dart

问题 I'm trying to use DefaultTabController in the middle of some widgets. So my TabBar could not be in AppBar and has to be down some widgets. So my problem is when I use TabBarView it crashes... So here's an example of Flutter sample but no found how to do it without Scaffold . final List<Tab> myTabs = <Tab>[ Tab(text: 'LEFT'), Tab(text: 'RIGHT')]; Code DefaultTabController( length: myTabs.length, child: Scaffold( appBar: TabBar( tabs: myTabs, ), body: TabBarView( children: myTabs.map((Tab tab)

问题 Sorry I am now in programming, but I an learning do please help me. I am stuck at this issue. This is one of my first app, and allmost done so need at likke help to get it done. I am getting this error: type '_InternalLinkedHashMap' is not a subtype of type 'DocumentSnapshot' The code looks like this: import 'package:flutter/material.dart'; import 'package:brew_app/services/auth.dart'; import 'package:cloud_firestore/cloud_firestore.dart'; class Home extends StatelessWidget { final

问题 I am making BackBtn class which is used at many places in this application. Designs are the same and only the behavier when it pressed is different. So, I want to pass the function in constructor, which is used when the button pressed. However it shows the error below flutter: ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════ flutter: The following assertion was thrown building BackBtn(dirty): flutter: setState() or markNeedsBuild() called

问题 I'm using a DropDownButton with a custom style inside a ListView. My problem is: the PopupMenu opens about 200-300px below the Button so it looks like the Button below that has opened: I wrapped the Dropdown in a custom style, but i already tried removing that and that did nothing. I've also tried to use just a normal Dropdownbutton, but that had the same effect. the corresponding build: @override Widget build(BuildContext context) { homeModel = Provider.of<HomeModel>(context); model =

问题 I'm using a DropDownButton with a custom style inside a ListView. My problem is: the PopupMenu opens about 200-300px below the Button so it looks like the Button below that has opened: I wrapped the Dropdown in a custom style, but i already tried removing that and that did nothing. I've also tried to use just a normal Dropdownbutton, but that had the same effect. the corresponding build: @override Widget build(BuildContext context) { homeModel = Provider.of<HomeModel>(context); model =

问题 I tried several ways to make status bar icons dark, but after home press and returning to app status bar icons are white! it seems that its flutter bug. but in iOS it works fine. i tried these ways : android app style: <item name="android:windowLightStatusBar">false</item> AppBar brightness: brightness: Brightness.dark Flutter API: SystemChrome.setSystemUIOverlayStyle(SystemUiOverlayStyle.dark.copyWith( statusBarIconBrightness: Brightness.dark )); flutter_statusbarcolor package : import

问题 I tried several ways to make status bar icons dark, but after home press and returning to app status bar icons are white! it seems that its flutter bug. but in iOS it works fine. i tried these ways : android app style: <item name="android:windowLightStatusBar">false</item> AppBar brightness: brightness: Brightness.dark Flutter API: SystemChrome.setSystemUIOverlayStyle(SystemUiOverlayStyle.dark.copyWith( statusBarIconBrightness: Brightness.dark )); flutter_statusbarcolor package : import

问题 I tried several ways to make status bar icons dark, but after home press and returning to app status bar icons are white! it seems that its flutter bug. but in iOS it works fine. i tried these ways : android app style: <item name="android:windowLightStatusBar">false</item> AppBar brightness: brightness: Brightness.dark Flutter API: SystemChrome.setSystemUIOverlayStyle(SystemUiOverlayStyle.dark.copyWith( statusBarIconBrightness: Brightness.dark )); flutter_statusbarcolor package : import

问题 How to call Dart method from C++ code? I want to try use Dart as scripting language in my application. 回答1: You have two possibilities: First, you can embed the Dart VM into your C++ program . See this discussion (there is a GitHub example). This allows you to write you program in C++ and run Dart scripts. I don't think that this way is supported by the Dart team directly, you need to do many things yourself. Second, you can embed your C++ code into the Dart VM as a native extension. See this

问题 I have a DataTable widget for displaying some data in tabular format. I wasn't able to find any way to change the background color of the DataColumn , it defaults to white. I tried wrapping the label inside a Container but that does not help since the container takes the dimensions of the child. Is there any easier way to set the background color of `DataColum'? Below is some code for reference - DataTable( dataRowHeight: 70, headingRowHeight: 60, rows: List.generate(4, (index) { return