phase3: util_web + shop_scroll (custom scroll) null-safe; global Key? param fix

lib/utils/double_back_to_close_app.dart

@@ -21,7 +21,7 @@ class DoubleBackToCloseApp extends StatefulWidget {
   /// Creates a widget that allows the user to close the app by double tapping
   /// the back-button.
   const DoubleBackToCloseApp({
-    Key key,
+    Key? key,
     @required this.snackBar,
     @required this.child,
   })  : assert(snackBar != null),

lib/utils/shop_scroll_controller.dart

@@ -38,7 +38,7 @@ class ShopScrollController extends ScrollController {
   final bool keepScrollOffset;
 
   /// [toString]输出中使用的标签。 旨在帮助在调试输出中标识滚动控制器实例。
-  final String debugLabel;
+  final String? debugLabel;
 
   /// The currently attached positions. 当前附加的 [positions]。
   /// 这不应直接突变。 可以使用[attach]和[detach]添加和删除[ScrollPosition]对象。
@@ -61,7 +61,7 @@ class ShopScrollController extends ScrollController {
         'ScrollController not attached to any scroll views.');
     assert(_positions.length == 1,
         'ScrollController attached to multiple scroll views.');
-    return _positions.single;
+    return _positions.single as ShopScrollPosition;
   }
 
   /// 可滚动小部件的当前滚动偏移量
@@ -83,12 +83,12 @@ class ShopScrollController extends ScrollController {
   /// 持续时间不能为零。 要在没有动画的情况下跳至特定值，请使用[jumpTo]。
   Future<void> animateTo(
     double offset, {
-    @required Duration duration,
-    @required Curve curve,
+    required Duration duration,
+    required Curve curve,
   }) {
     assert(_positions.isNotEmpty,
         'ScrollController not attached to any scroll views.');
-    final List<Future<void>> animations = List<Future<void>>(_positions.length);
+    final List<Future<void>> animations = List<Future<void>>.filled(_positions.length, Future<void>.value());
     for (int i = 0; i < _positions.length; i += 1)
       animations[i] =
           _positions[i].animateTo(offset, duration: duration, curve: curve);
@@ -149,7 +149,7 @@ class ShopScrollController extends ScrollController {
   ///     则它将是前一个实例。 当环境已更改并且[Scrollable]需要重新创建[ScrollPosition]
   ///     对象时，将使用此方法。 第一次创建[ScrollPosition]时为null。
   ScrollPosition createScrollPosition(ScrollPhysics physics,
-      ScrollContext context, ScrollPosition oldPosition) {
+      ScrollContext context, ScrollPosition? oldPosition) {
     return ShopScrollPosition(
       coordinator: coordinator,
       physics: physics,
@@ -175,7 +175,7 @@ class ShopScrollController extends ScrollController {
   @mustCallSuper
   void debugFillDescription(List<String> description) {
     super.debugFillDescription(description);
-    if (debugLabel != null) description.add(debugLabel);
+    if (debugLabel != null) description.add(debugLabel!);
     if (initialScrollOffset != 0.0)
       description.add(
           'initialScrollOffset: ${initialScrollOffset.toStringAsFixed(1)}, ');

lib/utils/shop_scroll_coordinator.dart

@@ -12,15 +12,15 @@ class ShopScrollCoordinator {
   /// 页面主 CustomScrollView 控制
   final String pageLabel = "page";
 
-  ShopScrollController _pageScrollController;
-  double Function() pinnedHeaderSliverHeightBuilder;
+  late ShopScrollController _pageScrollController;
+  double Function()? pinnedHeaderSliverHeightBuilder;
 
   ShopScrollPosition get _pageScrollPosition => _pageScrollController.position;
 
-  ScrollDragController scrollDragController;
+  late ScrollDragController scrollDragController;
 
   /// 主页面滑动部件默认位置
-  double _pageInitialOffset;
+  late double _pageInitialOffset;
 
   /// 获取主页面滑动控制器
   ShopScrollController pageScrollController([double initialOffset = 0.0]) {
@@ -32,26 +32,26 @@ class ShopScrollCoordinator {
   }
 
   /// 创建并获取一个子滑动控制器
-  ShopScrollController newChildScrollController([String debugLabel]) =>
+  ShopScrollController newChildScrollController([String? debugLabel]) =>
       ShopScrollController(this, debugLabel: debugLabel);
 
   /// 子部件滑动数据协调
   /// [userScrollDirection]用户滑动方向
   /// [position]被滑动的子部件的位置信息
   void applyUserOffset(double delta,
-      [ScrollDirection userScrollDirection, ShopScrollPosition position]) {
+      [ScrollDirection? userScrollDirection, ShopScrollPosition? position]) {
     if (userScrollDirection == ScrollDirection.reverse) {
-      updateUserScrollDirection(_pageScrollPosition, userScrollDirection);
+      updateUserScrollDirection(_pageScrollPosition, userScrollDirection!);
       final innerDelta = _pageScrollPosition.applyClampedDragUpdate(delta);
       if (innerDelta != 0.0) {
-        updateUserScrollDirection(position, userScrollDirection);
+        updateUserScrollDirection(position!, userScrollDirection);
         position.applyFullDragUpdate(innerDelta);
       }
     } else {
-      updateUserScrollDirection(position, userScrollDirection);
+      updateUserScrollDirection(position!, userScrollDirection!);
       final outerDelta = position.applyClampedDragUpdate(delta);
       if (outerDelta != 0.0) {
-        updateUserScrollDirection(_pageScrollPosition, userScrollDirection);
+        updateUserScrollDirection(_pageScrollPosition, userScrollDirection!);
         _pageScrollPosition.applyFullDragUpdate(outerDelta);
       }
     }
@@ -60,7 +60,7 @@ class ShopScrollCoordinator {
   bool applyContentDimensions(double minScrollExtent, double maxScrollExtent,
       ShopScrollPosition position) {
     if (pinnedHeaderSliverHeightBuilder != null) {
-      maxScrollExtent = maxScrollExtent - pinnedHeaderSliverHeightBuilder();
+      maxScrollExtent = maxScrollExtent - pinnedHeaderSliverHeightBuilder!();
       maxScrollExtent = math.max(0.0, maxScrollExtent);
     }
     return position.applyContentDimensions(

lib/utils/shop_scroll_position.dart

@@ -11,17 +11,17 @@ import 'shop_scroll_coordinator.dart';
 class ShopScrollPosition extends ScrollPosition
     implements ScrollActivityDelegate {
   final ShopScrollCoordinator coordinator; // 协调器
-  ScrollDragController _currentDrag;
+  ScrollDragController? _currentDrag;
   double _heldPreviousVelocity = 0.0;
 
   ShopScrollPosition(
-      {@required ScrollPhysics physics,
-      @required ScrollContext context,
+      {required ScrollPhysics physics,
+      required ScrollContext context,
       double initialPixels = 0.0,
       bool keepScrollOffset = true,
-      ScrollPosition oldPosition,
-      String debugLabel,
-      @required this.coordinator})
+      ScrollPosition? oldPosition,
+      String? debugLabel,
+      required this.coordinator})
       : super(
           physics: physics,
           context: context,
@@ -40,7 +40,7 @@ class ShopScrollPosition extends ScrollPosition
 
   @override
   double setPixels(double newPixels) {
-    assert(activity.isScrolling);
+    assert(activity!.isScrolling);
     return super.setPixels(newPixels);
   }
 
@@ -51,13 +51,13 @@ class ShopScrollPosition extends ScrollPosition
       goIdle();
       return;
     }
-    activity.updateDelegate(this);
+    activity!.updateDelegate(this);
     final ShopScrollPosition typedOther = other as ShopScrollPosition;
     _userScrollDirection = typedOther._userScrollDirection;
     assert(_currentDrag == null);
     if (typedOther._currentDrag != null) {
       _currentDrag = typedOther._currentDrag;
-      _currentDrag.updateDelegate(this);
+      _currentDrag!.updateDelegate(this);
       typedOther._currentDrag = null;
     }
   }
@@ -131,14 +131,14 @@ class ShopScrollPosition extends ScrollPosition
   }
 
   @override
-  void beginActivity(ScrollActivity newActivity) {
+  void beginActivity(ScrollActivity? newActivity) {
     _heldPreviousVelocity = 0.0;
     if (newActivity == null) return;
     assert(newActivity.delegate == this);
     super.beginActivity(newActivity);
     _currentDrag?.dispose();
     _currentDrag = null;
-    if (!activity.isScrolling) updateUserScrollDirection(ScrollDirection.idle);
+    if (!activity!.isScrolling) updateUserScrollDirection(ScrollDirection.idle);
   }
 
   /// 将[用户滚动方向]设置为给定值。
@@ -154,7 +154,7 @@ class ShopScrollPosition extends ScrollPosition
 
   @override
   ScrollHoldController hold(VoidCallback holdCancelCallback) {
-    final double previousVelocity = activity.velocity;
+    final double previousVelocity = activity!.velocity;
     final HoldScrollActivity holdActivity =
         HoldScrollActivity(delegate: this, onHoldCanceled: holdCancelCallback);
     beginActivity(holdActivity);
@@ -195,10 +195,10 @@ class ShopScrollPosition extends ScrollPosition
       if (coordinator.pageExpand == PageExpandState.Expanding) return;
     }
     assert(pixels != null);
-    final Simulation simulation =
+    final Simulation? simulation =
         physics.createBallisticSimulation(this, velocity);
     if (simulation != null) {
-      beginActivity(BallisticScrollActivity(this, simulation, context.vsync));
+      beginActivity(BallisticScrollActivity(this, simulation, context.vsync, false));
     } else {
       goIdle();
     }
@@ -220,8 +220,8 @@ class ShopScrollPosition extends ScrollPosition
   @override
   Future<void> animateTo(
     double to, {
-    @required Duration duration,
-    @required Curve curve,
+    required Duration duration,
+    required Curve curve,
   }) {
     if (nearEqual(to, pixels, physics.tolerance.distance)) {
       // 跳过动画，直接移到我们已经靠近的位置。