Why am I having memory issues with flutter ChangeNotifierProvider? - flutter

Question

I am making a shopping cart app in flutter with Change Notifier Provider. It is working fast and well at first. But it takes the more memory, the more I use it. I am adding and removing clearing items from list. Nothing complicated. Cannot know why it is working like this. It is slowing down gradually. This is main.dart:
class Main extends StatelessWidget {
#override
Widget build(BuildContext context) {
return ChangeNotifierProvider(
create: (context) => Cart(),
child: MaterialApp(
title: 'Flutter Demo',
debugShowCheckedModeBanner: false,
theme: ThemeData(
primarySwatch: swatchColor,
primaryColor: primaryColor,
accentColor: tertiaryColor,
textSelectionTheme: TextSelectionThemeData(
cursorColor: Colors.black,
selectionColor: primaryColor,
selectionHandleColor: primaryColor,
),
),
initialRoute: '/login',
routes: {
'/home': (context) => Home(),
'/login': (context) => Login(),
'/tableReview': (context) => TableReview(),
'/createOrder': (context) => CreateOrder(),
'/orderReview': (context) => OrderReview(),
},
),
);
}
}
This is main cart_model.dart
import 'package:counter/data/models/cart_item.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/foundation.dart';
class Cart extends ChangeNotifier {
List<Item> cart = [];
addItemToCart({#required item}) {
Item newItem = Item(
id: item.id,
price: item.price is int ? item.price : int.parse(item.price),
title: item.title,
);
int i = cart.indexWhere((previousItem) => previousItem.id == newItem.id);
if (i > -1) {
cart[i].count++;
} else {
cart.add(newItem);
}
notifyListeners();
}
removeItemFromCart({#required item}) {
int index = cart.indexWhere((element) => element.id == item.id);
if (index > -1) {
if (cart[index].count > 1) {
cart[index].count--;
} else {
cart.removeWhere((element) => element.id == item.id);
}
}
notifyListeners();
}
clearCart() {
cart.clear();
notifyListeners();
}
int get totalPrice =>
cart.fold(0, (total, current) => total + (current.price * current.count));
}
This is menuitem.dart
class MenuItem extends StatelessWidget {
final dynamic foodItem;
MenuItem({#required this.foodItem});
void _showSecondPage(BuildContext context) {
Navigator.of(context).push(
MaterialPageRoute(
builder: (ctx) => Scaffold(
backgroundColor: Colors.black45,
body: Center(
child: Hero(
tag: foodItem.imgPath,
child: Image(image: NetworkImage(base_url + foodItem.imgPath)),
),
),
),
),
);
}
#override
Widget build(BuildContext context) {
int itemIndex = Provider.of<Cart>(context, listen: false)
.cart
.indexWhere((item) => item.id == foodItem.id);
return Container(
height: 80,
padding: EdgeInsets.symmetric(horizontal: 10, vertical: 10),
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
crossAxisAlignment: CrossAxisAlignment.center,
children: [
Row(
crossAxisAlignment: CrossAxisAlignment.center,
children: [
GestureDetector(
onTap: () => _showSecondPage(context),
child: Hero(
tag: foodItem.imgPath,
child: CircleAvatar(
backgroundImage: NetworkImage(base_url + foodItem.imgPath),
),
),
),
SizedBox(
width: 15,
),
Column(
crossAxisAlignment: CrossAxisAlignment.start,
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: [
Text(
foodItem.title,
style: TextStyle(
fontWeight: FontWeight.w700,
fontSize: 17,
),
),
Text('${foodItem.price.toString()} сум'),
],
)
],
),
Container(
width: 160,
child: Row(
crossAxisAlignment: CrossAxisAlignment.center,
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: <Widget>[
IconButton(
icon:
Icon(Icons.remove, color: Theme.of(context).primaryColor),
onPressed: () {
Provider.of<Cart>(context, listen: false)
.addItemToCart(item: foodItem);
},
),
Text(
itemIndex > -1
? '${Provider.of<Cart>(context).cart[itemIndex].count}'
: '0',
style: TextStyle(fontSize: 18),
),
IconButton(
icon: Icon(Icons.add, color: Theme.of(context).primaryColor),
onPressed: () {
Provider.of<Cart>(context, listen: false)
.addItemToCart(item: foodItem);
},
),
],
),
),
],
),
);
}
}
This is consumer part:
import 'package:counter/common/socketio.dart';
import 'package:counter/data/models/cart_model.dart';
import 'package:counter/presentation/widgets/empty_cart.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import 'package:shared_preferences/shared_preferences.dart';
class OrderReview extends StatefulWidget {
#override
_OrderReviewState createState() => _OrderReviewState();
}
class _OrderReviewState extends State<OrderReview> {
bool isCommentEnabled = false;
String guestCount;
String comment = '';
final _formKey = GlobalKey<FormState>();
#override
Widget build(BuildContext context) {
final myCart = context.watch<Cart>();
return Scaffold(
resizeToAvoidBottomInset: true,
appBar: AppBar(
title: Text('Проверка заказа'),
),
body: Builder(
builder: (context) {
if (myCart.cart.length > 0) {
handleOrderCreate() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
String userId = prefs.getString('userId');
String tableNum = prefs.getString('tableNum');
String status = 'accepted';
print('$userId, $tableNum, $status');
Map orderToCreate = {
'tableNum': tableNum,
'status': 'accepted',
'userId': userId,
'guestCount': guestCount,
'comment': comment,
'foodList': myCart.cart
};
socketIO.emit('createOrder', json.encode(orderToCreate));
Navigator.of(context).pushNamed('/home');
Provider.of<Cart>(context, listen: false).clearCart();
}
return GestureDetector(
onTap: () => FocusScope.of(context).requestFocus(new FocusNode()),
child: LayoutBuilder(
builder:
(BuildContext context, BoxConstraints viewportConstraints) {
return SingleChildScrollView(
child: ConstrainedBox(
constraints: BoxConstraints(
minHeight: viewportConstraints.maxHeight,
),
child: IntrinsicHeight(
child: Container(
padding: const EdgeInsets.symmetric(
horizontal: 8.0, vertical: 8.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.stretch,
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
Form(
key: _formKey,
child: Column(
children: [
Container(
height: 350,
decoration: BoxDecoration(
color: Colors.white,
borderRadius: BorderRadius.only(
topLeft: Radius.circular(10),
topRight: Radius.circular(10),
bottomLeft: Radius.circular(10),
bottomRight: Radius.circular(10)),
boxShadow: [
BoxShadow(
color:
Colors.grey.withOpacity(0.5),
spreadRadius: 5,
blurRadius: 7,
offset: Offset(0,
3), // changes position of shadow
),
]),
child: ListView.separated(
itemBuilder:
(BuildContext context, int i) {
return ListTile(
title: Text(myCart.cart[i].title),
trailing: Container(
width: 160,
child: Row(
crossAxisAlignment:
CrossAxisAlignment.center,
mainAxisAlignment:
MainAxisAlignment
.spaceBetween,
children: <Widget>[
IconButton(
icon: Icon(
Icons.remove,
color: Theme.of(context)
.primaryColor,
),
onPressed: () {
Provider.of<Cart>(context,
listen: false)
.removeItemFromCart(
item: myCart
.cart[i]);
},
),
Text(
'${myCart.cart[i].count}',
style:
TextStyle(fontSize: 18),
),
IconButton(
icon: Icon(
Icons.add,
color: Theme.of(context)
.primaryColor,
),
onPressed: () {
Provider.of<Cart>(context,
listen: false)
.addItemToCart(
item: myCart
.cart[i]);
},
),
],
),
),
);
},
separatorBuilder:
(BuildContext context, int) {
return Divider(
height: 2,
color: Colors.grey,
);
},
itemCount: myCart.cart.length,
),
),
SizedBox(height: 20),
Container(
child: TextFormField(
keyboardType: TextInputType.number,
decoration: InputDecoration(
border: OutlineInputBorder(),
hintText: 'Количество гостей',
),
onChanged: (newValue) {
setState(() => guestCount = newValue);
},
validator: (value) {
if (value == null || value.isEmpty) {
return 'Пожалуйста, введите количество гостей!';
}
return null;
},
),
),
SizedBox(height: 20),
Container(
child: TextFormField(
onChanged: (newValue) {
setState(() => comment = newValue);
},
enabled: isCommentEnabled,
decoration: InputDecoration(
border: OutlineInputBorder(),
hintText:
'Лаваш острый, хот дог без майонеза и т.д.',
// labelText: 'Комментарий',
),
maxLines: 2,
),
),
Row(
children: [
Text('Комментарий'),
Switch(
value: isCommentEnabled,
onChanged: (bool value) {
setState(() =>
this.isCommentEnabled = value);
},
),
],
)
],
),
),
SizedBox(height: 20),
Row(
children: [
Text(
'Общая цена: ',
style: TextStyle(
fontSize: 20,
fontWeight: FontWeight.w500,
),
),
SizedBox(width: 20),
Text(
'${myCart.totalPrice} сум',
style: TextStyle(fontSize: 18),
),
],
),
Container(
height: 50,
width: 170,
child: ElevatedButton(
style: ButtonStyle(
backgroundColor:
MaterialStateProperty.resolveWith(
(states) =>
Theme.of(context).primaryColor),
),
onPressed: () {
if (_formKey.currentState.validate()) {
handleOrderCreate();
}
},
child: Text(
'Отправить',
style: TextStyle(
color: Colors.white, fontSize: 18),
),
),
),
],
),
),
),
),
);
},
),
);
} else {
print('111');
return EmptyCart();
}
},
),
);
}
}
Is there something wrong with my code?