null safety

-<!--
- * @Author: zhuoyuan93@gmail.com
- * @Date: 2018-10-16 19:43:03
- * @LastEditors: zhuoyuan93@gmail.com
- * @LastEditTime: 2020年6月20日 11:20:02
- * @Description: Update log
- -->
+# 5.0.0-nullsafety.0
+- Migrated flutter_screenutil to non-nullable
 
 # 4.0.0-beta3
 - Optimize the way of initialization

@@ -16,54 +16,14 @@ dependencies:
   flutter:
     sdk: flutter
 
-  # The following adds the Cupertino Icons font to your application.
-  # Use with the CupertinoIcons class for iOS style icons.
-  cupertino_icons: ^0.1.2
   flutter_screenutil:
-    path: ../
+
 dev_dependencies:
   flutter_test:
     sdk: flutter
+  test: ^1.15.7
 
+dependency_overrides:
+  flutter_screenutil:
+    path: ../
 
-# For information on the generic Dart part of this file, see the
-# following page: https://www.dartlang.org/tools/pub/pubspec
-
-# The following section is specific to Flutter.
-flutter:
-
-  # The following line ensures that the Material Icons font is
-  # included with your application, so that you can use the icons in
-  # the material Icons class.
-  uses-material-design: true
-
-  # To add assets to your application, add an assets section, like this:
-  # assets:
-  #  - images/a_dot_burr.jpeg
-  #  - images/a_dot_ham.jpeg
-
-  # An image asset can refer to one or more resolution-specific "variants", see
-  # https://flutter.io/assets-and-images/#resolution-aware.
-
-  # For details regarding adding assets from package dependencies, see
-  # https://flutter.io/assets-and-images/#from-packages
-
-  # To add custom fonts to your application, add a fonts section here,
-  # in this "flutter" section. Each entry in this list should have a
-  # "family" key with the font family name, and a "fonts" key with a
-  # list giving the asset and other descriptors for the font. For
-  # example:
-  # fonts:
-  #   - family: Schyler
-  #     fonts:
-  #       - asset: fonts/Schyler-Regular.ttf
-  #       - asset: fonts/Schyler-Italic.ttf
-  #         style: italic
-  #   - family: Trajan Pro
-  #     fonts:
-  #       - asset: fonts/TrajanPro.ttf
-  #       - asset: fonts/TrajanPro_Bold.ttf
-  #         weight: 700
-  #
-  # For details regarding fonts from package dependencies,
-  # see https://flutter.io/custom-fonts/#from-packages

@@ -8,30 +8,26 @@ import 'dart:ui' as ui;
 
 class ScreenUtil {
   static const Size defaultSize = Size(1080, 1920);
-  static ScreenUtil _instance;
+  static late ScreenUtil _instance;
 
   /// UI设计中手机尺寸 , px
   /// Size of the phone in UI Design , px
-  Size uiSize;
+  late Size uiSize;
 
   /// 控制字体是否要根据系统的“字体大小”辅助选项来进行缩放。默认值为false。
   /// allowFontScaling Specifies whether fonts should scale to respect Text Size accessibility settings. The default is false.
-  bool allowFontScaling;
+  late bool allowFontScaling;
 
-  static double _pixelRatio;
-  static double _textScaleFactor;
-  static double _screenWidth;
-  static double _screenHeight;
-  static double _statusBarHeight;
-  static double _bottomBarHeight;
+  static late double _pixelRatio;
+  static late double _textScaleFactor;
+  static late double _screenWidth;
+  static late double _screenHeight;
+  static late double _statusBarHeight;
+  static late double _bottomBarHeight;
 
   ScreenUtil._();
 
   factory ScreenUtil() {
-    assert(
-      _instance != null,
-      '\nEnsure to initialize ScreenUtil before accessing it.\nPlease execute the init method : ScreenUtil.init()',
-    );
     return _instance;
   }
 
@@ -40,7 +36,7 @@ class ScreenUtil {
     Size designSize = defaultSize,
     bool allowFontScaling = false,
   }) {
-    _instance ??= ScreenUtil._();
+    _instance = ScreenUtil._();
     _instance
       ..uiSize = designSize
       ..allowFontScaling = allowFontScaling;
@@ -116,7 +112,7 @@ class ScreenUtil {
   ///Font size adaptation method
   ///- [fontSize] The size of the font on the UI design, in px.
   ///- [allowFontScaling]
-  double setSp(num fontSize, {bool allowFontScalingSelf}) =>
+  double setSp(num fontSize, {bool? allowFontScalingSelf}) =>
       allowFontScalingSelf == null
           ? (allowFontScaling
               ? (fontSize * scaleText)

@@ -5,10 +5,10 @@ import 'screenutil.dart';
 class ScreenUtilInit extends StatelessWidget {
   /// A helper widget that initializes [ScreenUtil]
   ScreenUtilInit({
-    @required this.child,
+    required this.child,
     this.designSize = ScreenUtil.defaultSize,
     this.allowFontScaling = false,
-    Key key,
+    Key? key,
   }) : super(key: key);
 
   final Widget child;

 name: flutter_screenutil
 description: A flutter plugin for adapting screen and font size.Guaranteed to look good on different models
-version: 4.0.0-beta3
+version: 5.0.0-nullsafety.0
 homepage: https://github.com/OpenFlutter/flutter_screenutil
 
 environment:
-  sdk: ">=2.6.0 <3.0.0"
+  sdk: '>=2.12.0-29.10.beta <3.0.0'
 
 dependencies:
   flutter: