I want to explain something in my app and add a widget which looks like a notification or chat. I want this widget to be visible for some time and then get dismissed. I tried using tooltip but it is visible only when I click it.
Which widget can I use?
The Dart package intro_views_flutter is what you need, but one of its main limitations is that it is displayed on full screen, if that is not an issue to you, then you should take a look at it. Or you can use a showDialog method inside a Future function this way :
Future showNotification() async {
showDialog<String>(
context: context,
child: new AlertDialog(
title: Text('Note!') ,
contentPadding: const EdgeInsets.all(16.0),
content: //any widget you want to display here
),
);
await new Future.delayed(const Duration(seconds: 5), () {
Navigator.of(context).pop(); // this will dismiss the dialog automatically after five seconds
}
}
then when you need it call:
showNotificaion();
Related
How can you programatically perform a button click in Flutter? I basically want to bind a number of buttons to keys on the keyboard, the most important part is that after a key is pressed the corresponding button the visual state of the button is triggered to inform the user which button was pressed.
I am aware you can invoke the onTap function, but that by itself doesn't update the visual state of button. Is there a way to simulate this kind of behavior, I tried to look into MaterialStateController but doesn't feel like it's the right approach.
I was going to say that you could use the MaterialStateController to simulate that the button has been pressed.
This can be done by updating the state controller in some good enough fashion of your choice. Something like this perhaps:
Non-optimized code for this (you will bind to keys on the keyboard instead):
ElevatedButton(
onPressed: () async {
button2StatesController.update(MaterialState.pressed, true);
await Future.delayed(const Duration(milliseconds: 200));
button2StatesController.update(MaterialState.pressed, false);
},
child: const Text('Button 1'),
),
ElevatedButton(
onPressed: () {},
statesController: button2StatesController,
child: const Text('Button 2'),
)
You cannot simulate the InkWell effect (as far as I know) without more intervention. Like creating your own button with your own inkwell animations etc...
I discovered that _InkWellResponseState (internal-) classes have a function called simulateTap. The function is bound against ActivateIntent and by default this intend is fired whenever the user presses Enter or Space
class SimActivateIntent extends ActivateIntent {
const SimActivateIntent (this.model);
final FocusNode model;
}
class SimActivateAction extends Action<SimActivateIntent> {
SimActivateAction ();
#override
void invoke(covariant SimActivateIntentintent) {
Actions.maybeInvoke(intent.model.context!, const ActivateIntent());
}
}
With the intends listed above one can invoke the ActivateIntent on a specific object and simulate a button press. They can bound into the application using Shortcuts & Actions classes.
Map<ShortcutActivator, Intent> get defaultShortcuts {
return <ShortcutActivator, Intent>{
const SingleActivator(LogicalKeyboardKey.backspace):
SimActivateIntent(digitBackspace),
}
}
#override
Widget build(BuildContext context)
{
return Shortcuts(
shortcuts: defaultShortcuts,
child: Actions(
actions: <Type, Action<Intent>>{
SimActivateIntent: SimActivateAction(),
},
child: ...
));
}
I have 2 dart file. I want close the alertdialog from another dart file in specific conditions.
How can I ?
for example the function i want.(I wrote to express myself better.)
void example(){
if(control==false){
alertDialog.close();
}
Alert dialog file
class AlertForm extends StatefulWidget {
#override
_AlertFormState createState() => _AlertFormState();
}
class _AlertFormState extends State<AlertForm> {
void _showDialog() {
// flutter defined function
showDialog(
context: context,
builder: (BuildContext context) {
// return object of type Dialog
return AlertDialog(
title: new Text("Alert Dialog title"),
content: new Text("Alert Dialog body"),
actions: <Widget>[
// usually buttons at the bottom of the dialog
new FlatButton(
child: new Text("Close"),
onPressed: () {
Navigator.of(context).pop();
},
),
],
);
},
);
}
So what I want is to use the pop action in a function in another flutter file.
Call Navigator.of(context).pop(); inside the if block (of the void example function of the other Dart file) and the alert should close.
But here is the problem, the context above might not be part of or aware of the dialog and the above may not work.
More info about your setup would suggest a solution to this problem. Like how exactly does the other Dart file exist relative to the file where _showDialog is declared? If it's something you can easily provide context from AlertForm Dart file to the closingDialog Dart file, then you should know what to do. If that's not the case then a navigator key should help.
You can keep a navigator key for the entire application. Then instead of closing the dialog with Navigator.of(context).pop();, you use navigatorKey.currentState!.pop();.
You should have properly setup the navigator key yourself. Refer to this Stackoverflow answer for how to do that: https://stackoverflow.com/a/72945522/13644299
It is not compulsory to use get_it package. You can simply export the NavigationService (that will keep the navigatorKey) from any Dart file or with any method you deem fit, depending on your current state management architecture.
When clicking on an OPEN LIST button, the app creates a series of lists needed for future display. I found out that when the number of items in the list increases, these calculations can take a little time (2, 3 seconds). So for better UX, I would like to add something similar to a loading indicator telling the user the "lists are being prepared".
In my app, I use the package Loading Indicator : it works fine.
So I wanted to use it for this situation.
Here's what I did :
I transformed my "void" list creating functions into "Future Void".
I added the async keyword to the function plugged to my "OPEN LIST BUTTON".
But... for some reason, it never displays the loading indicator....
Here's the code (UI part) :
onMenuOuvrir: () async {
DialogBuilder(context).showLoadingIndicator(
text: 'Ouverture de la liste', color: Colors.black45);
uD.setSelectedCarnetList(
index, uD.userInfo!.carnetList![index].ref!);
await uD.getListReady();
DialogBuilder(context).hideOpenDialog();
Navigator.pushReplacementNamed(
context, EditCarnetScreen.id);
},
Here's the code (Provider / back end part) :
Future<void> getListReady() async {
await createBufferCarnetWordBank();
await createBufferCarnetList();
await createBufferGrammarList();
await createBufferLevelList();
setEditMode(false);
clearSearchList();
}
The functions "createBuffer...List" are all of type Future .
What am I doing wrong ?
I actually found out that the problem was elsewhere... not in the creation of the lists, but in the building of the "listview.builder" in the EditCarnetScreen.
So here's the question now... how can we display some kind of indicator while this task is being processed.... it seems to be "in between screens"...
Create a widget in a separate dart file :
import 'package:flutter/material.dart';
Loading(BuildContext context) {
return showDialog(
context: context,
barrierDismissible: false,
builder: (BuildContext context) {
return Center(
child: CircularProgressIndicator(
valueColor: AlwaysStoppedAnimation<Color>(Colors.blue),
),
);
});
}
Then use it anywhere in your code:
Loading(context)
Dismiss in whenever you want:
Navigator.of(context).pop()
You can use FutureBuilder widget for that, e.g.
FutureBuilder(future: Provider.of<//your provider>(context)getListReady(), builder: (context, snapshot) => snapshot.connectionState == ConnectionState.waiting ? Center(child: CircularProgressIndicator()) : //your widget)
If you process the calculation in the main thread, even if the indicator shows up the UI freezes and the spinning animation would be laggy.
You may process the heavy lifting tasks by Isolates. Search for Isolate or compute method of dart.
I have used the fluttertoast: ^8.0.8 package as shown below. You can set the toast length to a longer duration if needed. FutureBuilder is not useful in the case, where your widget themselves take a long time render. FutureBuilder is useful while fetching the data required for your widgets.
#override
Widget build(BuildContext context) {
Fluttertoast.showToast(
msg: 'Loading...'
);
//Code for your complex widget here
}
After an action (for example, "save"), user is returned to another page in the app.
I want to show a snackbar on the new page to confirm the action, but don't want it to show if the user navigated there without the action. So for example, if user saves "thing", the app sends them to "things" main page and shows the "saved" snackbar, but if they go to "things" main page some other way, I don't want the "saved" snackbar to be there.
Here is my code on the panel that saves, but the destination page does not show the snackbar — regardless where I place the snackbar (before or after navigation), it does not execute the snackbar.
Future<Null> saveThatThing() async {
thing.save();
thing = new Thing();
Navigator.of(context).push(getSavedThingRoute());
Scaffold.of(context).showSnackBar(
new SnackBar(
content: new Text('You saved the thing!'),
),
);
}
What is the best way to do this?
What about if you create key for the screen Scaffold like this (put this object inside the screen state class):
final GlobalKey<ScaffoldState> scaffoldKey = new GlobalKey<ScaffoldState>();
and then set this variable to the Scaffold key like this:
return new Scaffold(
key: scaffoldKey,
appBar: new AppBar(
.......,
),
and at the end to show the SnackBar just use somewhere inside the screen state class this code :
scaffoldKey.currentState
.showSnackBar(new SnackBar(content: new Text("Hello")));
or you can wrap the latest code in method like this :
void showInSnackBar(String value) {
scaffoldKey.currentState
.showSnackBar(new SnackBar(content: new Text(value)));}
and then just call this method and pass the snack bar message inside.
If you want to show the snack bar message on the next screen, after you navigate away from the initial context, just call the snack bar method on the next screen, not on the first screen.
Hope this will help
You have to return a result to the previous page which will represent the action shown on the page.
In the 1st page When you are navigating to the page change a few things.
bool result=await Navigator.of(context).push(/*Wherever you want*/);
Then in the second page when you are returning to the previous page send some result to the 1st page.
Navigator.of(context).pop(true);
if the work is not success you can return false.
You can return any type of object as result
Then In the 1st page you can check for the result and show the snackBar accordingly
bool result=await Navigator.of(context).push(/*Wherever you want*/);
if(result!=null && result==true){
//Show SnackBar
}else{
//Some other action if your work is not done
}
Since showing SackBar require an active Scaffold, you will need to pass the message to the new route page something like getSavedThingRoute(message: 'You saved the thing!') and the new page is responsible for displaying the message.
Typically I happen to use Navigation.pop({'message': 'You saved the thing!', 'error': false}) to pass the message.
In your 2nd Page's class, override the initState method
#override
void initState() {
super.initState();
// Shows the SnackBar as soon as this page is opened.
Future(() {
final snackBar = SnackBar(content: Text('Hello World'));
ScaffoldMessenger.of(context).showSnackBar(snackBar);
});
}
In case anyone using Flushbar plugin. Put this Inside your build function before return statement.
WidgetsBinding.instance.addPostFrameCallback((timeStamp) {
Flushbar(
message: "Message from the top",
flushbarPosition: FlushbarPosition.TOP,
icon: Icon(
Icons.info_outline,
size: 28.0,
color: Color(0xff00d3fe),
),
flushbarStyle: FlushbarStyle.FLOATING,
duration: Duration(seconds: 5),
)..show(_scaffoldKey.currentState.context);
});}
of course don't forget the scaffold key
final GlobalKey<ScaffoldState> _scaffoldKey = new GlobalKey<ScaffoldState>();
In my case the reason for the snackbar not being shown was the floating action button , I had a logic to put the fab or not and when there was no fab the snack bar did not show , I did not find a proper solution for this but putting a fab like this solved my problem .
however putting Container() , null will cause problems.
Visibility(
visible: false,
child: FloatingActionButton(
onPressed: () {},
),
);
In android version, Flutter TextEditingController does not scroll above keyboard like default text fields do when you start typing in field. I tried to look in sample apps provided in flutter example directory, but even there are no example of TextEditController with such behaviour.
Is there any way to implement this.
Thanks in advance.
so simple
if your textfields is between 5-10 fields
SingleChildScrollView(
reverse: true, // add this line in scroll view
child: ...
)
(August 20, 2021 Flutter 2.2.3)
I think my answer might be the cleanest solution for this problem:
#override
Widget build(BuildContext context) {
/// Get the [BuildContext] of the currently-focused
/// input field anywhere in the entire widget tree.
final focusedCtx = FocusManager.instance.primaryFocus!.context;
/// If u call [ensureVisible] while the keyboard is moving up
/// (the keyboard's display animation does not yet finish), this
/// will not work. U have to wait for the keyboard to be fully visible
Future.delayed(const Duration(milliseconds: 400))
.then((_) => Scrollable.ensureVisible(
focusedCtx!,
duration: const Duration(milliseconds: 200),
curve: Curves.easeIn,
));
/// [return] a [Column] of [TextField]s here...
}
Every time the keyboard kicks in or disappears, the Flutter framework will automatically call the build() method for u. U can try to place a breakpoint in the IDE to figure out this behavior yourself.
Future.delayed() will first immediately return a pending Future that will complete successfully after 400 milliseconds. Whenever the Dart runtime see a Future, it will enter a non-blocking I/O time (= inactive time = async time = pending time, meaning that the CPU is idle waiting for something to complete). While Dart runtime is waiting for this Future to complete, it will proceed to the lines of code below to build a column of text fields. And when the Future is complete, it will immediately jump back to the line of code of this Future and execute .then() method.
More about asynchronous programming from this simple visualization about non-blocking I/O and from the Flutter team.
Flutter does not have such thing by default.
Add your TextField in a ListView.
create ScrollController and assign it to the ListView's controller.
When you select the TextField, scroll the ListView using:
controller.jumpTo(value);
or if you wish to to have scrolling animation:
controller.animateTo(offset, duration: null, curve: null);
EDIT: Of course the duration and curve won't be null. I just copied and pasted it here.
Thank you all for the helpful answers #user2785693 pointed in the right direction.
I found complete working solution here:
here
Issue with just using scroll or focusNode.listner is, it was working only if I focus on textbox for the first time, but if I minimize the keyboard and again click on same text box which already had focus, the listner callback was not firing, so the auto scroll code was not running. Solution was to add "WidgetsBindingObserver" to state class and override "didChangeMetrics" function.
Hope this helps others to make Flutter forms more user friendly.
This is an attempt to provide a complete answer which combines information on how to detect the focus from this StackOverflow post with information on how to scroll from Arnold Parge.
I have only been using Flutter for a couple days so this might not be the best example of how to create a page or the input widget.
The link to the gist provided in the other post also looks like a more robust solution but I haven't tried it yet. The code below definitely works in my small test project.
import 'package:flutter/material.dart';
class MyPage extends StatefulWidget {
#override createState() => new MyPageState();
}
class MyPageState extends State<MyPage> {
ScrollController _scroll;
FocusNode _focus = new FocusNode();
#override void initState() {
super.initState();
_scroll = new ScrollController();
_focus.addListener(() {
_scroll.jumpTo(-1.0);
});
}
#override Widget build(BuildContext context) {
return new Scaffold(
appBar: new AppBar(
title: new Text('Some Page Title'),
),
body: new DropdownButtonHideUnderline(
child: new SafeArea(
top: false,
bottom: false,
child: new ListView(
controller: _scroll,
padding: const EdgeInsets.all(16.0),
children: <Widget>[
// ... several other input widgets which force the TextField lower down the page ...
new TextField(
decoration: const InputDecoration(labelText: 'The label'),
focusNode: _focus,
),
],
),
),
),
);
}
}