#539 viewer: stiffer spring physics for vertical pager

lib/theme/durations.dart

@@ -84,7 +84,7 @@ class DurationsData {
   final Duration tvImageFocusAnimation;
 
   // viewer animations
-  final Duration viewerVerticalPageScrollAnimation;
+  final Duration viewerHorizontalPageScrollAnimation;
   final Duration viewerOverlayAnimation;
   final Duration viewerOverlayChangeAnimation;
 
@@ -102,7 +102,7 @@ class DurationsData {
     this.staggeredAnimationPageTarget = const Duration(milliseconds: 800),
     this.quickChooserAnimation = const Duration(milliseconds: 100),
     this.tvImageFocusAnimation = const Duration(milliseconds: 150),
-    this.viewerVerticalPageScrollAnimation = const Duration(milliseconds: 500),
+    this.viewerHorizontalPageScrollAnimation = const Duration(milliseconds: 400),
     this.viewerOverlayAnimation = const Duration(milliseconds: 200),
     this.viewerOverlayChangeAnimation = const Duration(milliseconds: 150),
   }) : staggeredAnimationDelay = staggeredAnimation ~/ 6;
@@ -120,7 +120,7 @@ class DurationsData {
       staggeredAnimationPageTarget: Duration.zero,
       quickChooserAnimation: Duration.zero,
       tvImageFocusAnimation: Duration.zero,
-      viewerVerticalPageScrollAnimation: Duration.zero,
+      viewerHorizontalPageScrollAnimation: Duration.zero,
       viewerOverlayAnimation: Duration.zero,
       viewerOverlayChangeAnimation: Duration.zero,
     );

lib/widgets/common/behaviour/springy_scroll_physics.dart

@@ -0,0 +1,20 @@
+import 'package:flutter/widgets.dart';
+
+class SpringyScrollPhysics extends ScrollPhysics {
+  @override
+  final SpringDescription spring;
+
+  const SpringyScrollPhysics({
+    required this.spring,
+    super.parent,
+  });
+
+  @override
+  SpringyScrollPhysics applyTo(ScrollPhysics? ancestor) {
+    return SpringyScrollPhysics(
+      spring: spring,
+      parent: buildParent(ancestor),
+    );
+  }
+
+}

lib/widgets/viewer/entry_vertical_pager.dart

@@ -10,6 +10,7 @@ import 'package:aves/model/entry/extensions/props.dart';
 import 'package:aves/model/settings/settings.dart';
 import 'package:aves/model/source/collection_lens.dart';
 import 'package:aves/theme/durations.dart';
+import 'package:aves/widgets/common/behaviour/springy_scroll_physics.dart';
 import 'package:aves/widgets/viewer/action/entry_action_delegate.dart';
 import 'package:aves/widgets/viewer/controls/controller.dart';
 import 'package:aves/widgets/viewer/controls/intents.dart';
@@ -37,6 +38,13 @@ class ViewerVerticalPageView extends StatefulWidget {
   final VoidCallback onImagePageRequested;
   final void Function(AvesEntry mainEntry, AvesEntry? pageEntry) onViewDisposed;
 
+  // critically damped spring a bit stiffer than `ScrollPhysics._kDefaultSpring`
+  static final spring = SpringDescription.withDampingRatio(
+    mass: 0.5,
+    stiffness: 200.0,
+    ratio: 1.0,
+  );
+
   const ViewerVerticalPageView({
     super.key,
     required this.collection,
@@ -180,7 +188,9 @@ class _ViewerVerticalPageViewState extends State<ViewerVerticalPageView> {
         controller: widget.verticalPager,
         physics: MagnifierScrollerPhysics(
           gestureSettings: context.select<MediaQueryData, DeviceGestureSettings>((mq) => mq.gestureSettings),
-          parent: const PageScrollPhysics(),
+          parent: SpringyScrollPhysics(
+            spring: ViewerVerticalPageView.spring,
+          ),
         ),
         onPageChanged: widget.onVerticalPageChanged,
         children: pages,

lib/widgets/viewer/entry_viewer_stack.dart

@@ -9,6 +9,7 @@ import 'package:aves/model/entry/extensions/props.dart';
 import 'package:aves/model/filters/filters.dart';
 import 'package:aves/model/filters/trash.dart';
 import 'package:aves/model/highlight.dart';
+import 'package:aves/model/settings/enums/accessibility_animations.dart';
 import 'package:aves/model/settings/enums/accessibility_timeout.dart';
 import 'package:aves/model/settings/settings.dart';
 import 'package:aves/model/source/collection_lens.dart';
@@ -62,7 +63,7 @@ class EntryViewerStack extends StatefulWidget {
   State<EntryViewerStack> createState() => _EntryViewerStackState();
 }
 
-class _EntryViewerStackState extends State<EntryViewerStack> with EntryViewControllerMixin, FeedbackMixin, SingleTickerProviderStateMixin {
+class _EntryViewerStackState extends State<EntryViewerStack> with EntryViewControllerMixin, FeedbackMixin, TickerProviderStateMixin {
   final Floating _floating = Floating();
   late int _currentEntryIndex;
   late ValueNotifier<int> _currentVerticalPage;
@@ -72,7 +73,7 @@ class _EntryViewerStackState extends State<EntryViewerStack> with EntryViewContr
   final ValueNotifier<bool> _overlayVisible = ValueNotifier(true);
   final ValueNotifier<bool> _viewLocked = ValueNotifier(false);
   final ValueNotifier<bool> _overlayExpandedNotifier = ValueNotifier(false);
-  late AnimationController _overlayAnimationController;
+  late AnimationController _verticalPageAnimationController, _overlayAnimationController;
   late Animation<double> _overlayButtonScale, _overlayVideoControlScale, _overlayOpacity;
   late Animation<Offset> _overlayTopOffset;
   EdgeInsets? _frozenViewInsets, _frozenViewPadding;
@@ -125,6 +126,8 @@ class _EntryViewerStackState extends State<EntryViewerStack> with EntryViewContr
     _currentVerticalPage = ValueNotifier(imagePage);
     _horizontalPager = PageController(initialPage: _currentEntryIndex);
     _verticalPager = PageController(initialPage: _currentVerticalPage.value)..addListener(_onVerticalPageControllerChanged);
+    _verticalPageAnimationController = AnimationController.unbounded(vsync: this);
+    _verticalPageAnimationController.addListener(() => _verticalPager.jumpTo(_verticalPageAnimationController.value));
     _overlayAnimationController = AnimationController(
       duration: context.read<DurationsData>().viewerOverlayAnimation,
       vsync: this,
@@ -171,6 +174,7 @@ class _EntryViewerStackState extends State<EntryViewerStack> with EntryViewContr
     _floating.dispose();
     cleanEntryControllers(entryNotifier.value);
     _videoActionDelegate.dispose();
+    _verticalPageAnimationController.dispose();
     _overlayAnimationController.dispose();
     _overlayVisible.dispose();
     _viewLocked.dispose();
@@ -606,14 +610,11 @@ class _EntryViewerStackState extends State<EntryViewerStack> with EntryViewContr
   }
 
   Future<void> _goToVerticalPage(int page) async {
-    final animationDuration = context.read<DurationsData>().viewerVerticalPageScrollAnimation;
+    if (settings.accessibilityAnimations.animate) {
-    if (animationDuration > Duration.zero) {
+      final start = _verticalPager.offset;
-      // duration & curve should feel similar to changing page by vertical fling
+      final end = _verticalPager.position.viewportDimension * page;
-      await _verticalPager.animateToPage(
+      final simulation = ScrollSpringSimulation(ViewerVerticalPageView.spring, start, end, 0);
-        page,
+      unawaited(_verticalPageAnimationController.animateWith(simulation));
-        duration: animationDuration,
-        curve: Curves.easeOutQuart,
-      );
     } else {
       _verticalPager.jumpToPage(page);
     }
@@ -653,13 +654,13 @@ class _EntryViewerStackState extends State<EntryViewerStack> with EntryViewContr
         page = page.clamp(0, _collection.entryCount - 1);
       }
       if (_currentEntryIndex != page) {
-        final animationDuration = animate ? context.read<DurationsData>().viewerVerticalPageScrollAnimation : Duration.zero;
+        final animationDuration = animate ? context.read<DurationsData>().viewerHorizontalPageScrollAnimation : Duration.zero;
         if (animationDuration > Duration.zero) {
-          // duration & curve should feel similar to changing page by vertical fling
+          // duration & curve should feel similar to changing page by fling
           await _horizontalPager.animateToPage(
             page,
             duration: animationDuration,
-            curve: Curves.easeOutQuart,
+            curve: Curves.easeOutCubic,
           );
         } else {
           _horizontalPager.jumpToPage(page);

lib/widgets/viewer/info/info_page.dart

@@ -124,11 +124,10 @@ class _InfoPageState extends State<InfoPage> {
   }
 
   void _goToViewer() {
-    final animationDuration = context.read<DurationsData>().viewerVerticalPageScrollAnimation;
     ShowImageNotification().dispatch(context);
     _scrollController.animateTo(
       0,
-      duration: animationDuration,
+      duration: Durations.pageTransitionAnimation,
       curve: Curves.easeInOut,
     );
   }

plugins/aves_magnifier/lib/src/pan/scroll_physics.dart

@@ -17,8 +17,8 @@ class MagnifierScrollerPhysics extends ScrollPhysics {
   const MagnifierScrollerPhysics({
     required this.gestureSettings,
     this.touchSlopFactor = 1,
-    ScrollPhysics? parent,
+    super.parent,
-  }) : super(parent: parent);
+  });
 
   @override
   MagnifierScrollerPhysics applyTo(ScrollPhysics? ancestor) {