` setState(() {
//how to prevent set state in here
rating = aaa;
});
onChanged: (aaa) {
setState(() {
rating = aaa;
});
},`
You can use ValueListenableBuilder instead of setState.
Eg: If rating is type of int. So, you can make a type ValueNoifier of type int & listen to its changes.
ValueNotifier<int> rating = ValueNotifier<int>(0);
//......change the value of rating in the onChanged:
onChanged(aaa){
rating.value = aaa;
}
// .... Wrap your Widget with Listenable builder to listen to the change in rating.
ValueListenableBuilder(
valueListenable: rating,
builder : (context, value, child) => SomeWidget(......)
)
Related
guys
I'm trying to Create a list to add and delete items which are already stored in my database(MongoDB). I already created an Animated list that once its clicked on it deletes the item but as soon as i add the function to remove the item from the database it begins to show a loader as I used a ListView.builder
FutureBuilder(
builder: (context, projectSnap) {
if (projectSnap.connectionState == ConnectionState.none &&
projectSnap.hasData == null) {
//print('project snapshot data is: ${projectSnap.data}');
return Text('Nothing To show Here');
}else if(
projectSnap.connectionState == ConnectionState.waiting
) {
return Center(child: CircularProgressIndicator());
} else if(
projectSnap.connectionState == ConnectionState.active
) {
return AnimatedList(
padding: EdgeInsets.zero,
key: _listKey,
physics: NeverScrollableScrollPhysics(),
shrinkWrap: true,
initialItemCount: pairlenght,
itemBuilder: (BuildContext context, int index, animation) {
pair1 = pair[index].split(" ")[1];
pair0 = pair[index].split(" ")[0];
return _buildItem(pair, index, animation);
}
);
}
else{
return AnimatedList(
padding: EdgeInsets.zero,
key: _listKey,
physics: NeverScrollableScrollPhysics(),
shrinkWrap: true,
initialItemCount: pairlenght,
itemBuilder: (BuildContext context, int index, animation) {
pair1 = pair[index].split(" ")[1];
pair0 = pair[index].split(" ")[0];
return _buildItem(pair, index, animation);
}
);
}
},
future: fetchlist(),
),
This is the code for the list
void _removeSingleItems(int index) {
int removeIndex = index;
String removedItem = pair.removeAt(removeIndex);
// This builder is just so that the animation has something
// to work with before it disappears from view since the original
// has already been deleted.
AnimatedListRemovedItemBuilder builder = (context, animation) {
// A method to build the Card widget.
return _buildItem(removedItem, index, animation);
};
_listKey.currentState?.removeItem(removeIndex, builder);
}
This is the code to delete the item using Animated list
This is the how it works
So what I actually need is just a better alternative if listview.builder won't do the job.
Cause whenever I delete it loads again which I don't want
so, I am using a search Delegate to allow user search, however, when user is inputting data, it's really slow, it lags and skips frames as they type, because my search delegate loops through a list that contains about 2000 objects and checks user query against each object's title and main text, making about 4000 search criteria in total, this was causing the lag, so to solve this, I simply spawned a new isolate to handle the suggestions building, as such
Future<List<Data>> allData(String query) async {
List<Data> suggestions;
List<Data> myData(String message) {
return allData.where((data) {
final result = data.dataText.replaceAll(RegExp('[^A-Za-z0-9 ]'), '').toLowerCase();
final result1 = data.dataText.replaceAll(RegExp('[^A-Za-z0-9]'), '').toLowerCase();
final result2 = data.dataText.toLowerCase();
final result3 = data.dataText.replaceAll("th'incarnate", "the incarnate").toLowerCase();
final input = query.toLowerCase();
final result4 = data.dataTitle.toLowerCase();
final result5 = data.dataTitle.replaceAll(RegExp('[^A-Za-z0-9 ]'), '').toLowerCase();
final result6 =data.dataTitle.replaceAll(RegExp('[^A-Za-z0-9]'), '').toLowerCase();
return result.contains(input) ||
result1.contains(input) ||
result2.contains(input) ||
result3.contains(input) ||
result4.contains(input) ||
result5.contains(input) ||
result6.contains(input);
}).toList();
}
query.isEmpty
? suggestions = []
: suggestions = await compute<String, List<Data>>(
myData,
"",
);
if (query.isNotEmpty && suggestions.isEmpty) {
return [
Data(
DataTitle: "No Results",
DataText: "No Results",
),
];
} else {
return suggestions;
}
}
then in buildSuggestions I did this
#override
Widget buildSuggestions(BuildContext context) {
return FutureBuilder<List<Data>>(
future: DataBrain().allData(query),
builder: (context, snapshot) {
List<Data> suggestions;
query.isEmpty ? suggestions = [] : suggestions = snapshot.data!;
return ListView.builder(
itemCount: suggestions.length,
itemBuilder: (context, suggestIndex) {
final suggestion = suggestions[suggestIndex];
if (snapshot.connectionState == ConnectionState.done) {
if (suggestion.dataText.toLowerCase() == "no results") {
return const ListTile(
title: Text("No results"),
subtitle: Text("Please check for spelling mistakes"),
);
} else {
return ListTile(
title: Text(suggestion.dataTitle),
trailing: Text(
'${suggestion.dataBookName} ${suggestion.dataBookNumber == 0 ? '30a' : suggestion.dataBookNumber}',
style: const TextStyle(
fontStyle: FontStyle.italic,
fontWeight: FontWeight.w300,
),
),
onTap: () {
close(context, suggestion);
},
);
}
} else {
return const ListTile(
title: Text('Loading...'),
);
}
});
});
}
it works fine without lags, however now, the suggestions don't build as user types, it waits till user is no longer typing, for like 2 seconds, then it builds suggestions, I think this is because it's a future and in a future builder, I'm not sure why. I'm thinking of turning it into a stream rather and listen to query change and build immediately instead of awaiting for two seconds after user stops querying, is there any workaround, what's a good way to eliminate the delay, i need it to filter the list and build suggestions with each keystroke, as it used to do before i moved it to a new isolate and made it a future
Currently I'm using a loading page to avoid having a big lag when the user is being redirected to the home page while the notifications are being created on the same thread (the UI thread which leads to lots of dropped frames).
I tried using the compute dart function but the issue is that this function requires using static methods and you can't pass it objects.
So I would appreciate some hints on how to use a thread to create the notifications.
PS: in the worst scenario the app is creating 7*24 notifications(24 for each day of the week) which is slow even on high end devices.
import 'dart:async';
import 'package:flutter/foundation.dart';
import 'package:flutter_local_notifications/flutter_local_notifications.dart';
import 'package:flutter/material.dart';
import '../pages/home_page/home_page.dart';
import 'package:timezone/data/latest.dart' as tz;
import 'package:timezone/timezone.dart' as tz;
import 'data.dart';
import 'package:flutter_native_timezone/flutter_native_timezone.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:flutter_gen/gen_l10n/app_localizations.dart';
import 'package:auto_size_text/auto_size_text.dart';
class NotificationLoading extends StatefulWidget {
const NotificationLoading({Key? key}) : super(key: key);
#override
_NotificationLoadingState createState() => _NotificationLoadingState();
}
class _NotificationLoadingState extends State<NotificationLoading> {
#override
void initState() {
super.initState();
manageNotifications();
}
Future<void> manageNotifications() async {
await Future.delayed(
const Duration(seconds: 1),
); // Let time to build the widget
await Notifications(ctx: context).manageNotifications();
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.center,
children: const [
CircularProgressIndicator(),
Padding(
padding: EdgeInsets.fromLTRB(0, 15, 0, 0),
child: AutoSizeText(
"Loading notifs",
style: TextStyle(fontSize: 30),
),
)
],
),
),
);
}
}
class Notifications {
static const channelId = "coolID";
static const channelName = "cool";
Data data = Data();
int id = 0;
BuildContext ctx;
Notifications({required this.ctx});
FlutterLocalNotificationsPlugin flutterLocalNotificationsPlugin =
FlutterLocalNotificationsPlugin();
// check if notifications are already setup, if not setup notifications
// otherwise notifications only need to be changed inside the timer_page
Future<void> manageNotifications() async {
final prefs = await SharedPreferences.getInstance();
bool isNotificationSetup = prefs.getBool('isNotificationSetup') ?? false;
if (!isNotificationSetup) {
await _initialization();
await _scheduleNotifications();
await prefs.setBool('isNotificationSetup', true);
Navigator.pop(ctx);
await Navigator.push(
ctx,
MaterialPageRoute<void>(builder: (context) => const HomePage()),
);
}
}
Future<void> _initialization() async {
const AndroidInitializationSettings initializationSettingsAndroid =
AndroidInitializationSettings('app_icon');
const InitializationSettings initializationSettings =
InitializationSettings(
android: initializationSettingsAndroid,
);
await flutterLocalNotificationsPlugin.initialize(initializationSettings,
onSelectNotification: _selectNotification);
}
// Schedule notifications based on user settings
Future<void> _scheduleNotifications() async {
// Init the time zone, needed for notification scheduling
tz.initializeTimeZones();
final String? timeZoneName = await FlutterNativeTimezone.getLocalTimezone();
tz.setLocalLocation(tz.getLocation(timeZoneName!));
await data.getData();
int delta = (data.endTime.minute + data.endTime.hour * 60) -
(data.startTime.minute + data.startTime.hour * 60);
double interval = delta / data.reminderNumber;
data.checkedDays.forEach((day, values) {
if (values[1]) {
double minute = data.startTime.minute + (data.startTime.hour * 60);
for (int reminder = 0; reminder < data.reminderNumber; reminder++) {
int tmpHour = (minute - minute % 60) ~/ 60;
int tmpMinute = (minute.round()) % 60;
_createScheduledNotification(
_nextInstanceOfDayHourMinute(tmpHour, tmpMinute, values[0]), id);
minute += interval;
id++;
}
}
});
}
// Create a scheduled notification
void _createScheduledNotification(tz.TZDateTime time, int id) async {
await flutterLocalNotificationsPlugin.zonedSchedule(
id,
AppLocalizations.of(ctx)!.notificationTitle,
AppLocalizations.of(ctx)!.notificationMessage,
time,
const NotificationDetails(
android: AndroidNotificationDetails(
'weekly notification channel id',
'New citation message',
channelDescription:
'Notifications for new citations configured in the timer page.',
sound: RawResourceAndroidNotificationSound('notification_sound'),
groupKey: "meditation invitation",
),
),
androidAllowWhileIdle: true,
uiLocalNotificationDateInterpretation:
UILocalNotificationDateInterpretation.absoluteTime,
matchDateTimeComponents: DateTimeComponents.dayOfWeekAndTime);
}
// Find next instance DateTime object
tz.TZDateTime _nextInstanceOfHourMinute(int hour, int minute) {
final tz.TZDateTime now = tz.TZDateTime.now(tz.local);
tz.TZDateTime scheduledDate =
tz.TZDateTime(tz.local, now.year, now.month, now.day, hour, minute);
if (scheduledDate.isBefore(now)) {
scheduledDate = scheduledDate.add(const Duration(days: 1));
}
return scheduledDate;
}
// Find next instance DateTime object
tz.TZDateTime _nextInstanceOfDayHourMinute(int hour, int minute, int day) {
tz.TZDateTime scheduledDate = _nextInstanceOfHourMinute(hour, minute);
while (scheduledDate.weekday != day) {
scheduledDate = scheduledDate.add(const Duration(days: 1));
}
return scheduledDate;
}
// triggered function when the user tap on a notification
void _selectNotification(String? payload) async {
if (payload != null) {
debugPrint('notification payload: $payload');
}
await Navigator.push(
ctx,
MaterialPageRoute<void>(builder: (context) => const HomePage()),
);
}
}
You can't handle too many notifications at time in iOS platform. Instead of that you need again set or schedule notifications after few old notification received otherwise old notifications overlaps & it will not schedule.
You can check this link & my answer I hope it will help you.
Dart/Flutter is single threaded and not possible multi threading. As each isolate has its own memory,space and everything. To make it work like multi threaded you have to use isolates and the communication will be used through ports by sending message to one another. If you not want to use Future you can use isolates.
Read
https://medium.com/flutter-community/flutter-threading-5c3a7b0c065f
https://www.tutorialspoint.com/dart_programming/dart_programming_concurrency.htm
https://pub.dev/packages/threading
So you can use Future Or isolate.
Great François. You already in a good path. I guess i could give you some hints to accomplish what you want.
First of all Flutter require top level functions to run isolates so you have to put it outside of a class.
To transfer data to an isolate it must be serialized. In my example i use jsonEncode to send it as a string and parse it with jsonDecode to retrieve as a dynamic list inside the isolate runner.
When i wrote this code i read about some limitations of the use of plugins inside isolate (I don`t know about the current state). So i found a solution for this using Flutter Isolate plugin (https://pub.dev/packages/isolate_handler)
I use the function killScheduleNotifications as a way to control when the code is running and avoid to create duplications. I always cancel all the scheduled and recreate it every time.
For reference (https://gist.github.com/taciomedeiros/50472cf94c742befba720853e9d598b6)
final IsolateHandler isolateHandler = IsolateHandler();
void scheduleNotificationsIsolate(String _reminders) async {
await new Future.delayed(new Duration(milliseconds: 500));
// ... (describe settings)
flutterLocalNotificationsPlugin.initialize(
settings,
onSelectNotification: onSelectNotification,
);
await flutterLocalNotificationsPlugin.cancelAll();
List<dynamic> _remindersParsed = jsonDecode(_reminders);
for (// iterate over your entities to show the message) {
int generatedId = id ?? random.nextInt(1000000000);
await flutterLocalNotificationsPlugin.schedule(
generatedId,
title,
message,
scheduledNotificationDateTime,
platformSpecifics,
payload: payload,
);
}
killCurrentScheduleNotifications();
}
startScheduleNotifications(String _remindersAsString) {
killCurrentScheduleNotifications();
isolateHandler.spawn<String>(
entryPoint,
name: "scheduleNotifications",
onReceive: scheduleNotificationsIsolate,
onInitialized: () => isolateHandler.send(
_remindersAsString,
to: "scheduleNotifications",
),
);
}
void killCurrentScheduleNotifications() {
if (isolateHandler.isolates.containsKey('scheduleNotifications'))
isolateHandler.kill('scheduleNotifications');
}
void entryPoint(Map<String, dynamic> context) {
final messenger = HandledIsolate.initialize(context);
messenger.listen((message) {
messenger.send(message);
});
}
i've been working with wallpaper app.
i manage to call the path list for wallpaper,
i can make this work on image card list but i can't manage to do it work with assetPath for WallpaperManager
Please help, is there any way to do it?
Future<void> setWallpaperFromAsset() async {
setState(() {
_wallpaperAsset = "Loading";
});
String result;
String assetPath = ('Load List here');
You can add a parameter assetPath to setWallpaperFromAsset
Future<void> setWallpaperFromAsset(String assetPath) async {
setState(() {
_wallpaperAsset = "Loading";
});
String result;
// Platform messages may fail, so we use a try/catch PlatformException.
try {
result = await WallpaperManager.setWallpaperFromAsset(
assetPath, WallpaperManager.HOME_SCREEN);
} on PlatformException {
result = 'Failed to get wallpaper.';
}
}
And you register the onPressed callback with:
RaisedButton.icon(
onPressed: () => setWallpaperFromAsset(item),
icon: Icon (Icons.wallpaper, size: 20),
label: Text('homescreen')),
)
I write an app in flutter. I want to change the state of a string variable. After I set the state of the string variable, the ModalRoute PopUpMenu does not show the changed variable. If I close the ModalRoute PopUpMenu and open it again, I can see the changed variable.
I tried to pop the context, but I want the change on the PopUpMenu. I've got my own Overlay widget.
class MyOverlay extends ModalRoute {
...
}
// this is my main.dart:
List<String> categories = ['please', 'help', 'me'];
String _selectedCategory = 'category';
// this is where the PopUpMenu starts
floatingActionButton: FloatingActionButton(
child: ...,
onPressed: () {
_showPopup(context, _popupBody(), 'Add');
},
),
_showPopup(BuildContext context, Widget widget, String title, {BuildContext popupContext}) {
Navigator.push(
context,
MyOverlay(
...
onPressed: () {
try {
Navigator.pop(context); //close the popup
} catch (e) {
print(e);
}
},
...
body: widget,
) ...
);
}
Widget _popupBody() {
...
PopupMenuButton<String>(
// HERE IS THE PROBLEM THIS SHOULD CHANGE WHEN I SELECT
child: Text('$_selectedCategory'),
itemBuilder: (BuildContext context) {
return categories.map((String choice) {
return PopupMenuItem<String>(
value: choice,
child: Text(choice),
);
}).toList();
},
onSelected: _selectCategory,
),
...
}
void _selectCategory(String category) {
setState(() => this._selectedCategory = category);
}
The text widget does not change if I select the PopupMenuItem.
I have the same problem, I fixed for the moment using changedExternalState (); to force a rebuild, but i think maybe this isn't optimal.
Example:
CheckboxListTile(
value: _checkboxValue,
title: Text(phone),
onChanged: (value){
_checkboxValue = value;
//Fix
changedExternalState();
},
)