Quick and dirty null-safety

.gitignore

@@ -29,6 +29,8 @@
 .pub-cache/
 .pub/
 /build/
+pubspec.lock
+example/pubspec.lock
 
 # Web related
 lib/generated_plugin_registrant.dart

example/lib/screens.dart

@@ -7,11 +7,8 @@ class MainScreen extends StatelessWidget {
   final BuildContext menuScreenContext;
   final Function onScreenHideButtonPressed;
   final bool hideStatus;
-  const MainScreen(
-      {Key key,
-      this.menuScreenContext,
-      this.onScreenHideButtonPressed,
-      this.hideStatus = false})
+
+  const MainScreen({Key key, this.menuScreenContext, this.onScreenHideButtonPressed, this.hideStatus = false})
       : super(key: key);
 
   @override
@@ -27,8 +24,7 @@ class MainScreen extends StatelessWidget {
             crossAxisAlignment: CrossAxisAlignment.center,
             children: <Widget>[
               Padding(
-                padding: const EdgeInsets.symmetric(
-                    horizontal: 30.0, vertical: 20.0),
+                padding: const EdgeInsets.symmetric(horizontal: 30.0, vertical: 20.0),
                 child: TextField(
                   decoration: InputDecoration(hintText: "Test Text Field"),
                 ),
@@ -41,8 +37,7 @@ class MainScreen extends StatelessWidget {
                       context,
                       settings: RouteSettings(name: '/home'),
                       screen: MainScreen2(),
-                      pageTransitionAnimation:
-                          PageTransitionAnimation.scaleRotate,
+                      pageTransitionAnimation: PageTransitionAnimation.scaleRotate,
                     );
                   },
                   child: Text(
@@ -88,11 +83,11 @@ class MainScreen extends StatelessWidget {
                       backgroundColor: Colors.white,
                       useRootNavigator: false,
                       builder: (context) => Center(
-                        child: RaisedButton(
+                        child: ElevatedButton(
+                          style: ElevatedButton.styleFrom(primary: Colors.blue),
                           onPressed: () {
                             Navigator.pop(context);
                           },
-                          color: Colors.blue,
                           child: Text(
                             "Exit",
                             style: TextStyle(color: Colors.white),
@@ -111,8 +106,7 @@ class MainScreen extends StatelessWidget {
                 child: RaisedButton(
                   color: Colors.lime,
                   onPressed: () {
-                    pushDynamicScreen(context,
-                        screen: SampleModalScreen(), withNavBar: true);
+                    pushDynamicScreen(context, screen: SampleModalScreen(), withNavBar: true);
                   },
                   child: Text(
                     "Push Dynamic/Modal Screen",
@@ -127,9 +121,7 @@ class MainScreen extends StatelessWidget {
                     this.onScreenHideButtonPressed();
                   },
                   child: Text(
-                    this.hideStatus
-                        ? "Unhide Navigation Bar"
-                        : "Hide Navigation Bar",
+                    this.hideStatus ? "Unhide Navigation Bar" : "Hide Navigation Bar",
                     style: TextStyle(color: Colors.white),
                   ),
                 ),

lib/animations/animations.dart

@@ -2,28 +2,28 @@ part of persistent_bottom_nav_bar;
 
 class OffsetAnimation extends StatefulWidget {
   OffsetAnimation(
-      {Key key,
+      {Key? key,
       this.child,
       this.hideNavigationBar,
       this.navBarHeight,
       this.onAnimationComplete,
       this.extendedLength = false})
       : super(key: key);
-  final Widget child;
-  final bool hideNavigationBar;
-  final double navBarHeight;
+  final Widget? child;
+  final bool? hideNavigationBar;
+  final double? navBarHeight;
   final bool extendedLength;
-  final Function(bool, bool) onAnimationComplete;
+  final Function(bool, bool)? onAnimationComplete;
 
   @override
   _OffsetAnimationState createState() => _OffsetAnimationState();
 }
 
 class _OffsetAnimationState extends State<OffsetAnimation>
     with SingleTickerProviderStateMixin {
-  AnimationController _navBarHideAnimationController;
-  Animation<Offset> _navBarOffsetAnimation;
-  bool _hideNavigationBar;
+  late AnimationController _navBarHideAnimationController;
+  late Animation<Offset> _navBarOffsetAnimation;
+  bool? _hideNavigationBar;
 
   @override
   void initState() {
@@ -33,14 +33,14 @@ class _OffsetAnimationState extends State<OffsetAnimation>
     _navBarHideAnimationController =
         AnimationController(vsync: this, duration: Duration(milliseconds: 200));
     _navBarOffsetAnimation = Tween<Offset>(
-            begin: Offset(0, 0), end: Offset(0, widget.navBarHeight + 22.0))
+            begin: Offset(0, 0), end: Offset(0, widget.navBarHeight! + 22.0))
         .chain(CurveTween(curve: Curves.ease))
         .animate(_navBarHideAnimationController);
 
     _hideAnimation();
 
     _navBarHideAnimationController.addListener(() {
-      widget.onAnimationComplete(_navBarHideAnimationController.isAnimating,
+      widget.onAnimationComplete!(_navBarHideAnimationController.isAnimating,
           _navBarHideAnimationController.isCompleted);
     });
   }
@@ -52,8 +52,8 @@ class _OffsetAnimationState extends State<OffsetAnimation>
   }
 
   _hideAnimation() {
-    WidgetsBinding.instance.addPostFrameCallback((_) {
-      if (_hideNavigationBar) {
+    WidgetsBinding.instance!.addPostFrameCallback((_) {
+      if (_hideNavigationBar!) {
         _navBarHideAnimationController.forward();
       } else {
         _navBarHideAnimationController.reverse();

lib/models/nav-bar-animation.model.dart

@@ -13,8 +13,8 @@ class ScreenTransitionAnimation {
 }
 
 class ItemAnimationProperties {
-  final Duration duration;
-  final Curve curve;
+  final Duration? duration;
+  final Curve? curve;
 
   const ItemAnimationProperties({this.duration, this.curve});
 }

lib/models/nav-bar-essentials.model.dart

@@ -1,43 +1,43 @@
 part of persistent_bottom_nav_bar;
 
 class NavBarEssentials {
-  final int selectedIndex;
-  final int previousIndex;
-  final Color backgroundColor;
-  final List<PersistentBottomNavBarItem> items;
-  final ValueChanged<int> onItemSelected;
-  final double navBarHeight;
-  final NavBarPadding padding;
-  final Function(int) popAllScreensForTheSelectedTab;
-  final bool popScreensOnTapOfSelectedTab;
-  final ItemAnimationProperties itemAnimationProperties;
+  final int? selectedIndex;
+  final int? previousIndex;
+  final Color? backgroundColor;
+  final List<PersistentBottomNavBarItem>? items;
+  final ValueChanged<int>? onItemSelected;
+  final double? navBarHeight;
+  final NavBarPadding? padding;
+  final Function(int)? popAllScreensForTheSelectedTab;
+  final bool? popScreensOnTapOfSelectedTab;
+  final ItemAnimationProperties? itemAnimationProperties;
 
   const NavBarEssentials({
-    Key key,
+    Key? key,
     this.selectedIndex,
     this.previousIndex,
     this.backgroundColor,
     this.popScreensOnTapOfSelectedTab,
     this.itemAnimationProperties,
     this.navBarHeight = 0.0,
-    @required this.items,
+    required this.items,
     this.onItemSelected,
     this.popAllScreensForTheSelectedTab,
     this.padding,
   });
 
   NavBarEssentials copyWith({
-    int selectedIndex,
-    int previousIndex,
-    double iconSize,
-    Color backgroundColor,
-    List<PersistentBottomNavBarItem> items,
-    ValueChanged<int> onItemSelected,
-    double navBarHeight,
-    NavBarPadding padding,
-    Function(int) popAllScreensForTheSelectedTab,
-    bool popScreensOnTapOfSelectedTab,
-    ItemAnimationProperties itemAnimationProperties,
+    int? selectedIndex,
+    int? previousIndex,
+    double? iconSize,
+    Color? backgroundColor,
+    List<PersistentBottomNavBarItem>? items,
+    ValueChanged<int>? onItemSelected,
+    double? navBarHeight,
+    NavBarPadding? padding,
+    Function(int)? popAllScreensForTheSelectedTab,
+    bool? popScreensOnTapOfSelectedTab,
+    ItemAnimationProperties? itemAnimationProperties,
   }) {
     return NavBarEssentials(
       selectedIndex: selectedIndex ?? this.selectedIndex,