When I use a regular AppBar in a Scaffold, all of the content is pushed down so it's not covered. However, now that I created a custom FloatingAppBar, the content goes under the app bar even though I'm using it the same way. Also, since the FloatingAppBar has to implement PreferredSizeWidget, I also have to give it a preferred size from the height which makes the height of the app bar very small when I use it in a bottom modal widget. Is there any way to get around that? Here is a screenshot of the issue and the code for the custom app bar:
import 'package:flutter/material.dart';
class FloatingAppBar extends StatelessWidget implements PreferredSizeWidget {
const FloatingAppBar(
{Key? key,
required this.title,
required this.leading,
required this.actions})
: super(key: key);
final Widget leading;
final Widget title;
final List<Widget> actions;
#override
Widget build(BuildContext context) {
return Padding(
padding: const EdgeInsets.all(40),
child: ClipRRect(
borderRadius: BorderRadius.circular(40),
child: Container(
color: const Color(0xFFd3d8e9),
height: 120,
child: Center(
child: Padding(
padding: const EdgeInsets.symmetric(horizontal: 15),
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
leading,
title,
Row(
children: actions,
)
],
),
),
),
),
),
);
}
#override
Size get preferredSize => const Size.fromHeight(120);
}
The reason of this issue is that you set the appbar height 120, but the actual height you give to appbar is 120 + padding top + padding bottom. in order to fix it , you could do this:
Size get preferredSize => const Size.fromHeight(120 + 40 + 40);
For your color issue, because you know the app bar height 120 in this case, you can add top padding to your scaffold body to fix the background color issue.
I have a Text widget that sometimes can be fully displayed, sometimes not, depending on the widgets around.
If there is not enough space to fully display the widget, I want the widget to not show at all, I don't want it to show partially like with the overflow attribute.
If you know a way to do this, thanks.
LayoutBuilder to the rescue for you!
Builds a widget tree that can depend on the parent widget's size.
Reference
Try this! Play around with the allowedTextHeightInPixels value to see how it works.
/// Breakpoint or condition to WHEN should we display the Text widget
const allowedTextHeightInPixels = 150.0;
/// Test height for the [Text] widget.
const givenTextHeightByScreenPercentage = 0.3;
class ResponsiveTextWidget extends StatelessWidget {
const ResponsiveTextWidget({Key? key}) : super(key: key);
#override
Widget build(BuildContext context) {
return Scaffold(
body: SafeArea(
child: LayoutBuilder(
builder: (context, constraints) {
print('Text height in pixels: ${constraints.maxHeight * givenTextHeightByScreenPercentage}');
return Column(
children: [
Container(
color: Colors.red,
height: constraints.maxHeight * 0.5,
),
if (constraints.maxHeight * givenTextHeightByScreenPercentage > allowedTextHeightInPixels)
const SizedBox(
child: Text(
'Responsive Me',
style: TextStyle(fontSize: 15.0),
),
),
Container(
color: Colors.blue,
height: constraints.maxHeight * 0.2,
),
],
);
},
),
),
);
}
}
I don't know why you need to do this but i thing overflow is good enough for most case, you can also use Fittedbox to scale the text with the box with no redundant space.
In case you still want do it, you need to find the RenderBox of that specific widget, which will contain its global position and rendered size from BuildContext. But BuildContext can be not exist if the widget is not rendered yet.
If by "fully displayed" you mean that, for example, you have a SingleChildScrollView and only half of your Text widget is visible, you can try out this library :
https://pub.dev/packages/visibility_detector.
You can retrieve the visible percentage of your widget with the method visibilityInfo.visibleFraction.
I have a Flutter Web application where I need to show a widget on the right side of a ListView when I click an item and this widget should always be visible on screen. I can achieve my objective puting both on a Row and using a scrollable only for the ListView, but that requires the ListView to be wrapped by a widget with defined height.
Defining a container with height to wrap the ListView breaks the responsiveness when I resize the browser, as the container doesn't fit the height of the screen.
I thought of using the shrinkWrap property of the ListView so I don't have to wrap it in a widget with predefined height, but that makes the whole Row scrollable vertically, eventually causing the widget to leave the viewport.
I would appreciate if somebody knows how could I keep this right side widget fixed on screen so I can achieve my objective without losing responsiveness.
Here's something similitar to what I've got so far:
class PageLayout extends StatefulWidget {
const PageLayout({Key? key, required this.items}) : super(key: key);
final List<String> items;
#override
State<PageLayout> createState() => _PageLayoutState();
}
class _PageLayoutState extends State<PageLayout> {
final rightSideWidget = Container(
decoration: BoxDecoration(
color: Colors.red,
border: Border.all(color: Colors.white, width: 2),
),
height: 200);
#override
Widget build(BuildContext context) {
return Scaffold(
body: SingleChildScrollView(
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
crossAxisAlignment: CrossAxisAlignment.start,
children: [
SizedBox(
width: MediaQuery.of(context).size.width * 0.49,
child: ListView.builder(
shrinkWrap: true,
itemBuilder: (context, index) => Container(
decoration: BoxDecoration(
color: Colors.blue,
border: Border.all(color: Colors.white, width: 2),
),
height: 200,
child: Center(
child: Text(
widget.items[index],
style: const TextStyle(color: Colors.white),
),
),
),
itemCount: widget.items.length,
),
),
Expanded(child: rightSideWidget),
],
),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
}
I want rightSideWidget to be always centered on screen or follow the scroll.
You can divide your screen into two sections, right section and left section; thereby being able to control behaviour of widgets in both sections.
Divide the overall screen into 2 proportional sections using a Row
widget
Put this Row widget inside a Container with height equal to screen height for preserving responsiveness | Use MediaQuery to get current height of page
Now left hand section can individually scroll, and on click of any option from this section you can define behaviour for right section; while keeping the left section constant throughout page lifecycle
I am new to flutter, and I having trouble with my ListView. My ListView contains many items, the item of ListView includes question content and some comments of users.
The item height is automatically decided by its children height, also the first children of the item (deepOrange Container below) height is dependent to parent item height (is't the item of ListView), its height must be fill to parent item.
The items size of ListView dependent to its children items size,
also the first widget (Container below) in the item is dependent to parent item too.
How i can do this?
I'm very very sorry, English is not my primate language, my English is very poor. Here is my code:
import 'package:flutter/material.dart';
import 'package:flutter/scheduler.dart';
class MainPage extends StatefulWidget {
const MainPage({Key key, this.title}) : super(key: key);
final String title;
#override
_MainPageState createState() => _MainPageState();
}
class _MainPageState extends State<MainPage> {
var items = List.generate(10, (index) => index);
#override
Widget build(BuildContext context) {
return Scaffold(
body: ListView(
children: items.map((item) => Row(
/*I can't compute the real rendered height of the item by it's children content, because it's possible contain many replay message, different font size etc.*/
children: <Widget>[
Container(
width: 5.0,
/**
* I want to fill the height to parent widget of the container,
* (I want to make an timeline widget, it's should max height to its parent.)
* but i can't get parent items size, or double.infinity etc,
*/
height: 80.0, // How to fill the height to parent of the property? or how to get parent item size (or actually rendered height)?
color: Colors.deepOrange,
),
SizedBox(width: 10.0,),
Expanded(
child: Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
Text("there is long comment of users, there is long comment of users, there is long comment of users, there is long comment of users, there is long comment of users, $item"),
/*
Also here is a lists of replay message by another user.
* */
Column(children: <Widget>[
Text("replay 1"),
Text("replay 2"),
Text("replay 3"),
Text("replay N"),
],),
Row(
children: <Widget>[
IconButton(icon: Icon(Icons.favorite)),
IconButton(icon: Icon(Icons.delete)),
IconButton(icon: Icon(Icons.message)),
],
)
],
),
),
],
),).toList(),
),
);
}
}
I simply want to fit that purple Container's height to the parent container.
Thank you in advance.
Wrap your list in a container. Then set the height to the screen size. You can get that through the MediaQuery.
var screenSize = MediaQuery.of(context).size;
Container(
height: screenSize.height,
width: screenSize.width,
child: ListView(...));
Is there a simple (non-LayoutBuilder) way to size an element relative to screen size (width/height)? For example: how do I set the width of a CardView to be 65% of the screen width.
It can't be done inside the build method (obviously) so it would have to be deferred until post build. Is there a preferred place to put logic like this?
This is a supplemental answer showing the implementation of a couple of the solutions mentioned.
FractionallySizedBox
If you have a single widget you can use a FractionallySizedBox widget to specify a percentage of the available space to fill. Here the green Container is set to fill 70% of the available width and 30% of the available height.
Widget myWidget() {
return FractionallySizedBox(
widthFactor: 0.7,
heightFactor: 0.3,
child: Container(
color: Colors.green,
),
);
}
Expanded
The Expanded widget allows a widget to fill the available space, horizontally if it is in a row, or vertically if it is in a column. You can use the flex property with multiple widgets to give them weights. Here the green Container takes 70% of the width and the yellow Container takes 30% of the width.
If you want to do it vertically, then just replace Row with Column.
Widget myWidget() {
return Row(
children: <Widget>[
Expanded(
flex: 7,
child: Container(
color: Colors.green,
),
),
Expanded(
flex: 3,
child: Container(
color: Colors.yellow,
),
),
],
);
}
Supplemental code
Here is the main.dart code for your reference.
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
appBar: AppBar(
title: Text("FractionallySizedBox"),
),
body: myWidget(),
),
);
}
}
// replace with example code above
Widget myWidget() {
return ...
}
FractionallySizedBox may also be useful.
You can also read the screen width directly out of MediaQuery.of(context).size and create a sized box based on that
MediaQuery.of(context).size.width * 0.65
if you really want to size as a fraction of the screen regardless of what the layout is.
This might be a little more clear:
double width = MediaQuery.of(context).size.width;
double yourWidth = width * 0.65;
Hope this solved your problem.
There are several possibilities:
1- The first one is the use of the MediaQuery :
Code :
MediaQuery.of(context).size.width //to get the width of screen
MediaQuery.of(context).size.height //to get height of screen
Example of use :
Container(
color: Colors.yellow,
height: MediaQuery.of(context).size.height * 0.65,
width: MediaQuery.of(context).size.width,
)
Output :
2- The use of FractionallySizedBox
Creates a widget that sizes its child to a fraction of the total available space.
Example :
FractionallySizedBox(
widthFactor: 0.65, // between 0 and 1
heightFactor: 1.0,
child:Container(color: Colors.red
,),
)
Output :
3- The use of other widgets such as Expanded , Flexible and AspectRatio and more .
You could build a Column/Row with Flexible or Expanded children that have flex values that add up to the percentages you want.
You may also find the AspectRatio widget useful.
There is many way to do this.
1. Using MediaQuery : Its return fullscreen of your device including appbar,toolbar
Container(
width: MediaQuery.of(context).size.width * 0.50,
height: MediaQuery.of(context).size.height*0.50,
color: Colors.blueAccent[400],
)
2. Using Expanded : You can set width/height in ratio
Container(
height: MediaQuery.of(context).size.height * 0.50,
child: Row(
children: <Widget>[
Expanded(
flex: 70,
child: Container(
color: Colors.lightBlue[400],
),
),
Expanded(
flex: 30,
child: Container(
color: Colors.deepPurple[800],
),
)
],
),
)
3. Others Like Flexible and AspectRatio and FractionallySizedBox
First get the size of screen.
Size size = MediaQuery.of(context).size;
After this you can get width and multiply it with 0.5 to get 50% of screen width.
double width50 = size.width * 0.5;
But problem generally comes in height, by default when we use
double screenHeight = size.height;
The height we get is global height which includes StatusBar + notch + AppBar height. So, in order to get the left height of the device, we need to subtract padding height (StatusBar + notch) and AppBar height from total height. Here is how we do it.
double abovePadding = MediaQuery.of(context).padding.top;
double appBarHeight = appBar.preferredSize.height;
double leftHeight = screenHeight - abovePadding - appBarHeight;
Now we can use following to get 50% of our screen in height.
double height50 = leftHeight * 0.5
MediaQuery.of(context).size.width
you can use MediaQuery with the current context of your widget and get width or height like this
double width = MediaQuery.of(context).size.width
double height = MediaQuery.of(context).size.height
after that, you can multiply it with the percentage you want
Use the LayoutBuilder Widget that will give you constraints that you can use to obtain the height that excludes the AppBar and the padding. Then use a SizedBox and provide the width and height using the constraints from the LayoutBuilder
return LayoutBuilder(builder: (context2, constraints) {
return Column(
children: <Widget>[
SizedBox(
width: constraints.maxWidth,
height: constraints.maxHeight,
...
if you are using GridView you can use something like Ian Hickson's solution.
crossAxisCount: MediaQuery.of(context).size.width <= 400.0 ? 3 : MediaQuery.of(context).size.width >= 1000.0 ? 5 : 4
Code :
MediaQuery.of(context).size.width //to get the width of screen
MediaQuery.of(context).size.height //to get height of screen
You can use the Align widget. The heightFactor and widthFactor parameters are multiplied by the size of the child widget. Here is an example that will make a widget with a fixed height in% ratio
Align(
alignment: Alignment.topCenter,
heightFactor: 0.63,
widthFactor: ,
child: Container(
width: double.infinity,
),
Use scaler to define the layout width and height in percentage
dependencies:
scaler: ^1.1.0+1
After setting this in pubspec.yaml you can use this by following the code -
import 'package:scaler/scaler.dart';
Example After import use this -
import 'package:scaler/scaler.dart';
#override
Widget build(BuildContext context) {
/**
* Container with 25% width of screen
* and 25% height of screen
*/
return Container(
height: Scaler.height(0.25, context),
width: Scaler.width(0.25, context),
child: Container()
);
}
To more detail about this
https://pub.dev/packages/scaler
For width
double width = MediaQuery.of(context).size.width;
double yourWidth = width * 0.75;
For Height
double height = MediaQuery.of(context).size.height;
double yourHeight = height * 0.75;
If you don't want static height and width just use Expanded widget\
import 'package:flutter/material.dart';
void main() => runApp(const MyApp());
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
static const String _title = 'Flutter Code Sample';
#override
Widget build(BuildContext context) {
return const MaterialApp(
title: _title,
home: MyStatelessWidget(),
);
}
}
class MyStatelessWidget extends StatelessWidget {
const MyStatelessWidget({Key? key}) : super(key: key);
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('Expanded Row Sample'),
),
body: Center(
child: Row(
children: <Widget>[
Expanded(
flex: 2,
child: Container(
color: Colors.amber,
height: 100,
),
),
Container(
color: Colors.blue,
height: 100,
width: 50,
),
Expanded(
child: Container(
color: Colors.amber,
height: 100,
),
),
],
),
),
);
}
}
I am surprised that no one has yet suggested LayoutBuilder in 2023 which gives you access to the parent's width BoxConstraints.constraints.maxWidth, which is the most versatile method.
Expanded can only set the percentage of the available spacing, but what if you really want to set a percentage based on the actual parent's widget only, not the entire screen width, what if have a fixed width widget in a row, even a more complex, what if you also want an Expanded to expand the remaining Row.
MediaQuery.of(context).size.width is relative to the entire screen, not to the actual parent.
FractionallySizedBox works similarly but you can't put it in Row
Also, this method the perfect emulation of CSS % unit of measurement.
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
#override
Widget build(BuildContext context) {
return LayoutBuilder(
builder: (context, BoxConstraints constraints) {
return SizedBox(
width: 470,
child: Row(
children: [
SizedBox(
width: 200,
child: Icon(
Icons.link,
color: Colors.white,
),
),
SizedBox(
width: constraints.maxWidth*0.6,
child: Icon(
Icons.message,
color: Colors.white,
),
),
Expanded(
child: Icon(
Icons.phone,
color: Colors.white,
),
),
SizedBox(
width: constraints.maxWidth*0.3,
child: Icon(
Icons.account_balance,
color: Colors.white,
),
),
],
),
);
}
);
}
}
In this example, we are setting a parent widget of 470 width with Row inside. In the Row, one element has a 200 fixed width, another with a 60% of the parent with 470, another with 30% of that same parent, and another expanding any remaining space.