CircularProgressIndicator not displayed in flutter - dart

Im trying to display the CircularProgressIndicator in my flutter app on click of button but it does not render the circular progress bar, but as soon as I change the code to use LinearProgressBar the progress bar comes without any issue. So wanted to know is there any special setting which I need to display the circular loading indicator?
Works
if (_isFetching) {
return new Scaffold(
body: new Center(
child: new SizedBox(
width: 40.0,
height: 40.0,
child: const LinearProgressIndicator(backgroundColor: Colors.black)),
));
}
Do not work
if (_isFetching) {
return new Scaffold(
body: new Center(
child: new SizedBox(
width: 40.0,
height: 40.0,
child: const CircularProgressIndicator(backgroundColor: Colors.black)),
));
}

Make sure the progress bar's value color is different from the parent widget's background color. Try this:
if (_isFetching) {
return Scaffold(
body: Center(
child: SizedBox(
width: 40.0,
height: 40.0,
child: const CircularProgressIndicator(
backgroundColor: Colors.black,
valueColor: AlwaysStoppedAnimation<Color>(Colors.red))),
));
}

You can refer to the docs here. You are using backgroundColor property which only defines background color of indicator and not the type of indicator. I'm using null for Indeterminate type. You can use valueColor[doc] property to change the color of indicator. Here is simple code and it works fine.
if (_isFetching) {
return new Scaffold(
body: new Center(
child: new SizedBox(
width: 40.0,
height: 40.0,
child:
const CircularProgressIndicator(
value: null,
strokeWidth: 2.0,
)),
));
}

Related

List tile with vertical line and image

I am trying to create a listview with an image and vertical line at the start of the list tile. I will try to explain with an image.
I have tried using a stack with a container for the vertical line, and then an image right after, but it didn't work. I also tried adding a Position.fill to the vertical line, which also didn't work.
Row(
children: <Widget>[
Stack(
children: <Widget>[
new Image(image: new AssetImage("assets/img/airplane.png")),
Positioned.fill(
child: Container(
height: 1.0,
width: 3.0,
color: Colors.green,
margin: const EdgeInsets.only(left: 30.0, right: 10.0),
),
),
],
)
],
),
This is what i am trying to achieve.
An example of an app on the store that does what I am trying to achieve:
Here an example:
class MainPageState extends State<MainPage> {
//State must have "build" => return Widget
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Stack(alignment: const Alignment(0.0, 0.0), children: <Widget>[
Container(
//Do you need to make Image as "Circle"
child: Image.asset('images/sanBernardo1.jpg',
width: 150.0, height: 150.0, fit: BoxFit.fill),
),
Positioned(
left: 50.0,
child: Container(
width: 12.0,
height: 100.0,
padding: const EdgeInsets.all(5.0),
decoration: BoxDecoration(color: Colors.red[400])),
)
]));
}
}
Hope this help.
The correct widget for this case is Stepper
https://api.flutter.dev/flutter/material/Stepper-class.html
So, you can create progress through a sequence of steps with a lot of built-in functionality.
Also, it could be useful take a look to Material style guide https://material.io/archive/guidelines/components/steppers.html#

Anchor floating action button to Card

When creating a Card (for example using the code from the Docs) , how can I anchor a FAB to the Card (the green circle in the image below), like in this question for Android.
I saw a similar question for attaching a FAB to the AppBar, but the solution relies on the AppBar being a fixed height. When using a Card, the height isn't fixed ahead of time so the same solution can't be used.
You can place the FloatingActionButton in an Align widget and play with the heightFactor property.
For example:
class MyCard extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Card(
child: Column(
children: <Widget>[
SizedBox(height: 100.0, width: double.infinity),
Align(
alignment: Alignment(0.8, -1.0),
heightFactor: 0.5,
child: FloatingActionButton(
onPressed: null,
child: Icon(Icons.add),
),
)
],
),
);
}
}
Correct solution for anchor FAB.
Another solution using stack and container. FAB's place is based on its sibling Container widget's size and clicks/taps work properly.
import 'package:flutter/material.dart';
void main() {
runApp(
MaterialApp(
home: MyWidget(),
),
);
}
class MyWidget extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Scaffold(
body: Stack(
children: <Widget>[
Container(
padding: EdgeInsets.only(bottom: 28),
child: Container(
width: double.infinity,
height: 150,
color: Color.fromRGBO(55, 55, 55, 0.2),
padding: EdgeInsets.all(15),
child: Text(
'Any container with bottom padding with half size of the FAB'),
),
),
Positioned(
bottom: 0,
right: 10,
child: FloatingActionButton(
child: Icon(
Icons.play_arrow,
size: 40,
),
onPressed: () => print('Button pressed!'),
),
),
],
),
);
}
}
CodePan link for anchor FAB
The correct solution is to use a "Stack" and "Positioned" widged like:
return Stack(
children: <Widget>[
Card(
color: Color(0xFF1D3241),
margin: EdgeInsets.only(bottom: 40), // margin bottom to allow place the button
child: Column(children: <Widget>[
...
],
),
Positioned(
bottom: 0,
right: 17,
width: 80,
height: 80,
child: FloatingActionButton(
backgroundColor: Color(0xFFF2638E),
child: Icon(Icons.play_arrow,size: 70,)
),
),
],
);

How to overlay a view partially using the Stack widget in Flutter

I am using Flutter for my app development.
I would like to overlay a poster image view on top of a background image just like in this screenshot below.
The code snippet below does this, but it requires me to also position every other widget including the movie title, release date, etc based on poster's position and background image's position, which is not reliable across several devices and orientation. Is there an example or suggestion to solve this problem?
#override
Widget build(BuildContext context) {
return new Scaffold(
appBar: new PlatformAdaptiveAppBar(
title: new Text(widget.movie.title),
),
body: new Container(
constraints: new BoxConstraints.expand(),
child: new Stack(
children: <Widget>[
new Container(
child: new Image(
image: new AdvancedNetworkImage(
movieGridUtil.getUrlFromPath(widget.movie.backdrop_path,
MovieGridImageTypes.BACKDROP),
useMemoryCache: false,
useDiskCache: true)),
constraints: new BoxConstraints.expand(height: 250.0),
),
new Positioned(
left: 12.0,
top: 220.0,
child: new Image(
width: 100.0,
height: 150.0,
image: new AdvancedNetworkImage(
movieGridUtil.getUrlFromPath(widget.movie.poster_path,
MovieGridImageTypes.POSTER),
useMemoryCache: false,
useDiskCache: true),
)),
],
)),
);
}
Create Stack
Then inside Stack add Column and make full layout without the poster.
Then as a second Child of Stack, add this combination:
new Stack(
children: [
new Column(
children: _layout()
new Positioned(
top:200,
left:50,
child: _child // or optionaly wrap the child in FractionalTranslation
)]
)
)
Stack(
children: <Widget>[
Container(
color: Colors.blue,
height: 200.0,
),
Padding(
padding: const EdgeInsets.only(left: 20.0,right: 20.0, top:160.0),
child: Container(
color: Colors.pink,
height: 150.0,
width: 110.0,
),
)
],
),
By Creating the Stack,
You can add multiple Container, whichever is last added will be on the top.
Stack(
children: <Widget>[
Container(
color: Colors.blue,
height: 200.0,
),
Padding(
padding: const EdgeInsets.only(left: 20.0,right: 20.0, top:160.0),
child: Container(
color: Colors.pink,
height: 150.0,
width: 110.0,
),
)
],
),

Flutter position fixed equivalent

Is it possible to fix an object in the screen that stays fixed regardless of scrolling?
Something similar to CSS position fixed.
You can absolutely position a child of a Stack widget using the Positioned widget.
The minimal example below places the red box above the list view, by placing the child in a Positioned widget after the ListView in the Stack's children.
List<String> todos = [...];
return new Stack(
children: <Widget>[
new ListView(
children: todos
.map((todo) => new ListTile(title: new Text(todo)))
.toList(),
),
new Positioned(
left: 30.0,
top: 30.0,
child: new Container(
width: 100.0,
height: 80.0,
decoration: new BoxDecoration(color: Colors.red),
child: new Text('hello'),
)
),
],
);
And here it is inside of a Scaffold body. If you add more items you'll find that the list scrolls without moving the red box.
You could use Positioned widget in a Stack Widget with AspectRatio widget and use the % distance like the below code.
#override
Widget build(BuildContext context) {
Size size = MediaQuery.of(context).size; //get the screen size
List<String> todos = [...];
//the below if to get the aspect ratio of the screen i am using the app only in landscape
//if you need to use it in portrait you should add the sizes below
if((size.width / size.height) > 1.76){
aspect = 16 / 9;
}else if((size.width / size.height) < 1.77 && (size.width / size.height) >= 1.6){
aspect = 16 / 10;
}else{
aspect = 4 /3;
}
return new Scaffold(
body: new Center(
//layoutBuilder i can use the constraints to get the width and height of the screen
child: new LayoutBuilder(builder: (context, constraints) {
return new AspectRatio(
aspectRatio: aspect,
child: new Column(
children: <Widget>[
new ListView(
children: todos
.map((todo) => new ListTile(title: new Text(todo)))
.toList(),
),
new Positioned(
//constraints.biggest.height to get the height
// * .05 to put the position top: 5%
top: constraints.biggest.height * .05,
left: constraints.biggest.width * .30,
child: new Container(
width: 100.0,
height: 80.0,
decoration: new BoxDecoration(color: Colors.red),
child: new Text('hello'),
),
),
],
),
),
}),
),
);
}
}
Hope it will help you....
I prefer this solution:
Stack(
children: [
Column(
children: [
Container(...),
Container(...),
]
),
Positioned(top:50, child: Card(...))
]
)
Widget build(BuildContext context) {
return Column(
children: [
Container(
// covers 20% of total height
height: 200,
child: Stack(
children: [
Container(
height: 300,
decoration: BoxDecoration(
color: Colors.red,
),
),
Positioned(
bottom: 0,
left: 0,
width: 100,
height: 100,
child: Container(
height: 54,
decoration: BoxDecoration(
color: Colors.blue,
),
),
)
],
),
),
],
);
}
Adding a width and height to your Positioned widget will make it appear if you want to use top/left/bottom/right

How to show fullscreen image in flutter

Is there any way to show fullscreen image ?
var imagejadwal = new Image.network(
"https://firebasestorage.googleapis.com/v0/b/c-smp-bruder.appspot.com/o/fotojadwal.jpg?alt=media&token=b35b74df-eb40-4978-8039-2f1ff2565a57",
fit: BoxFit.cover
);
return new Scaffold(
appBar: new AppBar(
title: new Text(widget.title),
),
body: new Center(
child: imagejadwal
),
);
in that code, there's space around the image :/
Your problem is that Center will make the image to get it's preferred size instead of the full size.
The correct approach would be instead to force the image to expand.
return new Scaffold(
body: new Image.network(
"https://cdn.pixabay.com/photo/2017/02/21/21/13/unicorn-2087450_1280.png",
fit: BoxFit.cover,
height: double.infinity,
width: double.infinity,
alignment: Alignment.center,
),
);
The alignment: Alignment.center is unnecessary. But since you used the Center widget, I tought it would be interesting to know how to customize it.
Here is a View you wrap around your image widget
Includes a click event which opens up a full screen view of the image
Zoom and Pan image
Null-safety
Dark/Light background for PNGs
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
class ImageFullScreenWrapperWidget extends StatelessWidget {
final Image child;
final bool dark;
ImageFullScreenWrapperWidget({
required this.child,
this.dark = true,
});
#override
Widget build(BuildContext context) {
return GestureDetector(
onTap: () {
Navigator.push(
context,
PageRouteBuilder(
opaque: false,
barrierColor: dark ? Colors.black : Colors.white,
pageBuilder: (BuildContext context, _, __) {
return FullScreenPage(
child: child,
dark: dark,
);
},
),
);
},
child: child,
);
}
}
class FullScreenPage extends StatefulWidget {
FullScreenPage({
required this.child,
required this.dark,
});
final Image child;
final bool dark;
#override
_FullScreenPageState createState() => _FullScreenPageState();
}
class _FullScreenPageState extends State<FullScreenPage> {
#override
void initState() {
var brightness = widget.dark ? Brightness.light : Brightness.dark;
var color = widget.dark ? Colors.black12 : Colors.white70;
SystemChrome.setEnabledSystemUIOverlays([SystemUiOverlay.top]);
SystemChrome.setSystemUIOverlayStyle(SystemUiOverlayStyle(
systemNavigationBarColor: color,
statusBarColor: color,
statusBarBrightness: brightness,
statusBarIconBrightness: brightness,
systemNavigationBarDividerColor: color,
systemNavigationBarIconBrightness: brightness,
));
super.initState();
}
#override
void dispose() {
SystemChrome.setEnabledSystemUIOverlays(SystemUiOverlay.values);
SystemChrome.setSystemUIOverlayStyle(SystemUiOverlayStyle(
// Restore your settings here...
));
super.dispose();
}
#override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: widget.dark ? Colors.black : Colors.white,
body: Stack(
children: [
Stack(
children: [
AnimatedPositioned(
duration: Duration(milliseconds: 333),
curve: Curves.fastOutSlowIn,
top: 0,
bottom: 0,
left: 0,
right: 0,
child: InteractiveViewer(
panEnabled: true,
minScale: 0.5,
maxScale: 4,
child: widget.child,
),
),
],
),
SafeArea(
child: Align(
alignment: Alignment.topLeft,
child: MaterialButton(
padding: const EdgeInsets.all(15),
elevation: 0,
child: Icon(
Icons.arrow_back,
color: widget.dark ? Colors.white : Colors.black,
size: 25,
),
color: widget.dark ? Colors.black12 : Colors.white70,
highlightElevation: 0,
minWidth: double.minPositive,
height: double.minPositive,
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(100),
),
onPressed: () => Navigator.of(context).pop(),
),
),
),
],
),
);
}
}
Example Code:
ImageFullScreenWrapperWidget(
child: Image.file(file),
dark: true,
)
This is another option:
return new DecoratedBox(
decoration: new BoxDecoration(
image: new DecorationImage(
image: new AssetImage('images/lake.jpg'),
fit: BoxFit.fill
),
),
);
For Image from asset
new Image(
image: AssetImage('images/test.jpg'),
fit: BoxFit.cover,
height: double.infinity,
width: double.infinity,
alignment: Alignment.center,
),
For some reason, the solutions given in the answers here did not work for me. The below code worked for me.
body: Container(
height: double.infinity,
width: double.infinity,
child: FittedBox(child: Image.asset('assets/thunderbackground.jpg'),
fit: BoxFit.cover),
you could try wrapping image.network in a a container with infinite dimensions which takes the available size of its parent (meaning if you drop this container in lower half of screen it will fill the lower half of screen if you put this directly as the body of scaffold it will take the full screen)
Container(
height: double.infinity,
width: double.infinity,
child: Image.network(
backgroundImage1,
fit: BoxFit.cover,
)
);
You can use MediaQuery class if you want to get the precious size of your device and use it to manage the size of your image, here's the examples:
return Container(
color: Colors.white,
child: Image.asset(
'assets/$index.jpg',
fit: BoxFit.fill,
height: MediaQuery.of(context).size.height,
width: MediaQuery.of(context).size.width,
alignment: Alignment.center,
),
);
Here is an example of a FadeInImage with another widget overlay using the double.infinity method as in the accepted answer.
class FullScreenImage extends StatelessWidget {
#override
Widget build(BuildContext context) {
//you do not need container here, STACK will do just fine if you'd like to
//simplify it more
return Container(
child: Stack(children: <Widget>[
//in the stack, the background is first. using fit:BoxFit.cover will cover
//the parent container. Use double.infinity for height and width
FadeInImage(
placeholder: AssetImage("assets/images/blackdot.png"),
image: AssetImage("assets/images/woods_lr_50.jpg"),
fit: BoxFit.cover,
height: double.infinity,
width: double.infinity,
//if you use a larger image, you can set where in the image you like most
//width alignment.centerRight, bottomCenter, topRight, etc...
alignment: Alignment.center,
),
_HomepageWords(context),
]),
);
}
}
//example words and image to float over background
Widget _HomepageWords(BuildContext context) {
return Column(
mainAxisAlignment: MainAxisAlignment.start,
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
InkWell(
child: Padding(
padding: EdgeInsets.all(30),
child: Column(
mainAxisAlignment: MainAxisAlignment.start,
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Padding(
padding: EdgeInsets.fromLTRB(0, 40, 0, 12),
child: Image.asset(
"assets/images/Logo.png",
height: 90,
semanticLabel: "Logo",
),
),
Text(
"ORGANIZATION",
style: TextStyle(
fontSize: 24,
fontWeight: FontWeight.bold,
color: Colors.white),
),
Text(
"DEPARTMENT",
style: TextStyle(
fontSize: 50,
fontWeight: FontWeight.bold,
color: Colors.white),
),
Text(
"Disclaimer information...",
style: TextStyle(
fontSize: 12,
fontWeight: FontWeight.bold,
color: Colors.white),
),
],
),
),
onTap: () {
//to another screen / page or action
},
),
],
);
}
Use the below code if height: double.infinity, width: double.infinity, doesn't work to u.
class SplashScreen extends StatefulWidget {
#override
_SplashScreenState createState() => new _SplashScreenState();
}
class _SplashScreenState extends State<SplashScreen> {
#override
void initState() {
super.initState();
Timer(Duration(seconds: 30),()=>Navigator.push(
context, MaterialPageRoute(builder: (context)=>Login())));
}
#override
Widget build(BuildContext context) {
return new Scaffold(
//backgroundColor: Colors.white,
body: Container(
child: new Column(children: <Widget>[
new Image.asset(
'assets/image/splashScreen.png',
fit: BoxFit.fill,
// height: double.infinity,
// width: double.infinity,
width: MediaQuery.of(context).size.width,
height: MediaQuery.of(context).size.height,
alignment: Alignment.center,
repeat: ImageRepeat.noRepeat,
),
]),
),
);
}
}

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