flutter_screenutil

If you need to support font adaptation within the textTheme of an app theme (common in hybrid development), use the second initialization method:

1. Call await ScreenUtil.ensureScreenSize(); in your main() function.
2. Use ScreenUtil.init(context) inside the builder of your MaterialApp.

void main() async {
  // Add this line
  await ScreenUtil.ensureScreenSize();
  runApp(MyApp());
}

// Inside MaterialApp builder
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'),
  );
}

By default, .sp scales with the system's font size accessibility settings. To prevent this and keep font sizes constant, you can either set textScaleFactor: 1.0 on a specific Text widget or wrap a widget tree in a MediaQuery that overrides the textScaleFactor.

// Option 1: For a single Text widget
Text("text", textScaleFactor: 1.0)

// Option 2: For a specific widget subtree
MediaQuery(
  data: MediaQuery.of(context).copyWith(textScaleFactor: 1.0),
  child: AnyWidget(),
)

// Option 3: Globally in MaterialApp builder
MaterialApp(
  builder: (context, widget) {
    return MediaQuery(
      data: MediaQuery.of(context).copyWith(textScaleFactor: 1.0),
      child: widget,
    );
  },
  home: HomePage(),
)

For hybrid development or specific use cases where ScreenUtilInit is not used, you can manually initialize the library using ScreenUtil.init. This is typically done within a build method or a StatefulWidget's initState using BoxConstraints from a LayoutBuilder or MediaQuery.

@override
Widget build(BuildContext context) {
  ScreenUtil.init(
      BoxConstraints(
          maxWidth: MediaQuery.of(context).size.width,
          maxHeight: MediaQuery.of(context).size.height),
      designSize: Size(360, 690),
      context: context,
      orientation: Orientation.portrait);
  return Scaffold();
}

To customize the iOS launch screen, you can either replace the image files directly in the example/ios/Runner/Assets.xcassets/LaunchImage.imageset/ directory or use Xcode for a visual approach:

1. Open the iOS project in Xcode using the command: open ios/Runner.xcworkspace.
2. In the Project Navigator, select Runner/Assets.xcassets.
3. Drag and drop your desired images into the asset catalog.

If you cannot use ScreenUtilInit (e.g., in hybrid development or when you need to support text adaptation in themes manually), you can initialize it using ScreenUtil.ensureScreenSize() in main and calling ScreenUtil.init(context, designSize: ...) within a builder or a build method.

void main() async {
  await ScreenUtil.ensureScreenSize();
  runApp(MyApp());
}

// Inside MaterialApp builder or a Widget's build method:
ScreenUtil.init(context, designSize: const Size(360, 690));

Add flutter_screenutil to your pubspec.yaml dependencies. Check for the latest version before installing.

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

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

To use ScreenUtil for adaptive sizing, you must initialize it with your UI design dimensions. You can use ScreenUtil.init within a widget tree or ScreenUtil.ensureScreenSizeAndInit to wait for the window size to be available (recommended for splash screens or bootstrap logic).

Common parameters:

• designSize: The size of the phone in your UI design (default is Size(360, 690)).
• splitScreenMode: Whether to handle split-screen mode.
• minTextAdapt: Whether to adapt text based on the smaller scale factor.
• fontSizeResolver: A custom function to resolve font sizes.

When writing widget tests that depend on flutter_screenutil, you must use tester.pumpAndSettle() to ensure animations and state changes settle correctly and to avoid unexpected errors.

testWidgets('Should ensure widgets settle correctly', (WidgetTester tester) async {
  await tester.pumpWidget(
    const MaterialApp(
      home: ScreenUtilInit(
        child: MyApp(),
      ),  
    ),
  );
  await tester.pumpAndSettle();
  // Continue with assertions
});