dart

How to implement Flood-fill algorithms?

由 岁酱吖の 提交于 2021-02-09 09:02:52
问题 I am working on one Paint application wherein I am implementing BucketFill functionality similar to MS paint application. I have coded it using a couple of FloodFill algorithms but the filling color process is taking too much time. I am not pretty sure reasons behind it may happen due to the low cache memory, poor algorithm, or it may be taking a lot of time calculating offsets. Can someone help me out with your Knowledge in Flutter/Dart? Algorithms tried: Recursion Based Approach(4 or 8

How to implement Flood-fill algorithms?

由 谁说我不能喝 提交于 2021-02-09 09:01:38
问题 I am working on one Paint application wherein I am implementing BucketFill functionality similar to MS paint application. I have coded it using a couple of FloodFill algorithms but the filling color process is taking too much time. I am not pretty sure reasons behind it may happen due to the low cache memory, poor algorithm, or it may be taking a lot of time calculating offsets. Can someone help me out with your Knowledge in Flutter/Dart? Algorithms tried: Recursion Based Approach(4 or 8

How to implement Flood-fill algorithms?

由 我的未来我决定 提交于 2021-02-09 09:01:09
问题 I am working on one Paint application wherein I am implementing BucketFill functionality similar to MS paint application. I have coded it using a couple of FloodFill algorithms but the filling color process is taking too much time. I am not pretty sure reasons behind it may happen due to the low cache memory, poor algorithm, or it may be taking a lot of time calculating offsets. Can someone help me out with your Knowledge in Flutter/Dart? Algorithms tried: Recursion Based Approach(4 or 8

why abstract class instantiation isn't runtime error in dart?

由 为君一笑 提交于 2021-02-09 05:50:09
问题 In many languages if you try to instantiate abstract class you get compile time error. In Dart however, you get warning while compiling and a runtime exception AbstractClassInstantiationError . Why is that? Can someone provide an example, where it's reasonable to compile such code? 回答1: Dart tries to allow you to run your program while you are developing it. That is why many things that are compile time errors in other languages are compile-time warnings and runtime errors in Dart. This

How to handle searching Large Lists in Flutter?

由 柔情痞子 提交于 2021-02-09 05:13:21
问题 I want to ask how I should handle a large list in Flutter. My app gets super slow when I am at a data item that is really deep in the list which I am searching. My list is 70,000+ objects of a data structure large. The following is how I am "Searching" the list. Future<Iterable<SomeDataStruct>> _getAllData() async { return allData.where((a) => (a.dataTitle.toLowerCase().contains(querySearch.toLowerCase().trim()))); } Building the list using a ListView.builder inside of a FutureBuilder. When I

闲鱼在ServiceMesh的探索和实践

由 蹲街弑〆低调 提交于 2021-02-09 03:35:23
　　背景： 　　 　　在阿里服务端开发以Java为主的大背景下，其他异构语言业务如何调用现有Java服务，如何与集团中间件打通，就成为使用非Java语言团队必须要解决的首要问题。 　　 　　已有方案问题： 　　 　　在ServiceMesh方案成熟之前，我们采用：通过Dart C/C++扩展方式调用各中间件客户端SO库（类JNI）。该方案在业务初期很好的解决了Dart服务端生态建设问题。但是该方案还存在以下几个问题： 　　 　　运维耦合度高。业务代码和客户端SO库代码打包在一起，运行在同一进程，一旦微服务框架需要升级，业务代码也需要维护和重启。 　　 　　复杂性：进程内的多个语言环境，跨语言数据表示和传输等问题，都会增加系统的复杂性，降低原有服务的性能。 　　 　　接入成本高 　　 　　新功能滞后 　　 　　ServiceMesh方案: 　　 　　由于现有方案存在的一些问题，我们转向ServiceMesh寻找解决问题的思路 　　 　　如上图所示：与目前比较常见的微服务框架相比，ServiceMesh把微服务客户端核心功能独立出来，并作为一个独立Proxy进程部署在每一个主机上，业务进程通过Proxy进程与外界通信。这个独立的Proxy进程就是ServiceMesh的核心: SideCar。 　　 　　业务进程和SideCar之间最常见的两种通信方案：1.

Get Variables name by it's value in Dart Lang

由 那年仲夏 提交于 2021-02-08 23:43:09
问题 For Example, I have a variable like this. var fooBar = 12; I want a something like this in Dart lang. print_var_name(fooBar); which prints: fooBar How can I achieve that? Is this even possible? Thank you. 回答1: There is no such thing in Dart for the web or for Flutter. Reflection can do that, but reflection is only supported in the server VM because it hurts tree-shaking. You need to write code for that manually or use code generation where you need that. An example class SomeClass { String

how to add multiple ChangeNotifierProvider in same type in Flutter

由 谁都会走 提交于 2021-02-08 19:43:53
问题 Is it possible to add same type multiple ChangeNotifierProvider? return MultiProvider( providers: [ ChangeNotifierProvider<ValueNotifier<double>>( create: (_) => ValueNotifier<double>(0.0), ), ChangeNotifierProvider<ValueNotifier<double>>( create: (_) => ValueNotifier<double>(0.0), ), ], In my build method @override Widget build(BuildContext context) { ValueNotifier<double> firstNotifier = Provider.of(context, listen: true); ValueNotifier<double> secondNotifier = Provider.of(context, listen:

how to add multiple ChangeNotifierProvider in same type in Flutter

由 左心房为你撑大大i 提交于 2021-02-08 19:42:05
问题 Is it possible to add same type multiple ChangeNotifierProvider? return MultiProvider( providers: [ ChangeNotifierProvider<ValueNotifier<double>>( create: (_) => ValueNotifier<double>(0.0), ), ChangeNotifierProvider<ValueNotifier<double>>( create: (_) => ValueNotifier<double>(0.0), ), ], In my build method @override Widget build(BuildContext context) { ValueNotifier<double> firstNotifier = Provider.of(context, listen: true); ValueNotifier<double> secondNotifier = Provider.of(context, listen:

How to filter a list of obseravble in rxdart

由 房东的猫 提交于 2021-02-08 19:41:59
问题 I am trying to implement bloc pattern in rxdart . I am trying to build todo app type of app . I implemented showing all items in list but what I want is not to show completed and uncompleted items in different part . However I am not able to filter the items based on completed on rxdart . import 'package:rxdart/rxdart.dart'; import '../models/ShoppingItem.dart'; class ShoppingItemBloc { final _shoppingItems = BehaviorSubject<List<ShoppingItem>> (seedValue: []); Observable<List<ShoppingItem>>
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