albums/countries/tags: added fast scroll

lib/widgets/filter_grids/common/filter_grid_page.dart

@@ -15,6 +15,7 @@ import 'package:aves/widgets/common/data_providers/media_query_data_provider.dar
 import 'package:aves/widgets/common/double_back_pop.dart';
 import 'package:aves/widgets/common/icons.dart';
 import 'package:aves/widgets/common/menu_row.dart';
+import 'package:aves/widgets/common/scroll_thumb.dart';
 import 'package:aves/widgets/common/search_button.dart';
 import 'package:aves/widgets/drawer/app_drawer.dart';
 import 'package:aves/widgets/filter_grids/common/chip_action_delegate.dart';
@@ -22,6 +23,7 @@ import 'package:aves/widgets/filter_grids/common/chip_actions.dart';
 import 'package:aves/widgets/filter_grids/common/chip_set_action_delegate.dart';
 import 'package:aves/widgets/filter_grids/common/decorated_filter_chip.dart';
 import 'package:collection/collection.dart';
+import 'package:draggable_scrollbar/draggable_scrollbar.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_staggered_animations/flutter_staggered_animations.dart';
 import 'package:pedantic/pedantic.dart';
@@ -168,7 +170,6 @@ class FilterGridPage extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    final pinnedFilters = settings.pinnedFilters;
     return MediaQueryDataProvider(
       child: Scaffold(
         body: DoubleBackPopScope(
@@ -177,8 +178,47 @@ class FilterGridPage extends StatelessWidget {
               selector: (c, mq) => mq.size.width,
               builder: (c, mqWidth, child) {
                 final columnCount = (mqWidth / maxCrossAxisExtent).ceil();
+                final scrollView = _buildScrollView(context, columnCount);
                 return AnimationLimiter(
-                  child: CustomScrollView(
+                  child: _buildDraggableScrollView(scrollView),
+                );
+              },
+            ),
+          ),
+        ),
+        drawer: AppDrawer(
+          source: source,
+        ),
+        resizeToAvoidBottomInset: false,
+      ),
+    );
+  }
+
+  Widget _buildDraggableScrollView(ScrollView scrollView) {
+    return Selector<MediaQueryData, double>(
+      selector: (context, mq) => mq.viewInsets.bottom,
+      builder: (context, mqViewInsetsBottom, child) => DraggableScrollbar(
+        heightScrollThumb: avesScrollThumbHeight,
+        backgroundColor: Colors.white,
+        scrollThumbBuilder: avesScrollThumbBuilder(
+          height: avesScrollThumbHeight,
+          backgroundColor: Colors.white,
+        ),
+        controller: PrimaryScrollController.of(context),
+        padding: EdgeInsets.only(
+          // padding to keep scroll thumb between app bar above and nav bar below
+          top: kToolbarHeight,
+          bottom: mqViewInsetsBottom,
+        ),
+        child: scrollView,
+      ),
+    );
+  }
+
+  ScrollView _buildScrollView(BuildContext context, int columnCount) {
+    final pinnedFilters = settings.pinnedFilters;
+    return CustomScrollView(
+      controller: PrimaryScrollController.of(context),
       slivers: [
         appBar,
         filterKeys.isEmpty
@@ -233,17 +273,6 @@ class FilterGridPage extends StatelessWidget {
           ),
         ),
       ],
-                  ),
-                );
-              },
-            ),
-          ),
-        ),
-        drawer: AppDrawer(
-          source: source,
-        ),
-        resizeToAvoidBottomInset: false,
-      ),
     );
   }
 }