Develop Reference

How to scroll when + button is clicked in flutter?

I want when I click on the + Button it shows the next 3 containers that in the listVeiw it is horizontally direction.
Here is my code.
when I tap for the first time it works, but it doesn't work for the others taps
import 'package:flutter/material.dart';
class FindCars extends StatefulWidget {
const FindCars({Key? key}) : super(key: key);
#override
State<NewWayToFindCars> createState() => _NewWayToFindCarsState();
}
class _NewWayToFindCarsState extends State<NewWayToFindCars> {
var pricesListNumber = 10;
int counter = 1;
List months = [
'يناير',
'فبراير',
'مارس',
'ابريل',
'مايو',
'يونيو',
'يوليو',
'اغسطس',
'سبتمبر',
'اكتوبر',
'نوفمبر',
'ديسمبر'
];
var currentMonth = new DateTime.now().month;
var currentDay = new DateTime.now().day;
late ScrollController _scrollController;
#override
void initState() {
_scrollController = ScrollController();
super.initState();
}
#override
Widget build(BuildContext context) {
print(months[currentMonth - 1]);
print(currentDay);
print(DateTime.now());
return Container(
width: MediaQuery.of(context).size.width,
height: MediaQuery.of(context).size.height,
child: Directionality(
textDirection: TextDirection.rtl,
child: Column(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: [
Text(
'${months[currentMonth - 1]} 2022',
style: TextStyle(
fontSize: 20,
fontWeight: FontWeight.bold,
color: Colors.black,
fontFamily: 'cairo',
),
),
Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
InkWell(
onTap: () {
_scrollController.animateTo(-200,
duration: const Duration(milliseconds: 500),
curve: Curves.easeInOut);
},
child: Container(
child: Icon(Icons.remove, size: 22),
width: 50,
height: 50,
decoration: BoxDecoration(
color: Color(0xFFDCEDC8).withOpacity(0.5),
border: Border.all(
color: Color(0xFFDDE7DD).withOpacity(0.5),
width: 2.5,
),
borderRadius: BorderRadius.only(
topLeft: Radius.circular(10),
bottomLeft: Radius.circular(10),
),
),
),
),
InkWell(
onTap: () {
_scrollController.animateTo(200,
duration: const Duration(milliseconds: 500),
curve: Curves.easeInOut);
},
child: Container(
child: Center(child: Icon(Icons.add_sharp, size: 22)),
width: 50,
height: 50,
decoration: BoxDecoration(
color: Color(0xFFDCEDC8).withOpacity(0.25),
border: Border.all(
color: Color(0xFFDDE7DD).withOpacity(0.5),
width: 2.5,
),
borderRadius: BorderRadius.only(
topRight: Radius.circular(10),
bottomRight: Radius.circular(10),
),
),
),
),
],
),
Container(
width: MediaQuery.of(context).size.width,
height: MediaQuery.of(context).size.height * 0.1,
child: ListView(
controller: _scrollController, // scroll contoller
scrollDirection: Axis.horizontal,
children: new List.generate(
pricesListNumber,
(index) => Padding(
padding: const EdgeInsets.all(8.0),
child: Container(
child: Center(child: Text('${currentDay++}')),
decoration: BoxDecoration(
boxShadow: [
BoxShadow(
color: Colors.grey.withOpacity(0.5),
spreadRadius: 5,
blurRadius: 7,
offset: Offset(0, 3), // changes position of shadow
),
],
color: Color(0xFFDCEDC8).withOpacity(0.5),
border: Border.all(
color: Color(0xFFDDE7DD).withOpacity(0.5),
width: 2.5,
),
borderRadius: BorderRadius.circular(10),
),
height: 50,
width: MediaQuery.of(context).size.width * 0.25,
),
),
),
),
),
],
),
),
);
}
}
Here is my code for the UI, and now it is only works in the first click put it does not work until the end.
Can you please help me with that?

Attach a ScrollController to your scrollable widget and then use scrollController.animateTo(//offset) to reach where you want.
Do check the animateTo method on this page.
EDIT:
sample code:
ScrollController scrollController = ScrollController();
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Flutter'),
centerTitle: true,
),
body: Column(
children: [
ElevatedButton(
onPressed: () {
scrollController.animateTo(0,
duration: Duration(seconds: 1), curve: Curves.easeIn);
},
child: Text("go top")),
Expanded(
flex: 1,
child: ListView.builder(
controller: scrollController,
itemCount: 100,
itemBuilder: (context, index) {
return Text('This is it.');
},
),
),
],
),
);
}
Try it in your IDE.
EDIT:
Here is the problem in your code, you need to decrease/increase the current offset of the scroll controller by subtracting/adding 200 from the scrollController.position. You are getting it moved for the first time because at that time offset is not at 200 and for the second time it is there at 200. That is why it is not moving which is obviously no error.

Just use a scrollController, attach it to your ListView builder,
then on your Button's onPress/onTap method, call _scrolController.animateTo(someOffset)
Copy the code below and run into your project. I have customized it based on your needs.
import 'package:flutter/material.dart';
class TestView extends StatefulWidget {
const TestView({Key? key}) : super(key: key);
#override
State<TestView> createState() => _TestViewState();
}
class _TestViewState extends State<TestView> {
late ScrollController _scrollController;
#override
void initState() {
_scrollController = ScrollController();
super.initState();
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(),
body: Column(
children: [
Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
ElevatedButton(
onPressed: () {
_scrollController.animateTo(-500,
duration: const Duration(milliseconds: 500),
curve: Curves.easeInOut);
},
child: const Text("-")),
ElevatedButton(
onPressed: () {
_scrollController.animateTo(500,
duration: const Duration(milliseconds: 500),
curve: Curves.easeInOut);
},
child: const Text("+"),
),
],
),
SizedBox(
height: 200,
child: ListView(
controller: _scrollController,
scrollDirection: Axis.horizontal,
children: List.generate(20, (index) {
return Container(
color: Colors.amber,
height: 100,
width: 100,
margin: const EdgeInsets.only(right: 10),
child: Center(child: Text("$index")),
);
}),
),
)
],
),
);
}
}

The parameter 'size' can't have a value of 'null' because of its type in Dart

I am new to flutter and dart , I have a problem where the parameter size cant have null value. I tried to search in the google the same problem that people had been facing and the solution is to add 'required'. i had tried that but the problem is in my body
Below here is my CustomCard().
import 'package:flutter/material.dart';
import '../../constants.dart';
class CustomCard extends StatefulWidget {
final Size size;
final Icon icon;
final String title, statusOn, statusOff;
const CustomCard(
{ required Key key,
required this.size,
required this.icon,
required this.title,
required this.statusOn,
required this.statusOff})
: super(key: key);
#override
_CustomCardState createState() => _CustomCardState();
}
class _CustomCardState extends State<CustomCard>
with SingleTickerProviderStateMixin {
late AnimationController _animationController;
late Animation<Alignment> _animation;
bool isChecked = true;
void initState() {
_animationController = AnimationController(
vsync: this,
duration: Duration(milliseconds: 350),
);
_animation = Tween<Alignment>(
begin: Alignment.bottomCenter, end: Alignment.topCenter)
.animate(
CurvedAnimation(
parent: _animationController,
curve: Curves.linear,
reverseCurve: Curves.easeInBack,
),
);
super.initState();
}
#override
Widget build(BuildContext context) {
return Container(
height: 140,
width: widget.size.width * 0.35,
decoration: BoxDecoration(
color: kBgColor,
borderRadius: BorderRadius.circular(20),
boxShadow: [
BoxShadow(
color: Colors.black12,
blurRadius: 8,
offset: Offset(3, 3),
),
BoxShadow(
color: Colors.white,
blurRadius: 8,
offset: Offset(-3, -3),
),
],
),
child: Padding(
padding: EdgeInsets.all(15),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
widget.icon,
AnimatedBuilder(
animation: _animationController,
builder: (animation, child) {
return GestureDetector(
onTap: () {
setState(() {
if (_animationController.isCompleted) {
_animationController.animateTo(20);
} else {
_animationController.animateTo(0);
}
isChecked = !isChecked;
});
},
child: Container(
height: 40,
width: 25,
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(20),
color: Colors.grey.shade50,
boxShadow: [
BoxShadow(
color: Colors.grey.shade200,
blurRadius: 0,
offset: Offset(3, 3),
),
BoxShadow(
color: Colors.black12,
blurRadius: 5,
offset: Offset(-3, -3),
),
],
),
child: Align(
alignment: _animation.value,
child: Container(
height: 15,
width: 15,
margin: EdgeInsets.symmetric(
vertical: 2, horizontal: 1),
decoration: BoxDecoration(
color: isChecked
? Colors.grey.shade300
: kGreenColor,
shape: BoxShape.circle,
),
),
),
),
);
},
),
],
),
SizedBox(height: 10),
Text(
widget.title,
style: TextStyle(
fontSize: 16,
fontWeight: FontWeight.bold,
color: kBlueColor,
),
),
Text(
isChecked ? widget.statusOff : widget.statusOn,
style: TextStyle(
fontWeight: FontWeight.bold,
color: kGreenColor,
),
),
],
)),
);
}
}
And below here is my Body.dart
import 'package:flutter/material.dart';
import 'package:neew/constants.dart';
import 'package:neew/MainScreen/custom_card.dart';
class MainScreenBody extends StatefulWidget {
#override
_MainScreenBodyState createState() => _MainScreenBodyState();
}
class _MainScreenBodyState extends State<MainScreenBody> {
#override
Widget build(BuildContext context) {
Size size = MediaQuery.of(context).size;
return Padding(
padding: EdgeInsets.all(8.0),
child: Column(
children: [
SizedBox(height: size.height * 0.1),
Center(
child: Text(
"My Home",
textAlign: TextAlign.center,
style: TextStyle(
fontWeight: FontWeight.bold,
color: Colors.black,
fontSize: 25,
),
),
),
SizedBox(height: size.height * 0.05),
CustomCard(
size: size,
icon: Icon(
Icons.home_outlined,
size: 55,
color: Colors.grey.shade400,
),
title: 'Entry',
statusOn: 'OPEN',
statusOff: 'LOCKED',
)
],
),
);
}
}
The error that i detect in body dart is in CustomCard().
Please help me, I will really appreciate it.

Nested Gesture Does not change on Tap

I am currently working on the ui stuff for the appliction, so the thing is i have one gesture as a parent that swipes up and down and based on it the position of the widgets gets changed but the problem is the child gesture does not get any precedence when tapped on it it gives the precedence. So my tree structure is Pageview.builder which has single widget with topmost parent as Gesturedetector and the children accrodingly, Can any one tell me what i am doing wrong or any improvements to get the gesture for each.
Below is the sample code that i have been working on:
import 'dart:math';
import 'package:LocationAnimation/Model/device_model.dart';
import 'package:LocationAnimation/SplashPage/splash_page.dart';
import 'package:LocationAnimation/widgets/device_function_widget.dart';
import 'package:flutter/material.dart';
import 'package:flutter_svg/flutter_svg.dart';
import 'package:google_fonts/google_fonts.dart';
import 'Model/device_model.dart' as devices;
import 'Model/locations_model.dart' as locations;
import 'extensions/capitalize.dart';
void main() {
runApp(new MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
title: 'HAL',
home: MyHomePage(),
);
}
}
class SampleList {
final String locationName;
SampleList({this.locationName});
}
class MyHomePage extends StatefulWidget {
#override
State createState() => new MyHomePageState();
}
class MyHomePageState extends State<MyHomePage> with TickerProviderStateMixin {
final _controller = new PageController();
final _kArrowColor = Colors.black.withOpacity(0.8);
bool _isSwipe = false;
bool _isLoading = false;
var list = [
SampleList(locationName: 'Living Room'),
SampleList(locationName: 'Bed Room'),
SampleList(locationName: 'Back Porch Lights'),
SampleList(locationName: 'Basement Porch Lights'),
SampleList(locationName: 'Sample Room'),
];
#override
Widget build(BuildContext context) {
return new Scaffold(
body: new IconTheme(
data: new IconThemeData(color: _kArrowColor),
child: new Stack(
children: <Widget>[
new PageView.builder(
physics: _isSwipe
? NeverScrollableScrollPhysics()
: AlwaysScrollableScrollPhysics(),
controller: _controller,
itemCount: list.length,
itemBuilder: (BuildContext context, int index) {
return LocationDetails(
isLoading: _isLoading,
item: list[index],
onSwipeDown: () {
setState(() {
_isSwipe = false;
});
},
onSwipeUp: () {
setState(() {
_isSwipe = true;
});
},
);
},
),
],
),
),
);
}
}
class LocationDetails extends StatefulWidget {
final bool isLoading;
SampleList item;
final Function() onSwipeUp;
final Function() onSwipeDown;
LocationDetails(
{Key key, this.item, this.onSwipeUp, this.onSwipeDown, this.isLoading})
: super(key: key);
#override
_LocationDetailsState createState() => _LocationDetailsState();
}
class _LocationDetailsState extends State<LocationDetails> {
DragStartDetails startVerticalDragDetails;
DragUpdateDetails updateVerticalDragDetails;
bool moveWidget = false;
bool dismissSwipeText = true;
bool _isRotate = false;
int currentSelectedIndex = 0;
bool ignoreChildGestures = true;
bool _isSwpie = false;
#override
Widget build(BuildContext context) {
return Scaffold(
body: SafeArea(
child: Container(
child: GestureDetector(
onTap: () {
print('Tap');
},
onVerticalDragStart: (dragDetails) {
startVerticalDragDetails = dragDetails;
},
onVerticalDragUpdate: (dragDetails) {
updateVerticalDragDetails = dragDetails;
},
onVerticalDragEnd: (endDetails) {
double dx = updateVerticalDragDetails.globalPosition.dx -
startVerticalDragDetails.globalPosition.dx;
double dy = updateVerticalDragDetails.globalPosition.dy -
startVerticalDragDetails.globalPosition.dy;
double velocity = endDetails.primaryVelocity;
//Convert values to be positive
if (dx < 0) dx = -dx;
if (dy < 0) dy = -dy;
if (velocity < 0) {
widget.onSwipeUp();
print('drag up');
setState(() {
moveWidget = true;
_isSwpie = true;
});
} else {
widget.onSwipeDown();
print(' drag down');
setState(() {
moveWidget = false;
_isSwpie = false;
});
}
},
child: Container(
height: MediaQuery.of(context).size.height,
width: MediaQuery.of(context).size.width,
decoration: new BoxDecoration(
image: new DecorationImage(
colorFilter: ColorFilter.mode(
Colors.black.withOpacity(0.8), BlendMode.srcOver),
image: /* moveWidget
? */
AssetImage(
'Assets/backgroundImage.jpg',
),
/* : NetworkImage(widget.samplePage.networkImage), */
fit: BoxFit.fill,
),
),
child:
/* widget.isLoading
? Center(
child: CircularProgressIndicator(),
)
: */
Stack(
children: <Widget>[
AnimatedOpacity(
opacity: moveWidget ? 0 : 1,
duration: Duration(microseconds: 100),
child: Padding(
padding: const EdgeInsets.all(20.0),
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: <Widget>[
Column(
children: <Widget>[
Icon(
Icons.power_settings_new,
color: Colors.white,
size: 30,
),
Icon(
Icons.more_horiz,
color: Colors.white,
size: 25,
)
],
),
Row(
children: <Widget>[
Column(
children: <Widget>[
Text(
'Inside Temp',
style: TextStyle(
color: Colors.white, fontSize: 18),
),
SizedBox(
height: 5,
),
Row(
children: <Widget>[
Icon(
Icons.ac_unit,
color: Colors.white,
size: 20,
),
SizedBox(
width: 10,
),
Text(
'19 C',
style: TextStyle(color: Colors.white),
),
],
)
],
),
SizedBox(
width: 10,
),
Column(
children: <Widget>[
Text(
'Outside Temp',
style: TextStyle(
color: Colors.white, fontSize: 18),
),
SizedBox(
height: 5,
),
Row(
children: <Widget>[
Icon(
Icons.ac_unit,
color: Colors.white,
size: 20,
),
SizedBox(
width: 10,
),
Text(
'19 C',
style: TextStyle(color: Colors.white),
),
],
)
],
),
],
)
],
),
),
),
AnimatedPositioned(
onEnd: () {
setState(() {
dismissSwipeText = !dismissSwipeText;
//print(dismissSwipeText);
});
},
curve: Curves.ease,
duration: Duration(milliseconds: 700),
bottom: moveWidget
? 10
: MediaQuery.of(context).size.height * 0.18,
left: 10.0,
right: 0.0,
top: moveWidget
? 50
: MediaQuery.of(context).size.height * 0.75,
child: AnimatedOpacity(
opacity: dismissSwipeText ? 1 : 0,
duration: Duration(milliseconds: 500),
child: Text(
'Swipe up to customize',
style: TextStyle(color: Colors.white, fontSize: 20),
),
),
),
AnimatedPositioned(
curve: Curves.ease,
duration: Duration(milliseconds: 700),
onEnd: () {
setState(() {
_isSwpie = true;
});
},
left: 10,
top: moveWidget
? 80
: MediaQuery.of(context).size.height * 0.80,
child: Container(
width: MediaQuery.of(context).size.width * 0.97,
child: Row(
mainAxisAlignment: MainAxisAlignment.start,
children: <Widget>[
GestureDetector(
onTap: () {
setState(() {
currentSelectedIndex = 0;
});
},
child: Container(
width: MediaQuery.of(context).size.width * 0.20,
height:
MediaQuery.of(context).size.height * 0.10,
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(20),
color: currentSelectedIndex == 0
? Colors.blue
: Colors.grey[900],
),
child: Center(
child: Text(
'Lights',
style: GoogleFonts.lato(
color: Colors.white,
fontWeight: FontWeight.w700),
)),
),
),
Row(
children: <Widget>[
SizedBox(
width: 10,
),
GestureDetector(
onTap: () {
setState(() {
currentSelectedIndex = 1;
});
},
child: Container(
width: MediaQuery.of(context).size.width *
0.20,
height: MediaQuery.of(context).size.height *
0.10,
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(20),
color: currentSelectedIndex == 1
? Colors.blue
: Colors.grey[900],
),
child: Center(
child: Text(
'Applicanes',
style: GoogleFonts.lato(
color: Colors.white,
fontWeight: FontWeight.w700),
)),
),
),
],
),
Row(
children: <Widget>[
SizedBox(
width: 10,
),
GestureDetector(
onTap: () {
setState(() {
currentSelectedIndex = 2;
});
},
child: Container(
width: MediaQuery.of(context).size.width *
0.20,
height: MediaQuery.of(context).size.height *
0.10,
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(20),
color: currentSelectedIndex == 2
? Colors.blue
: Colors.grey[900],
),
child: Center(
child: Text(
'Sensors',
style: GoogleFonts.lato(
color: Colors.white,
fontWeight: FontWeight.w700),
)),
),
),
],
),
Row(
children: <Widget>[
SizedBox(
width: 10,
),
Container(
width:
MediaQuery.of(context).size.width * 0.20,
height:
MediaQuery.of(context).size.height * 0.10,
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(20),
color: Colors.grey[900],
),
child: Center(
child: Text(
'Doors \n& Locks',
style: GoogleFonts.lato(
color: Colors.white,
fontWeight: FontWeight.w700),
)),
),
],
),
SizedBox(
width: 10,
),
],
),
),
),
AnimatedPositioned(
curve: Curves.ease,
duration: Duration(milliseconds: 400),
bottom: moveWidget
? 10
: MediaQuery.of(context).size.height * 0.20,
left: 10.0,
right: 0.0,
top: moveWidget
? 15
: MediaQuery.of(context).size.height * 0.70,
child: Text(
'${widget.item.locationName}',
style: TextStyle(fontSize: 30, color: Colors.white),
),
),
],
)),
),
),
),
);
}
}

You can add Color to the last AnimatedPositioned which use text widget.item.locationName in your code, like:
AnimatedPositioned(
curve: Curves.ease,
duration: Duration(milliseconds: 400),
bottom: moveWidget
? 10
: MediaQuery.of(context).size.height * 0.20,
left: 10.0,
right: 0.0,
top: moveWidget
? 15
: MediaQuery.of(context).size.height * 0.70,
child: Container(
color: Colors.white,
Text(
'${widget.item.locationName}',
style: TextStyle(fontSize: 30, color: Colors.white),
),
),
),
You will see a white screen (the widget which blocking you) when you scroll up. You can fix it by 2 ways
Change the bottom 10 to a larger number
Move this part of AnimatedPositioned to Top of the Stack widget
The Nested Gesture should work probably as you expected.

First of All you are using multiple Scaffold in a single page which is not recommended.
And remove the unwanted widgets from your tree which will help you to debug a way more better level. And Next you can try with passing a Callback function from parent to child which can eventually solve your problem

why unnecessary values overriding when calculating total in flutter

when i try to increase the quantity the total amount showing big numbers and when i exit the page and reenter it showing correct out put why this happenning...?this happens when i increase or decrease the quantity
this happens when i exit the page and reenter
import 'package:flutter/material.dart';
import 'package:hive/hive.dart';
import 'package:appnew/src/hivedatabase/cart_model.dart';
import 'package:hive_flutter/hive_flutter.dart';
import 'package:appnew/src/widgets/totalprice.dart';
List<String> compnme = List();
List<String> compqnt = List();
class CartPage extends StatefulWidget {
#override
_CartPageState createState() => _CartPageState();
}
class _CartPageState extends State<CartPage> {
double sum = 0;
final cartBox = Hive.box('carts');
final totBox = Hive.box('tot');
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
elevation: 1,
backgroundColor: Colors.lightGreen,
title: Text(
'Cart',
),
),
body: _buildListView(),
bottomNavigationBar: Container(
color: Colors.white,
child: Row(
children: <Widget>[
Expanded(
child: _buildtotal(),
),
Expanded(
child: new MaterialButton(
onPressed: () {
final cartBox = Hive.box('carts');
cartBox.clear();
compnme.clear();
compqnt.clear();
totBox.clear();
},
child: new Text(
"Check Out",
style: TextStyle(color: Colors.white),
),
color: Colors.red,
)),
],
),
),
);
}
Widget _buildListView() {
// ignore: deprecated_member_use
return WatchBoxBuilder(
box: Hive.box('carts'),
builder: (context, cartBox) {
return ListView.builder(
itemCount: cartBox.length,
itemBuilder: (BuildContext context, int index) {
final cartModel = cartBox.getAt(index) as CartModel;
double iprice = double.parse(cartModel.price);
double nprice = 0;
int iquant = int.parse(cartModel.quantitys);
return Card(
elevation: 5,
child: Container(
height: 130,
child: Row(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Container(
height: 129,
width: 125,
decoration: BoxDecoration(
image: DecorationImage(
image: NetworkImage(cartModel.img),
fit: BoxFit.fill,
),
),
),
Container(
height: 130,
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Padding(
padding: const EdgeInsets.fromLTRB(0, 10, 0, 5),
child: Text(
cartModel.pname,
style: TextStyle(fontSize: 20),
),
),
Padding(
padding: EdgeInsets.fromLTRB(0, 4, 0, 3),
child: Container(
width: 160,
child: Text(cartModel.curquant,
style: TextStyle(fontSize: 17)),
),
),
Padding(
padding: EdgeInsets.fromLTRB(1, 25, 0, 0),
child: Text("Rs." + cartModel.price,
style: TextStyle(
fontSize: 19, color: Colors.black54)),
)
],
),
),
Padding(
padding: const EdgeInsets.fromLTRB(0, 77, 19, 2),
child: Container(
height: 90,
child: IconButton(
icon: Icon(Icons.add_circle,
size: 35, color: Colors.green[300]),
onPressed: () {
iquant++;
nprice = iprice + (iprice / (iquant - 1));
cartBox.putAt(
index,
CartModel(
cartModel.pname,
cartModel.curquant,
cartModel.img,
nprice.toString(),
iquant.toString()));
}),
),
),
Padding(
padding: const EdgeInsets.fromLTRB(0, 77, 0, 2),
child: Container(
height: 90,
child: CircleAvatar(
backgroundColor: Colors.grey[300],
maxRadius: 16,
child: Text(cartModel.quantitys),
),
),
),
Padding(
padding: const EdgeInsets.fromLTRB(19, 77, 0, 2),
child: Container(
height: 90,
child: IconButton(
icon: Icon(Icons.remove_circle,
size: 35, color: Colors.redAccent),
onPressed: () {
if (iquant == 1) {
cartBox.deleteAt(index);
print(compnme[index]);
compnme.removeAt(index);
compqnt.removeAt(index);
} else {
iquant--;
nprice = iprice - (iprice / (iquant + 1));
cartBox.putAt(
index,
CartModel(
cartModel.pname,
cartModel.curquant,
cartModel.img,
nprice.toString(),
iquant.toString()));
}
}),
),
)
],
),
),
);
},
);
},
);
}
Widget _buildtotal() {
// ignore: deprecated_member_use
return WatchBoxBuilder(
box: Hive.box('carts'),
builder: (context, cartBox) {
for (int i = 0; i < cartBox.length; i++) {
final cartModel = cartBox.getAt(i) as CartModel;
double iprice = double.parse(cartModel.price);
sum += iprice;
print(sum);
}
return ListTile(
title: new Text("total:", style: TextStyle(color: Colors.black)),
subtitle: new Text(sum.toString(),
style: TextStyle(
color: Colors.black,
fontSize: 16,
)),
);
});
}
}
i tried adding setState() in buttons and functions but it didnt worked

Just assign zero each time in _buildtotal() method
Widget _buildtotal() {
sum=0;//This will reset sum value zero before re-calculating total
// ignore: deprecated_member_use
return WatchBoxBuilder(
box: Hive.box('carts'),
builder: (context, cartBox) {
for (int i = 0; i < cartBox.length; i++) {
final cartModel = cartBox.getAt(i) as CartModel;
double iprice = double.parse(cartModel.price);
sum += iprice;
print(sum);
}
return ListTile(
title: new Text("total:", style: TextStyle(color: Colors.black)),
subtitle: new Text(sum.toString(),
style: TextStyle(
color: Colors.black,
fontSize: 16,
)),
);
});
}

Flutter update data onClick at clicked index

I am building a food cart application and have a query on the menu item page.
My menu items page consists of a list view, which shows each item with description along with an option to specify the quantity of items( 1, 2, 3....)
Now I am able to increment or decrement item count for a single item, but not sure how to do that in a list view at a particular index where the user clicks.
Could some one please help me on this?
The code which I have done till now is as below :
FutureBuilder(
future: getItemList(),
builder: (context, snapshot) {
if (!snapshot.hasData) {
return CircularProgressIndicator();
}
var itemList = snapshot.data;
int itemlength = itemList.length;
return ListView.builder(
scrollDirection: Axis.vertical,
shrinkWrap: true,
itemBuilder: (BuildContext context, int index) {
return Container(
height: 100,
margin: EdgeInsets.only(left: 10, right: 10, top: 10),
decoration: BoxDecoration(
color: Colors.white70,
border: Border.all(width: 2.0, color: Colors.blueGrey),
borderRadius: BorderRadius.circular(6.0),
boxShadow: [
BoxShadow(
color: Color(0xFF6078ea).withOpacity(.3),
offset: Offset(0.0, 8.0),
blurRadius: 8.0),
],
),
child: Row(
children: < Widget > [
Container(
width: 75,
child: ClipRRect(
borderRadius: new BorderRadius.circular(10.0),
child: Image(
image: AssetImage(
'assets/images/loginbg3.jpg'),
fit: BoxFit.cover,
),
),
margin: EdgeInsets.only(left: 10),
),
Expanded(
child: Container(
child: Column(
children: < Widget > [
Row(
children: < Widget > [
Expanded(child: Container(margin: EdgeInsets.only(left: 10, top: 15, bottom: 5), child: Text(itemList[index]['itemname'], style: kClickableTextStyle, ))),
Container(color: Colors.white, width: 25, margin: EdgeInsets.only(left: 10, top: 15, bottom: 5), child: Image.asset(_itemtype)),
],
),
Row(
children: < Widget > [
Container(margin: EdgeInsets.only(left: 10, top: 15, bottom: 5), child: Text('Price : ', style: kListTitleTextStyle, )),
Container(margin: EdgeInsets.only(left: 10, top: 15, bottom: 5), child: Text(numberofitems.toString() + ' \u20B9 ', style: kListTitleTextStyle, )),
],
),
],
),
),
),
Container(
margin: EdgeInsets.only(left: 10),
child: Row(
children: < Widget > [
InkWell(
onTap: onClickDelete,
child: Container(
width: 30, child: Icon(
Icons.remove_circle_outline,
color: Colors.green,
size: 30,
), ),
),
Container(
width: 30,
child: Center(child: Text(_count.toString(), style: TextStyle(fontSize: 25), )),
),
InkWell(
onTap: onClickAdd,
child: Container(
margin: EdgeInsets.only(right: 5),
width: 30, child: Icon(
Icons.add_circle_outline,
color: Colors.green,
size: 30,
), ),
),
],
),
),
],
),
);
},
itemCount: itemList == null ? 0 : itemList.length,
);
})

You can copy paste run full code below
Step 1: create Item class
Step 2: change future builder call
Step 3: deal with Inkwell onTap
working demo
code snippet
Future callback;
#override
void initState() {
callback = _getItemList();
super.initState();
}
#override
Widget build(BuildContext context) {
var futureBuilder = FutureBuilder(
future: callback,
...
InkWell(
onTap: () {
if (itemList[index].numberofitems > 0) {
setState(() {
itemList[index].numberofitems =
itemList[index].numberofitems - 1;
});
}
},
...
InkWell(
onTap: () {
setState(() {
itemList[index].numberofitems =
itemList[index].numberofitems + 1;
print(
' ${itemList[index].itemname.toString()} ${itemList[index].numberofitems.toString()}');
});
},
full code
import 'dart:async';
import 'dart:collection';
import 'package:flutter/material.dart';
void main() => runApp( MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(),
);
}
}
class Item {
String itemname;
String itemtype;
int numberofitems;
Item({this.itemname, this.itemtype, this.numberofitems});
}
class MyHomePage extends StatefulWidget {
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
Future callback;
#override
void initState() {
callback = _getItemList();
super.initState();
}
#override
Widget build(BuildContext context) {
var futureBuilder = FutureBuilder(
future: callback,
builder: (BuildContext context, AsyncSnapshot snapshot) {
switch (snapshot.connectionState) {
case ConnectionState.none:
case ConnectionState.waiting:
return Center(child: CircularProgressIndicator());
default:
if (snapshot.hasError)
return Text('Error: ${snapshot.error}');
else
return createListView(context, snapshot);
}
},
);
return Scaffold(
appBar: AppBar(
title: Text("Home Page"),
),
body: futureBuilder,
);
}
Future<List<Item>> _getItemList() async {
var values = List<Item>();
values.add(
Item(itemname: "A", itemtype: "assets/images/a.jpg", numberofitems: 0));
values.add(
Item(itemname: "B", itemtype: "assets/images/a.jpg", numberofitems: 1));
values.add(
Item(itemname: "C", itemtype: "assets/images/a.jpg", numberofitems: 2));
//throw Exception("Danger Will Robinson!!!");
await Future.delayed( Duration(seconds: 2));
return values;
}
Widget createListView(BuildContext context, AsyncSnapshot snapshot) {
List<Item> itemList = snapshot.data;
return ListView.builder(
itemCount: itemList.length,
itemBuilder: (BuildContext context, int index) {
{
return Container(
height: 100,
margin: EdgeInsets.only(left: 10, right: 10, top: 10),
decoration: BoxDecoration(
color: Colors.white70,
border: Border.all(width: 2.0, color: Colors.blueGrey),
borderRadius: BorderRadius.circular(6.0),
boxShadow: [
BoxShadow(
color: Color(0xFF6078ea).withOpacity(.3),
offset: Offset(0.0, 8.0),
blurRadius: 8.0),
],
),
child: Row(
children: <Widget>[
Container(
width: 75,
child: ClipRRect(
borderRadius: BorderRadius.circular(10.0),
child: Image(
image: AssetImage('assets/images/a.jpg'),
fit: BoxFit.cover,
),
),
margin: EdgeInsets.only(left: 10),
),
Expanded(
child: Container(
child: Column(
children: <Widget>[
Row(
children: <Widget>[
Expanded(
child: Container(
margin: EdgeInsets.only(
left: 10, top: 15, bottom: 5),
child: Text(
itemList[index].itemname,
))),
Container(
color: Colors.white,
width: 25,
margin: EdgeInsets.only(
left: 10, top: 15, bottom: 5),
child: Image.asset(itemList[index].itemtype)),
],
),
Row(
children: <Widget>[
Container(
margin: EdgeInsets.only(
left: 10, top: 15, bottom: 5),
child: Text(
'Price : ',
)),
Container(
margin: EdgeInsets.only(
left: 10, top: 15, bottom: 5),
child: Text(
itemList[index].numberofitems.toString() +
' \u20B9 ',
)),
],
),
],
),
),
),
Container(
margin: EdgeInsets.only(left: 10),
child: Row(
children: <Widget>[
InkWell(
onTap: () {
if (itemList[index].numberofitems > 0) {
setState(() {
itemList[index].numberofitems =
itemList[index].numberofitems - 1;
});
}
},
child: Container(
width: 30,
child: Icon(
Icons.remove_circle_outline,
color: Colors.green,
size: 30,
),
),
),
Container(
width: 30,
child: Center(
child: Text(
itemList[index].numberofitems.toString(),
style: TextStyle(fontSize: 25),
)),
),
InkWell(
onTap: () {
setState(() {
itemList[index].numberofitems =
itemList[index].numberofitems + 1;
print(
' ${itemList[index].itemname.toString()} ${itemList[index].numberofitems.toString()}');
});
},
child: Container(
margin: EdgeInsets.only(right: 5),
width: 30,
child: Icon(
Icons.add_circle_outline,
color: Colors.green,
size: 30,
),
),
),
],
),
),
],
),
);
}
;
});
}
}

you need to create list of objects for your Item like.
class Item{
String name;
String description;
int quantity;
double price;
}
and on tap of item, get index of clicked item with new incremented/decremented value and update your list of objects inside setState().

You need to wrap your itemBuilder item, i.e the Container with a GestureDetector and then call the onTap() method inside that detector.
Before that, you'll have to convert your item into a stateful widget with a variable to maintain the count of quantity.