(value: age,),
        const SizedBox(height: 100,),
        CartCounter(value: weight,),
        const SizedBox(height: 100,),
        CartCounter(value: score,),
      ],),
    );
  }
}

here is my effort but dont know how to implement increment coding and decrement coding


class CartCounter extends StatefulWidget {
  final int value;

  const CartCounter({Key? key,required this.value}) : super(key: key);

  @override
  State<CartCounter> createState() => _CartCounterState();
}

class _CartCounterState extends State<CartCounter> {
  @override
  Widget build(BuildContext context) {
    return Container(
      height: 80,
      width: 200,
      decoration: BoxDecoration(

          borderRadius: BorderRadius.circular(20)
      ),
      child: Row(
        mainAxisAlignment: MainAxisAlignment.spaceAround,
        children: [
        IconButton(
            color: Colors.blue,
            onPressed: (){


            }, icon: Icon(Icons.remove)),
        SizedBox(width: 60,child: Center(child: Text(widget.value.toString(),style: Theme.of(context).textTheme.headlineSmall,)),),
        IconButton(
            color: Colors.blue,
            onPressed: (){}, icon: Icon(Icons.add)),

      ],),
    );
  }
}

Tags: flutter

Answers

If I correctly understood your question, you want to implement the onPressed-Method in the IconButtons.

Here is my updated code:

child: Row(
  mainAxisAlignment: MainAxisAlignment.spaceAround,
  children: [
    IconButton(
      color: Colors.blue,
      onPressed: () {
        setState(() {
          if (widget.value > 0) {
            widget.value--;
          }
        });
      },
      icon: Icon(Icons.remove),
    ),
    SizedBox(
      width: 60,
      child: Center(
        child: Text(
          widget.value.toString(),
          style: Theme.of(context).textTheme.headlineSmall,
        ),
      ),
    ),
    IconButton(
      color: Colors.blue,
      onPressed: () {
        setState(() {
          widget.value++;
        });
      },
      icon: Icon(Icons.add),
    ),
  ],
),

I hope I helped you 😉

here is the solution…try..it will work

u just missing to add a Function in ur custom widget and returning value to calling class

add this Function to your custom widget and this widget should be stateful widget
final Function(int) onChange;

I have used a local variable named result and do increment and decrement it while tapping on iconbutton..

import 'package:flutter/material.dart';

class CartCounter extends StatefulWidget {
  final int value;
  final Function(int) onChange;
  const CartCounter({Key? key,required this.value,required this.onChange}) : super(key: key);

  @override
  State<CartCounter> createState() => _CartCounterState();
}

class _CartCounterState extends State<CartCounter> {
late int result;


@override
  void initState() {
    // TODO: implement initState
    super.initState();
    result=widget.value;
  }

  @override
  Widget build(BuildContext context) {
    return Container(
      height: 80,
      width: 200,
      decoration: BoxDecoration(

          borderRadius: BorderRadius.circular(20)
      ),
      child: Row(
        mainAxisAlignment: MainAxisAlignment.spaceAround,
        children: [
        IconButton(
            color: Colors.blue,
            onPressed: (){
              setState(() {
                result--;
                widget.onChange(result); // for returning value
              });


            }, icon: Icon(Icons.remove)),
        SizedBox(width: 60,child: Center(child: Text(result.toString(),style: Theme.of(context).textTheme.headlineSmall,)),),
        IconButton(
            color: Colors.blue,
            onPressed: (){
              setState(() {
                result++;
                widget.onChange(result);// for return value 
              });
            }, icon: Icon(Icons.add)),

      ],),
    );
  }
}

Here, I have give the code: 

Create a new CartCounter class that extends StatefulWidget. This is because we need to keep track of the count.

import 'package:flutter/material.dart';

class CartCounter extends StatefulWidget {
  final int initialValue;
  final VoidCallback onPressed;

  CartCounter({required this.initialValue, required this.onPressed});

  @override
  _CartCounterState createState() => _CartCounterState();
}

class _CartCounterState extends State<CartCounter> {
  int count = 0;

  @override
  void initState() {
    super.initState();
    count = widget.initialValue;
  }

  @override
  Widget build(BuildContext context) {
    return Row(
      children: [
        buildOutlineButton(Icons.remove, () {
          if (count > 0) {
            count--;
            widget.onPressed();
          }
        }),
        Padding(
          padding: const EdgeInsets.symmetric(horizontal: 8.0),
          child: Text(
            count.toString(),
            style: TextStyle(fontSize: 20),
          ),
        ),
        buildOutlineButton(Icons.add, widget.onPressed),
      ],
    );
  }

  OutlinedButton buildOutlineButton(IconData icon, Function onPressed) {
    return OutlinedButton(
      onPressed: onPressed as void Function()?,
      style: OutlinedButton.styleFrom(
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(10),
        ),
        padding: EdgeInsets.zero,
      ),
      child: Icon(icon),
    );
  }
}

Now use like this as a reusable widget:

CartCounter(
  initialValue: 0,
  onPressed: () {},
),

Hope you found the answer.....

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