This seems like a bug, but I wanted to solicit feedback first. In my simple demo app below, you can see where the SliverChildBuilderDelegate is generating Text widgets as the SliverList. When you scroll up the text widgets overlap with the header. If you wrap the Text widget in a Material widget then that solves the problem (perhaps it's because of Material's clipping capability?). Mixing Material and Cupertino widgets isn't the best, however, particularly if you want to use a CupertinoTheme.
Any suggestions about what's going on and what to do about it is appreciated.
thanks
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
// This widget is the root of your application.
#override
Widget build(BuildContext context) {
return CupertinoApp(
title: 'Cupertino Demo',
home: MyHomePage(),
);
}
}
class MyHomePage extends StatelessWidget {
#override
Widget build(BuildContext context) {
return CupertinoPageScaffold(
child: SafeArea(
child: CustomScrollView(
shrinkWrap: true,
slivers: [
CupertinoSliverNavigationBar(
largeTitle: Text('Cupertino Demo'),
),
SliverList(
delegate: SliverChildBuilderDelegate(
(_, index) => Material(child: Text('This is list item number $index')),
),
)
],
),
),
);
}
}
Because of the shrinkWrap:true, you can read more here:
https://github.com/flutter/flutter/issues/28197
I don't see why would you need that, so simply just remove and it will work.
I am trying to change shadow elevation color of the AppBar but can't find any property for that.
I went to the original implementation as well but cant find any property to change shadow color.
AppBar(
title: Image.asset(
"images/toolbar_logo.webp",
width: 80,
height: 50,
),
centerTitle: true,
backgroundColor: white,
),
I cant wrap the AppBar inside a Material Widget.
I know i can avoid the app bar property and create a custom class and add it to my body of Scaffold,
but is it possible to change using shadow color of AppBar?
There isn't a way to change the colour of the default shadow but you can get around it by wrapping your AppBar in a Container which is inside a PreferredSize widget:
void main() => runApp(App());
class App extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
appBar: PreferredSize(
child: Container(
decoration: BoxDecoration(boxShadow: [
BoxShadow(
color: Colors.red,
offset: Offset(0, 2.0),
blurRadius: 4.0,
)
]),
child: AppBar(
elevation: 0.0,
title: Text("Test"),
),
),
preferredSize: Size.fromHeight(kToolbarHeight),
),
body: Container(),
),
);
}
}
The accepted answer is a bit expired. You can do this in two ways:
Changing directly through the AppBar property:
void main() => runApp(App());
class App extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
appBar: AppBar(shadowColor: Colors.green),
body: Container(),
),
);
}
}
Or by using the Theme:
void main() => runApp(App());
class App extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
theme: ThemeData(
appBarTheme: AppBarTheme(
shadowColor: Colors.white,
),
),
home: Scaffold(
appBar: AppBar(),
body: Container(),
),
);
}
}
You can use the shadowColor property of Appbar to color to paint the shadow below the app bar.
For color, I can use dialogBackgroundColor property to give AlertDialog background my own color.
I was looking to use Gradient as my background. How can I use that? DecoratedBox is something that will be needed, but I don't know what to wrap in what. Can anyone give me idea or link for the same?
You can add a Container inside which will be decorated with gradient. For example:
class GradientDialog extends StatefulWidget {
#override
State<StatefulWidget> createState() {
return new _GradientDialogState();
}
}
class _GradientDialogState extends State<GradientDialog> {
#override
Widget build(BuildContext context) {
return AlertDialog(
content: Container(
padding: const EdgeInsets.all(8.0),
decoration: new BoxDecoration(
gradient: new LinearGradient(
colors: AppColors.BG_GRADIENT,
begin: Alignment.topCenter,
end: Alignment.bottomCenter)),
child: YourContentInside(),
),
contentPadding: EdgeInsets.all(0.0),
);
}
}
Open it with
showDialog(
context: context,
barrierDismissible: true,
builder: (BuildContext context) {
return GradientDialog();
});
In build method of AlertDialog there is return Dialog(child: dialogChild, shape: shape);. In Dialog.build() - it returns Material(color: _getColor(context), .... There is no way to set gradient background for AlertDialog without customization.
I can add example if it'll be needed.
P.S. Or you can call showDialog and send another widget instead of AlertDialog.
I am trying to change the color of the element the user clicked on using a GestureDetector:
new GestureDetector(
onTap: (){
// Change the color of the container beneath
},
child: new Container(
width: 80.0,
height: 80.0,
margin: new EdgeInsets.all(10.0),
color: Colors.orange,
),
),
The problem is that I can't use setState inside of onTap. Otherwise I would have created a color variable. Any suggestions?
You can use setState() inside of onTap. In fact, that's exactly the right thing to do in this situation. If you are having trouble calling setState(), make sure your widget is stateful (see the interactivity tutorial).
You might also want to check out FlatButton or InkWell as more material-y ways to capture touches. If you really want a GestureDetector, read up on HitTestBehavior to make sure you're configuring it correctly.
Here's an example that changes to a random color every time it's clicked.
import 'dart:math';
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',
home: new MyHome(),
);
}
}
class MyHome extends StatefulWidget {
#override
State createState() => new _MyHomeState();
}
class _MyHomeState extends State<MyHome> {
final Random _random = new Random();
Color _color = Colors.orange;
#override
Widget build(BuildContext context) {
return new Scaffold(
body: new Center(
child: new GestureDetector(
onTap: () {
// Change the color of the container beneath
setState(() {
_color = new Color.fromRGBO(
_random.nextInt(256),
_random.nextInt(256),
_random.nextInt(256),
1.0
);
});
},
child: new Container(
width: 80.0,
height: 80.0,
margin: new EdgeInsets.all(10.0),
color: _color,
),
),
),
);
}
}
I'm learning Flutter, and I'm starting from the very basics. I'm not using MaterialApp. What's a good way to set the background color of the whole screen?
Here's what I have so far:
import 'package:flutter/material.dart';
void main() {
runApp(new MyApp());
}
class MyApp extends StatelessWidget {
// This widget is the root of your application.
#override
Widget build(BuildContext context) {
return new Center(child: new Text("Hello, World!"));
}
}
Some of my questions are:
What's a basic way to set the background color?
What exactly am I looking at, on the screen? Which code "is" the background? Is there a thing to set the background color on? If not, what's a simple and appropriate "simple background" (in order to paint a background color).
Thanks for the help!
The code above generates a black screen with white text:
You can set background color to All Scaffolds in application at once.
Just set scaffoldBackgroundColor: in ThemeData:
MaterialApp(
title: 'Flutter Demo',
theme: new ThemeData(scaffoldBackgroundColor: const Color(0xFFEFEFEF)),
home: new MyHomePage(title: 'Flutter Demo Home Page'),
);
I think you can also use a scaffold to do the white background. Here's some piece of code that may help.
import 'package:flutter/material.dart';
void main() => runApp(new MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return new MaterialApp(
title: 'Testing',
home: new Scaffold(
//Here you can set what ever background color you need.
backgroundColor: Colors.white,
),
);
}
}
Here's one way that I found to do it. I don't know if there are better ways, or what the trade-offs are.
Container "tries to be as big as possible", according to https://flutter.io/layout/. Also, Container can take a decoration, which can be a BoxDecoration, which can have a color (which, is the background color).
Here's a sample that does indeed fill the screen with red, and puts "Hello, World!" into the center:
import 'package:flutter/material.dart';
void main() {
runApp(new MyApp());
}
class MyApp extends StatelessWidget {
// This widget is the root of your application.
#override
Widget build(BuildContext context) {
return new Container(
decoration: new BoxDecoration(color: Colors.red),
child: new Center(
child: new Text("Hello, World!"),
),
);
}
}
Note, the Container is returned by the MyApp build(). The Container has a decoration and a child, which is the centered text.
See it in action here:
There are many ways of doing it, I am listing few here.
Using backgroundColor
Scaffold(
backgroundColor: Colors.black,
body: Center(...),
)
Using Container in SizedBox.expand
Scaffold(
body: SizedBox.expand(
child: Container(
color: Colors.black,
child: Center(...)
),
),
)
Using Theme
Theme(
data: Theme.of(context).copyWith(scaffoldBackgroundColor: Colors.black),
child: Scaffold(
body: Center(...),
),
)
You should return Scaffold widget and add your widget inside Scaffold
Such as this code:
import 'package:flutter/material.dart';
void main() {
runApp(new MyApp());
}
class MyApp extends StatelessWidget {
// This widget is the root of your application.
#override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Colors.white,
body: Center(child: new Text("Hello, World!"));
);
}
}
Scaffold(
backgroundColor: Constants.defaulBackground,
body: new Container(
child: Center(yourtext)
)
)
It's another approach to change the color of background:
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(home: Scaffold(backgroundColor: Colors.pink,),);
}
}
On the basic example of Flutter you can set with backgroundColor: Colors.X of Scaffold
#override
Widget build(BuildContext context) {
// This method is rerun every time setState is called, for instance as done
// by the _incrementCounter method above.
//
// The Flutter framework has been optimized to make rerunning build methods
// fast, so that you can just rebuild anything that needs updating rather
// than having to individually change instances of widgets.
return Scaffold(
backgroundColor: Colors.blue,
body: Center(
// Center is a layout widget. It takes a single child and positions it
// in the middle of the parent.
child: Column(
// Column is also layout widget. It takes a list of children and
// arranges them vertically. By default, it sizes itself to fit its
// children horizontally, and tries to be as tall as its parent.
//
// Invoke "debug painting" (press "p" in the console, choose the
// "Toggle Debug Paint" action from the Flutter Inspector in Android
// Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
// to see the wireframe for each widget.
//
// Column has various properties to control how it sizes itself and
// how it positions its children. Here we use mainAxisAlignment to
// center the children vertically; the main axis here is the vertical
// axis because Columns are vertical (the cross axis would be
// horizontal).
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'You have pushed the button this many times:',
),
Text(
'$_counter',
style: Theme.of(context).textTheme.display1,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add_circle),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
I think you need to use MaterialApp widget and use theme and set primarySwatch with color that you want. look like below code,
import 'package:flutter/material.dart';
void main() {
runApp(new MyApp());
}
class MyApp extends StatelessWidget {
// This widget is the root of your application.
#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'),
);
}
}
home: Scaffold(
backgroundColor: Color(
0xBF453F3F),
and done :)
You can just put the six digit hexa after (0xFF**......**):
return Scaffold(
backgroundColor: const Color(0xFFE9ECEF),
.....) } )
import 'package:flutter/material.dart';
void main() {
runApp(new MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Your App',
theme: ThemeData(
scaffoldBackgroundColor: Colors.black,
),
home HomeScreen(),
);
}
}
Sample code:
import 'package:flutter/material.dart';
void main() {
runApp(
MaterialApp(
home: Scaffold(
appBar: AppBar(
title: Text('Sample App'),
backgroundColor: Colors.amber, // changing Appbar back color
),
backgroundColor: Colors.blue, // changing body back color
),
),
);
}
As sirelon suggested, add scaffold color in the theme like this,
theme: new ThemeData(scaffoldBackgroundColor: const Color(0xFFEFEFEF)),
or can give color to individual scaffold like this
Scaffold(
backgroundColor: Color(0xFFF1F1F1),
...
);
Try the following code:
import 'package:flutter/material.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({super.key});
#override
Widget build(BuildContext context) {
return MaterialApp(
theme: ThemeData(
scaffoldBackgroundColor: Colors.white, // Change the background color of all Scaffold widgets of your app here
),
home: const Scaffold(
body: Center(child: Text("Hello, World!")),
backgroundColor: Colors.white, // Change the background color of this Scaffold widget here
),
);
}
}