nav bar: auto hide/show when fast scrolling

lib/widgets/collection/collection_page.dart

@@ -11,6 +11,7 @@ import 'package:aves/model/source/collection_lens.dart';
 import 'package:aves/model/source/collection_source.dart';
 import 'package:aves/theme/durations.dart';
 import 'package:aves/widgets/collection/collection_grid.dart';
+import 'package:aves/widgets/common/basic/draggable_scrollbar.dart';
 import 'package:aves/widgets/common/basic/insets.dart';
 import 'package:aves/widgets/common/behaviour/double_back_pop.dart';
 import 'package:aves/widgets/common/providers/media_query_data_provider.dart';
@@ -44,6 +45,7 @@ class CollectionPage extends StatefulWidget {
 class _CollectionPageState extends State<CollectionPage> {
   final List<StreamSubscription> _subscriptions = [];
   late CollectionLens _collection;
+  final StreamController<DraggableScrollBarEvent> _draggableScrollBarEventStreamController = StreamController.broadcast();
 
   @override
   void initState() {
@@ -78,7 +80,12 @@ class _CollectionPageState extends State<CollectionPage> {
       child: Selector<Settings, bool>(
         selector: (context, s) => s.showBottomNavigationBar,
         builder: (context, showBottomNavigationBar, child) {
-          return Scaffold(
+          return NotificationListener<DraggableScrollBarNotification>(
+            onNotification: (notification) {
+              _draggableScrollBarEventStreamController.add(notification.event);
+              return false;
+            },
+            child: Scaffold(
               body: SelectionProvider<AvesEntry>(
                 child: QueryProvider(
                   initialQuery: liveFilter?.query,
@@ -112,9 +119,15 @@ class _CollectionPageState extends State<CollectionPage> {
                 ),
               ),
               drawer: AppDrawer(currentCollection: _collection),
-            bottomNavigationBar: showBottomNavigationBar ? AppBottomNavBar(currentCollection: _collection) : null,
+              bottomNavigationBar: showBottomNavigationBar
+                  ? AppBottomNavBar(
+                      events: _draggableScrollBarEventStreamController.stream,
+                      currentCollection: _collection,
+                    )
+                  : null,
               resizeToAvoidBottomInset: false,
               extendBody: true,
+            ),
           );
         },
       ),

lib/widgets/common/basic/draggable_scrollbar.dart

@@ -303,6 +303,7 @@ class _DraggableScrollbarState extends State<DraggableScrollbar> with TickerProv
   }
 
   void _onVerticalDragStart() {
+    const DraggableScrollBarNotification(DraggableScrollBarEvent.dragStart).dispatch(context);
     _labelAnimationController.forward();
     _fadeoutTimer?.cancel();
     _showThumb();
@@ -324,6 +325,7 @@ class _DraggableScrollbarState extends State<DraggableScrollbar> with TickerProv
   }
 
   void _onVerticalDragEnd() {
+    const DraggableScrollBarNotification(DraggableScrollBarEvent.dragEnd).dispatch(context);
     _scheduleFadeout();
     setState(() => _isDragInProcess = false);
   }
@@ -454,3 +456,12 @@ class SlideFadeTransition extends StatelessWidget {
     );
   }
 }
+
+@immutable
+class DraggableScrollBarNotification extends Notification {
+  final DraggableScrollBarEvent event;
+
+  const DraggableScrollBarNotification(this.event);
+}
+
+enum DraggableScrollBarEvent { dragStart, dragEnd }

lib/widgets/filter_grids/common/filter_grid_page.dart

@@ -1,3 +1,5 @@
+import 'dart:async';
+
 import 'package:aves/app_mode.dart';
 import 'package:aves/model/filters/filters.dart';
 import 'package:aves/model/highlight.dart';
@@ -50,8 +52,9 @@ class FilterGridPage<T extends CollectionFilter> extends StatelessWidget {
   final QueryTest<T>? applyQuery;
   final Widget Function() emptyBuilder;
   final HeroType heroType;
+  final StreamController<DraggableScrollBarEvent> _draggableScrollBarEventStreamController = StreamController.broadcast();
 
-  const FilterGridPage({
+  FilterGridPage({
     Key? key,
     this.settingsRouteKey,
     required this.appBar,
@@ -73,7 +76,12 @@ class FilterGridPage<T extends CollectionFilter> extends StatelessWidget {
       child: Selector<Settings, bool>(
         selector: (context, s) => s.showBottomNavigationBar,
         builder: (context, showBottomNavigationBar, child) {
-          return Scaffold(
+          return NotificationListener<DraggableScrollBarNotification>(
+            onNotification: (notification) {
+              _draggableScrollBarEventStreamController.add(notification.event);
+              return false;
+            },
+            child: Scaffold(
               body: WillPopScope(
                 onWillPop: () {
                   final selection = context.read<Selection<FilterGridItem<T>>>();
@@ -108,9 +116,14 @@ class FilterGridPage<T extends CollectionFilter> extends StatelessWidget {
                 ),
               ),
               drawer: const AppDrawer(),
-            bottomNavigationBar: showBottomNavigationBar ? const AppBottomNavBar() : null,
+              bottomNavigationBar: showBottomNavigationBar
+                  ? AppBottomNavBar(
+                      events: _draggableScrollBarEventStreamController.stream,
+                    )
+                  : null,
               resizeToAvoidBottomInset: false,
               extendBody: true,
+            ),
           );
         },
       ),

lib/widgets/navigation/nav_bar/floating.dart

@@ -1,12 +1,17 @@
+import 'dart:async';
+
+import 'package:aves/widgets/common/basic/draggable_scrollbar.dart';
 import 'package:flutter/material.dart';
 
 class FloatingNavBar extends StatefulWidget {
   final ScrollController? scrollController;
+  final Stream<DraggableScrollBarEvent> events;
   final Widget child;
 
   const FloatingNavBar({
     Key? key,
     required this.scrollController,
+    required this.events,
     required this.child,
   }) : super(key: key);
 
@@ -15,10 +20,12 @@ class FloatingNavBar extends StatefulWidget {
 }
 
 class _FloatingNavBarState extends State<FloatingNavBar> with SingleTickerProviderStateMixin {
+  final List<StreamSubscription> _subscriptions = [];
   late AnimationController _controller;
   late Animation<Offset> _offsetAnimation;
   double? _lastOffset;
   double _delta = 0;
+  bool _isDragging = false;
 
   static const double _deltaThreshold = 50;
 
@@ -64,10 +71,14 @@ class _FloatingNavBarState extends State<FloatingNavBar> with SingleTickerProvid
     _lastOffset = null;
     _delta = 0;
     widget.scrollController?.addListener(_onScrollChange);
+    _subscriptions.add(widget.events.listen(_onDraggableScrollBarEvent));
   }
 
   void _unregisterWidget(FloatingNavBar widget) {
     widget.scrollController?.removeListener(_onScrollChange);
+    _subscriptions
+      ..forEach((sub) => sub.cancel())
+      ..clear();
   }
 
   @override
@@ -79,6 +90,8 @@ class _FloatingNavBarState extends State<FloatingNavBar> with SingleTickerProvid
   }
 
   void _onScrollChange() {
+    if (_isDragging) return;
+
     final scrollController = widget.scrollController;
     if (scrollController == null) return;
 
@@ -88,13 +101,28 @@ class _FloatingNavBarState extends State<FloatingNavBar> with SingleTickerProvid
 
     if (_delta.abs() > _deltaThreshold) {
       if (_delta > 0) {
-        // hide
+        _hide();
-        _controller.forward();
       } else {
-        // show
+        _show();
-        _controller.reverse();
       }
       _delta = 0;
     }
   }
+
+  void _onDraggableScrollBarEvent(DraggableScrollBarEvent event) {
+    switch (event) {
+      case DraggableScrollBarEvent.dragStart:
+        _isDragging = true;
+        _hide();
+        break;
+      case DraggableScrollBarEvent.dragEnd:
+        _isDragging = false;
+        _show();
+        break;
+    }
+  }
+
+  void _show() => _controller.reverse();
+
+  void _hide() => _controller.forward();
 }

lib/widgets/navigation/nav_bar/nav_bar.dart

@@ -4,6 +4,7 @@ import 'package:aves/model/settings/settings.dart';
 import 'package:aves/model/source/collection_lens.dart';
 import 'package:aves/model/source/collection_source.dart';
 import 'package:aves/widgets/collection/collection_page.dart';
+import 'package:aves/widgets/common/basic/draggable_scrollbar.dart';
 import 'package:aves/widgets/common/extensions/build_context.dart';
 import 'package:aves/widgets/common/fx/blurred.dart';
 import 'package:aves/widgets/filter_grids/albums_page.dart';
@@ -14,11 +15,13 @@ import 'package:flutter/material.dart';
 import 'package:provider/provider.dart';
 
 class AppBottomNavBar extends StatelessWidget {
+  final Stream<DraggableScrollBarEvent> events;
   // collection loaded in the `CollectionPage`, if any
   final CollectionLens? currentCollection;
 
   const AppBottomNavBar({
     Key? key,
+    required this.events,
     this.currentCollection,
   }) : super(key: key);
 
@@ -73,6 +76,7 @@ class AppBottomNavBar extends StatelessWidget {
       },
       child: FloatingNavBar(
         scrollController: PrimaryScrollController.of(context),
+        events: events,
         child: SafeArea(
           child: child,
         ),