How to jump between controls with 'tab' in flutter for web? - user-interface

I want user to be able to jump between controls with 'Tab' in my flutter web app.
I followed this post to catch the key "Tab" and to navigate to next controls.
When user presses 'Tab', cursor jumps to the next text box, but then, when user types, no letters appears in the text box.
What can be wrong?
Here is the code:
class _LoginScreenState extends State<LoginScreen> {
FocusNode _passwordFocus;
FocusNode _emailFocus;
#override
void initState() {
super.initState();
_emailFocus = FocusNode();
_passwordFocus = FocusNode();
}
#override
void dispose() {
_emailFocus.dispose();
_passwordFocus.dispose();
super.dispose();
}
#override
Widget build(BuildContext context) {
final TextEditingController emailController =
new TextEditingController(text: this._email);
final TextEditingController passwordController =
new TextEditingController();
return Scaffold(
appBar: AppBar(
title: Text('Sign In'),
),
body: Column(
children: <Widget>[
RawKeyboardListener(
child: TextField(
autofocus: true,
controller: emailController,
decoration: InputDecoration(
labelText: "EMail",
),
),
onKey: (dynamic key) {
if (key.data.keyCode == 9) {
FocusScope.of(context).requestFocus(_passwordFocus);
}
},
focusNode: _emailFocus,
),
TextField(
controller: passwordController,
obscureText: true,
focusNode: _passwordFocus,
decoration: InputDecoration(
labelText: "Password",
),
),
],
),
);
}
}

It turned out the browser was taking the focus to other place.
I added prevention of default browser behavior to the method 'build':
import 'dart:html';
...
#override
Widget build(BuildContext context) {
document.addEventListener('keydown', (dynamic event) {
if (event.code == 'Tab') {
event.preventDefault();
}
});
...

The solution that worked for me is a little different.
I am on Flutter 2.0.1 with Dart 2.12.0
import 'dart:html';
import 'package:flutter/foundation.dart';
...
#override
Widget build(BuildContext context) {
if (kIsWeb) {
document.addEventListener('keydown',
(event) => {if (event.type == 'tab') event.preventDefault()});
}
...
}
...

Related

Changing the AppBar colour when a new tab is selected (Flutter)

I have an app with a tab bar and to make the UI better, I wanted to make it so that the colour changes when you got to another tab. How do I make it so that when I click or swipe to another tab, let's say the yellow tab, the whole appbar changes to that colour?
Code:
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return ChangeNotifierProvider<ColorChange>(
create: (context) => ColorChange(),
child: MaterialApp(
theme: ThemeData.light(),
home: SimpleTab(),
),
);
}
}
class _TestPageState extends State<TestPage> {
TabController controller;
class ColorChange extends ChangeNotifier {
Color color = colors[0];
Color getColor() {
return color;
}
void changeColor() {
color = colors[controller.index];
print(color);
notifyListeners();
}
}
List<Color> colors = const [
Colors.green,
Colors.yellow,
Colors.red,
Colors.blue,
Colors.deepOrange,
Colors.deepPurple,
];
class SimpleTab extends StatefulWidget {
#override
_SimpleTabState createState() => _SimpleTabState();
}
class _SimpleTabState extends State<SimpleTab>
with SingleTickerProviderStateMixin {
Tester tester = Tester();
#override
void initState() {
super.initState();
controller = TabController(length: colors.length, vsync: this);
controller.addListener(ColorChange().changeColor);
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("Simple Tab Demo"),
backgroundColor: Provider.of<ColorChange>(context).getColor(),
bottom: TabBar(
controller: controller,
tabs: [
Tab(
text: 'Green',
),
Tab(
text: 'Yellow',
),
Tab(
text: 'Red',
),
Tab(
text: 'Blue',
),
Tab(
text: 'Orange',
),
Tab(
text: 'Purple',
),
],
isScrollable: true,
),
),
body: TabBarView(
controller: controller,
children: <Widget>[
Container(
// child: WidgetThing(tester: tester),
),
Container(
// child: WidgetThing(tester: tester),
),
Container(
// child: WidgetThing(tester: tester),
),
Container(
// child: WidgetThing(tester: tester),
),
Container(
// child: WidgetThing(tester: tester),
),
Container(
// child: WidgetThing(tester: tester),
),
],
),
);
}
}
This is just a very simplified demo of my real app. My real app deals with a lot of data fetched from APIs, hence it is probably better if setstate() was not used, because re-building the whole widget may call http requests unnecessarily.
You can try this
import 'package:flutter/material.dart';
void main() {
runApp(new MyApp());
}
class MyApp extends StatelessWidget {
Widget build(BuildContext context) {
return new MaterialApp(
title: 'Demo App',
theme: new ThemeData(
primarySwatch: Colors.blue,
),
home: new MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
#override
_MyHomePageState createState() => new _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
#override
Widget build(BuildContext context) {
return new Scaffold(
body: SimpleTab(),
);
}
}
class CustomTab {
const CustomTab({this.title, this.color});
final String title;
final Color color;
}
class SimpleTab extends StatefulWidget {
#override
_SimpleTabState createState() => _SimpleTabState();
}
class _SimpleTabState extends State<SimpleTab>
with SingleTickerProviderStateMixin {
TabController controller;
List<CustomTab> tabs = const <CustomTab>[
const CustomTab(title: 'Home', color: Colors.deepOrangeAccent),
const CustomTab(title: 'Setting', color: Colors.blueGrey),
const CustomTab(title: 'Map', color: Colors.teal),
];
CustomTab selectedTab;
#override
void initState() {
super.initState();
controller = new TabController(length: tabs.length, vsync: this);
controller.addListener(_select);
selectedTab = tabs[0];
}
void _select() {
setState(() {
selectedTab = tabs[controller.index];
});
}
#override
Widget build(BuildContext context) {
textStyle() {
return new TextStyle(color: Colors.white, fontSize: 30.0);
}
return new Scaffold(
appBar: new AppBar(
title: new Text("Smiple Tab Demo"),
backgroundColor: selectedTab.color,
bottom: new TabBar(
controller: controller,
tabs: tabs
.map((e) => new Tab(
text: e.title,
))
.toList()),
),
body: new TabBarView(
controller: controller,
children: tabs
.map(
(e) => new Container(
color: e.color,
child: new Center(
child: new Text(
e.title,
style: textStyle(),
),
),
),
)
.toList()),
);
}
}

Validator to TextField

How can I implement a validator to a TextField. I know TextFormField has a validator option, but I need the validator in a TextField. If the TextField value is not valid I need to decorate it, just like a TextFormField.
You can do like this:
class MyHomePage extends StatefulWidget {
#override
MyHomePageState createState() {
return new MyHomePageState();
}
}
class MyHomePageState extends State<MyHomePage> {
final _text = TextEditingController();
bool _validate = false;
#override
void dispose() {
_text.dispose();
super.dispose();
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('TextField Demo'),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text('Error Showed if Field is Empty on Submit button Pressed'),
TextField(
controller: _text,
decoration: InputDecoration(
labelText: 'Enter the Value',
errorText: _validate ? 'Value Can\'t Be Empty' : null,
),
),
RaisedButton(
onPressed: () {
setState(() {
_text.text.isEmpty ? _validate = true : _validate = false;
});
},
child: Text('Submit'),
textColor: Colors.white,
color: Colors.blueAccent,
)
],
),
),
);
}
}
This code shows error text when the user don't enter anything in the TextField

How to implement event listener or delegate on flutter

I have a main dart class in which the app bar is located and the app bar contains a refresh button. I'm using a navigation drawer to populate two other views f1 and f2.
From my main.dart how can I pass the refresh button clicks to the sub fragment kind of f1.dart so that I can refresh my contents on f1.dart
// State of Main
class _MyHomePageState extends State<MyHomePage> {
#override
Widget build(BuildContext context) {
return Scaffold(
drawer: Drawer(
child: new Column(
children: <Widget>[
////////////////////////////////////////////////////////////
new FirstFragment(),
new SecondFragment()
/////////////////////////////////////////////////////////////
],
),
),
appBar: AppBar(
title: Text(widget.title),
actions: <Widget>[
IconButton(
icon: Icon(Icons.refresh),
onPressed: () {
print("refresh pressed");
/////////////////////////
How to send this refresh pressed event to my FirstFragment class??
/////////////////////////
},
color: Colors.white,
)
],
),
body: _getDrawerItemWidget(_selectedDrawerIndex),
);
}
}
In Android, I've been using event listeners and for iOS, I can use delegates for the purpose. How can I achieve this on flutter/dart. ?
You can pass a callback, use the VoidCallback and receive the event on your Main widget.
class MainPage extends StatelessWidget {
_onTapButton() {
print("your event here");
}
#override
Widget build(BuildContext context) {
return Container(
child: ChildPage(
onTap: _onTapButton,
),
);
}
}
class ChildPage extends StatelessWidget {
final VoidCallback onTap;
const ChildPage({Key key, this.onTap}) : super(key: key);
#override
Widget build(BuildContext context) {
return Container(
child: RaisedButton(
child: Text("Click Me"),
onPressed: () {
//call to your callback here
onTap();
},
),
);
}
}
In case you want the opposite, you can just refresh the state of your parent widget and change the parameter that you pass to your fragments or also you can use GlobalKey, like the example below:
class MainPage extends StatelessWidget {
final GlobalKey<ChildPageState> _key = GlobalKey();
_onTapButton() {
_key.currentState.myMethod();
}
#override
Widget build(BuildContext context) {
return Container(
child: Column(
children: [
ChildPage(
key: _key,
),
RaisedButton(
child: Text("Click me"),
onPressed: _onTapButton,
)
],
)
);
}
}
class ChildPage extends StatefulWidget {
const ChildPage({Key key}) : super(key: key);
#override
ChildPageState createState() {
return new ChildPageState();
}
}
class ChildPageState extends State<ChildPage> {
myMethod(){
print("called from parent");
}
#override
Widget build(BuildContext context) {
return Container(
child: Text("Click Me"),
);
}
}

Is there a way I can read thumbnails from phone gallery?

I am trying to display all the phone gallery images myself by reading the external files directory and possibly every image that ends with jpg or png. I achieved that, but could not display all of them in a grid as due to their sizes or the no. of images, the app crashes. Code looks bit like this..
new GridView.count(
shrinkWrap: true,
physics: new ClampingScrollPhysics(),
crossAxisCount: 2,
// children: new List<Widget>.generate(_images.length, (index) {
// children: new List<Widget>.generate(allImages.length, (index) {
children: new List<Widget>.generate(_PhoneImages.length, (index) {
File imgFile = _phoneImageFiles[index];
thumbBytes = _phoneThumbBytes[index]; // assuming it got created!!!
// print('thumbbytes $thumbBytes');
print('phone image index: $index');
return new GridTile(
child: new GestureDetector(
child: new Stack(
children: [
new Card(
// color: Colors.blue.shade200,
color: Colors.white70,
child: new Center(
// child: new Text('tile $index'),
// child: new Image.asset(_images[index]),
/*
child: new CachedNetworkImage(
imageUrl: allImages[index].path,
// placeholder: new CircularProgressIndicator(),
errorWidget: new Icon(Icons.error),
)
*/
child: new Image.file(imgFile,
// child: new Image.memory(thumbBytes,
So I tried the imageresize library which tells me to do a heavy operation of resizing, that takes almost 20 minutes before I can show the thumbnails.
All I need is to read thumbnails from gallery like how the phone gallery displays. I don't need categorization. I need all and a link to their full version so that I can do something with them later on.
I think this might help multi_image_picker
e.g
import 'package:flutter/material.dart';
import 'package:multi_image_picker/asset.dart';
class AssetView extends StatefulWidget {
final int _index;
final Asset _asset;
AssetView(this._index, this._asset);
#override
State<StatefulWidget> createState() => AssetState(this._index, this._asset);
}
class AssetState extends State<AssetView> {
int _index = 0;
Asset _asset;
AssetState(this._index, this._asset);
#override
void initState() {
super.initState();
_loadImage();
}
void _loadImage() async {
await this._asset.requestThumbnail(300, 300); // here requesting thumbnail
setState(() {});
}
#override
Widget build(BuildContext context) {
if (null != this._asset.thumbData) {
return Image.memory(
this._asset.thumbData.buffer.asUint8List(),
fit: BoxFit.cover,
);
}
return Text(
'${this._index}',
style: Theme.of(context).textTheme.headline,
);
}
}
import 'package:flutter/material.dart';
import 'dart:async';
import 'package:flutter/services.dart';
import 'package:multi_image_picker/asset.dart';
import 'package:multi_image_picker/multi_image_picker.dart';
import 'asset_view.dart';
void main() => runApp(new MyApp());
class MyApp extends StatefulWidget {
#override
_MyAppState createState() => new _MyAppState();
}
class _MyAppState extends State<MyApp> {
List<Asset> images = List<Asset>();
String _error;
#override
void initState() {
super.initState();
}
Widget buildGridView() {
return GridView.count(
crossAxisCount: 3,
children: List.generate(images.length, (index) {
return AssetView(index, images[index]);
}),
);
}
Future<void> loadAssets() async {
setState(() {
images = List<Asset>();
});
List resultList;
String error;
try {
resultList = await MultiImagePicker.pickImages(
maxImages: 300,
);
} on PlatformException catch (e) {
error = e.message;
}
// If the widget was removed from the tree while the asynchronous platform
// message was in flight, we want to discard the reply rather than calling
// setState to update our non-existent appearance.
if (!mounted) return;
setState(() {
images = resultList;
if (error == null) _error = 'No Error Dectected';
});
}
#override
Widget build(BuildContext context) {
return new MaterialApp(
home: new Scaffold(
appBar: new AppBar(
title: const Text('Plugin example app'),
),
body: Column(
children: <Widget>[
Center(child: Text('Error: $_error')),
RaisedButton(
child: Text("Pick images"),
onPressed: loadAssets,
),
Expanded(
child: buildGridView(),
)
],
),
),
);
}
}

Flutter - setState Not Using New Data

I have a screen which I pass data back to like so:
final myUpdatedObject = await Navigator.of(context).push(...);
setState({
object = myUpdatedObject;
});
Having checked with a simple print at all places in my widget body that my object is used, the new data is present after it is passed back by the Navigator and setState is called.
However, when the widget is rebuilt, even though the new data is apparently there, it is not reflected in the UI changes, it shows old data.
Is this some sort of caching in debug mode? Whats causing this issue?
The example below starts with a Map named textMessageMap with a message key that populates a Text Widget with 'Home'. Tap the FloatingActionButton and you'll navigate to SecondScreen. If you tap the 'Go back!' button in SecondScreen, the message key in textMessageMap will be updated to read 'Second Screen'. If you tap the back button on the Scaffold of SecondScreen, textMessageMap will be nulled out. Calling setState updates the UI appropriately. See if your implementation is different.
import 'package:flutter/material.dart';
void main() => runApp(new MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return new MaterialApp(
title: 'Flutter Demo',
theme: new ThemeData(
primarySwatch: Colors.blue,
),
home: new MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
#override
_MyHomePageState createState() => new _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
Map<String, String> textMessageMap = {'message': 'Home'};
#override
Widget build(BuildContext context) {
return new Scaffold(
appBar: new AppBar(
title: new Text(widget.title),
),
body: new Center(
child: new Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
new Text(
'${textMessageMap != null ? textMessageMap['message'] : 'map is null'}',
style: Theme.of(context).textTheme.display1,
),
],
),
),
floatingActionButton: new FloatingActionButton(
onPressed: () {
_launchSecondScreen();
},
child: new Icon(Icons.add),
),
);
}
_launchSecondScreen() async {
final value = await Navigator.push(
context,
MaterialPageRoute<Map<String, String>>(
builder: (BuildContext _) => SecondScreen()));
setState(() {
textMessageMap = value;
});
}
}
class SecondScreen extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("Second Screen"),
),
body: Center(
child: RaisedButton(
onPressed: () {
// Navigate back to the first screen by popping the current route
// off the stack. The text 'Second Screen' will replace 'Home'.
// If you hit the scaffold's back button, the return value will be
// null instead.
final map = {'message': 'Second Screen'};
Navigator.pop(context, map);
},
child: Text('Go back!'),
),
),
);
}
}

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