flutter_screenutil

A flutter plugin for adapting screen and font size.Let your UI display a reasonable layout on different screen sizes!

Note: This plugin is still under development, and some APIs might not be available yet.

Usage

Add dependency

Please check the latest version before installation. If there is any problem with the new version, please use the previous version

dependencies:
  flutter:
    sdk: flutter
  # add flutter_screenutil
  flutter_screenutil: ^{latest version}

Add the following imports to your Dart code

import 'package:flutter_screenutil/flutter_screenutil.dart';

Properties

Property	Type	Default Value	Description
designSize	Size	Size(360,690)	The size of the device screen in the design draft, in dp
builder	Function	null	Return widget that uses the library in a property (ex: MaterialApp's theme)
child	Widget	null	A part of builder that its dependencies/properties don't use the library
rebuildFactor	Function	default	Function that take old and new screen metrics and returns whether to rebuild or not when changes.
splitScreenMode	bool	false	support for split screen
minTextAdapt	bool	false	Whether to adapt the text according to the minimum of width and height
context	BuildContext	null	Get physical device data if not provided, by MediaQuery.of(context)
fontSizeResolver	Function	default	Function that specify how font size should be adapted. Default is that font size scale with width of screen.
responsiveWidgets	Iterable	null	List/Set of widget names that should be included in rebuilding tree. (See How flutter_screenutil marks a widget needs build)
excludeWidgets	Iterable	null	List/Set of widget names that should be excluded from rebuilding tree.
enableScaleWH	Function	null	Support enable scale width and height.
enableScaleText	Function	null	Support enable scale text.

Note : You must either provide builder, child or both.

Rebuild list

Starting from version 5.9.0, ScreenUtilInit won't rebuild the whole widget tree, instead it will mark widget needs build only if:

Widget is not a flutter widget (widgets are available in Flutter Docs)
Widget does not start with underscore (_)
Widget does not declare SU mixin
responsiveWidgets does not contains widget name

If you have a widget that uses the library and doesn't meet these options you can either add SU mixin or add widget name in responsiveWidgets list.

Initialize and set the fit size and font size to scale according to the system's "font size" accessibility option

Please set the size of the design draft before use, the width and height of the design draft.

The first way (You should use it once in your app)

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    //Set the fit size (Find your UI design, look at the dimensions of the device screen and fill it in,unit in dp)
    return ScreenUtilInit(
      designSize: const Size(360, 690),
      minTextAdapt: true,
      splitScreenMode: true,
      // Use builder only if you need to use library outside ScreenUtilInit context
      builder: (_ , child) {
        return MaterialApp(
          debugShowCheckedModeBanner: false,
          title: 'First Method',
          // You can use the library anywhere in the app even in theme
          theme: ThemeData(
            primarySwatch: Colors.blue,
            textTheme: Typography.englishLike2018.apply(fontSizeFactor: 1.sp),
          ),
          home: child,
        );
      },
      child: const HomePage(title: 'First Method'),
    );
  }
}

The second way:You need a trick to support font adaptation in the textTheme of app theme

Hybrid development uses the second way

not support this:

MaterialApp(
  ...
  //To support the following, you need to use the first initialization method
  theme: ThemeData(
    textTheme: TextTheme(
      button: TextStyle(fontSize: 45.sp)
    ),
  ),
)

but you can do this:

void main() async {
  // Add this line
  await ScreenUtil.ensureScreenSize();
  runApp(MyApp());
}
...
MaterialApp(
  ...
  builder: (ctx, child) {
    ScreenUtil.init(ctx);
    return Theme(
      data: ThemeData(
        primarySwatch: Colors.blue,
        textTheme: TextTheme(bodyText2: TextStyle(fontSize: 30.sp)),
      ),
      child: HomePage(title: 'FlutterScreenUtil Demo'),
    );
  },
)

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'Flutter_ScreenUtil',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: HomePage(title: 'FlutterScreenUtil Demo'),
    );
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    //Set the fit size (fill in the screen size of the device in the design) 
    //If the design is based on the size of the 360*690(dp)
    ScreenUtil.init(context, designSize: const Size(360, 690));
    ...
  }
}

Note: calling ScreenUtil.init second time, any non-provided parameter will not be replaced with default value. Use ScreenUtil.configure instead

API

Enable or disable scale

  Widget build(BuildContext context) {
    return ScreenUtilInit(
      enableScaleWH: ()=>false,
      enableScaleText: ()=>false,
      //...
    );
  }

ScreenUtil.enableScale(enableWH: () => false, enableText: () => false);

Pass the dp size of the design draft

    ScreenUtil().setWidth(540)  (dart sdk>=2.6 : 540.w) //Adapted to screen width
    ScreenUtil().setHeight(200) (dart sdk>=2.6 : 200.h) //Adapted to screen height , under normal circumstances, the height still uses x.w
    ScreenUtil().radius(200)    (dart sdk>=2.6 : 200.r)    //Adapt according to the smaller of width or height
    ScreenUtil().setSp(24)      (dart sdk>=2.6 : 24.sp) //Adapter font
    12.sm   //return min(12,12.sp)

    ScreenUtil().pixelRatio       //Device pixel density
    ScreenUtil().screenWidth   (dart sdk>=2.6 : 1.sw)    //Device width
    ScreenUtil().screenHeight  (dart sdk>=2.6 : 1.sh)    //Device height
    ScreenUtil().bottomBarHeight  //Bottom safe zone distance, suitable for buttons with full screen
    ScreenUtil().statusBarHeight  //Status bar height , Notch will be higher
    ScreenUtil().textScaleFactor  //System font scaling factor

    ScreenUtil().scaleWidth //The ratio of actual width to UI design
    ScreenUtil().scaleHeight //The ratio of actual height to UI design

    ScreenUtil().orientation  //Screen orientation
    0.2.sw  //0.2 times the screen width
    0.5.sh  //50% of screen height
    20.setVerticalSpacing  // SizedBox(height: 20 * scaleHeight)
    20.horizontalSpace  // SizedBox(height: 20 * scaleWidth)
    const RPadding.all(8)   // Padding.all(8.r) - take advantage of const key word
    EdgeInsets.all(10).w    //EdgeInsets.all(10.w)
    REdgeInsets.all(8)       // EdgeInsets.all(8.r)
    EdgeInsets.only(left:8,right:8).r // EdgeInsets.only(left:8.r,right:8.r).
    BoxConstraints(maxWidth: 100, minHeight: 100).w    //BoxConstraints(maxWidth: 100.w, minHeight: 100.w)
    Radius.circular(16).w          //Radius.circular(16.w)
    BorderRadius.all(Radius.circular(16)).w

Adapt screen size

Pass the dp size of the design draft((The unit is the same as the unit at initialization))：

Adapted to screen width: ScreenUtil().setWidth(540),

Adapted to screen height: ScreenUtil().setHeight(200), In general, the height is best to adapt to the width

If your dart sdk>=2.6, you can use extension functions:

example:

instead of :

Container(
  width: ScreenUtil().setWidth(50),
  height:ScreenUtil().setHeight(200),
)

you can use it like this:

Container(
  width: 50.w,
  height:200.h
)

`Note`

The height can also use setWidth to ensure that it is not deformed(when you want a square)

The setHeight method is mainly to adapt to the height, which is used when you want to control the height of a screen on the UI to be the same as the actual display.

Generally speaking, 50.w!=50.h.

//for example:

//If you want to display a rectangle:
Container(
  width: 375.w,
  height: 375.h,
),
            
//If you want to display a square based on width:
Container(
  width: 300.w,
  height: 300.w,
),

//If you want to display a square based on height:
Container(
  width: 300.h,
  height: 300.h,
),

//If you want to display a square based on minimum(height, width):
Container(
  width: 300.r,
  height: 300.r,
),

Adapter font

//Incoming font size(The unit is the same as the unit at initialization)
ScreenUtil().setSp(28) 
28.sp

//for example:
Column(
  crossAxisAlignment: CrossAxisAlignment.start,
  children: <Widget>[
    Text(
      '16sp, will not change with the system.',
      style: TextStyle(
        color: Colors.black,
        fontSize: 16.sp,
      ),
      textScaleFactor: 1.0,
    ),
    Text(
      '16sp,if data is not set in MediaQuery,my font size will change with the system.',
      style: TextStyle(
        color: Colors.black,
        fontSize: 16.sp,
      ),
    ),
  ],
)

Setting font does not change with system font size

APP global:

MaterialApp(
  debugShowCheckedModeBanner: false,
  title: 'Flutter_ScreenUtil',
  theme: ThemeData(
    primarySwatch: Colors.blue,
  ),
  builder: (context, widget) {
    return MediaQuery(
      ///Setting font does not change with system font size
      data: MediaQuery.of(context).copyWith(textScaleFactor: 1.0),
      child: widget,
    );
  },
  home: HomePage(title: 'FlutterScreenUtil Demo'),
),

Specified Text:

Text("text", textScaleFactor: 1.0)

Specified Widget:

MediaQuery(
  // If there is no context available you can wrap [MediaQuery] with [Builder]
  data: MediaQuery.of(context).copyWith(textScaleFactor: 1.0),
  child: AnyWidget(),
)

widget test

Example

example demo

To use second method run: flutter run --dart-define=method=2

Effect

Update for Version 5.9.0 (Tests)

Reported as bug in #515

In version 5.9.0, to ensure compatibility and proper functioning of your tests, it is crucial to use the method tester.pumpAndSettle(); when conducting widget tests that depend on animations or a settling time to complete their state.

In the previous version, this step was not strictly necessary. However, to maintain consistency in your tests and avoid unexpected errors, it's strongly recommended incorporating await tester.pumpAndSettle(); in your widget tests if you are using version 5.9.0

Example usage:

testWidgets('Should ensure widgets settle correctly', (WidgetTester tester) async {
await tester.pumpWidget(
  const MaterialApp(
    home: ScreenUtilInit(
      child: MyApp(),
    ),  
  ),
);
// Insertion of recommended method to prevent failures
await tester.pumpAndSettle();
// Continue with your assertions and tests
});

OpenFlutter/flutter_screenutil