Exposed EdgeDraggingAutoScroller velocityScalar to ReorderableList (#124459)

Exposed EdgeDraggingAutoScroller velocityScalar to ReorderableList

packages/flutter/lib/src/material/reorderable_list.dart

@@ -83,6 +83,7 @@ class ReorderableListView extends StatefulWidget {
     this.keyboardDismissBehavior = ScrollViewKeyboardDismissBehavior.manual,
     this.restorationId,
     this.clipBehavior = Clip.hardEdge,
+    this.autoScrollerVelocityScalar,
   }) : assert(
          itemExtent == null || prototypeItem == null,
          'You can only pass itemExtent or prototypeItem, not both',
@@ -148,6 +149,7 @@ class ReorderableListView extends StatefulWidget {
     this.keyboardDismissBehavior = ScrollViewKeyboardDismissBehavior.manual,
     this.restorationId,
     this.clipBehavior = Clip.hardEdge,
+    this.autoScrollerVelocityScalar,
   }) : assert(itemCount >= 0),
        assert(
          itemExtent == null || prototypeItem == null,
@@ -259,6 +261,9 @@ class ReorderableListView extends StatefulWidget {
   /// {@macro flutter.widgets.list_view.prototypeItem}
   final Widget? prototypeItem;
 
+  /// {@macro flutter.widgets.EdgeDraggingAutoScroller.velocityScalar}
+  final double? autoScrollerVelocityScalar;
+
   @override
   State<ReorderableListView> createState() => _ReorderableListViewState();
 }
@@ -428,6 +433,7 @@ class _ReorderableListViewState extends State<ReorderableListView> {
             onReorderStart: widget.onReorderStart,
             onReorderEnd: widget.onReorderEnd,
             proxyDecorator: widget.proxyDecorator ?? _proxyDecorator,
+            autoScrollerVelocityScalar: widget.autoScrollerVelocityScalar,
           ),
         ),
         if (widget.footer != null)

packages/flutter/lib/src/widgets/reorderable_list.dart

@@ -133,6 +133,7 @@ class ReorderableList extends StatefulWidget {
     this.keyboardDismissBehavior = ScrollViewKeyboardDismissBehavior.manual,
     this.restorationId,
     this.clipBehavior = Clip.hardEdge,
+    this.autoScrollerVelocityScalar,
   }) : assert(itemCount >= 0),
        assert(
          itemExtent == null || prototypeItem == null,
@@ -255,6 +256,9 @@ class ReorderableList extends StatefulWidget {
   /// {@macro flutter.widgets.list_view.prototypeItem}
   final Widget? prototypeItem;
 
+  /// {@macro flutter.widgets.EdgeDraggingAutoScroller.velocityScalar}
+  final double? autoScrollerVelocityScalar;
+
   /// The state from the closest instance of this class that encloses the given
   /// context.
   ///
@@ -400,6 +404,7 @@ class ReorderableListState extends State<ReorderableList> {
             onReorderStart: widget.onReorderStart,
             onReorderEnd: widget.onReorderEnd,
             proxyDecorator: widget.proxyDecorator,
+            autoScrollerVelocityScalar: widget.autoScrollerVelocityScalar,
           ),
         ),
       ],
@@ -445,6 +450,7 @@ class SliverReorderableList extends StatefulWidget {
     this.itemExtent,
     this.prototypeItem,
     this.proxyDecorator,
+    this.autoScrollerVelocityScalar,
   }) : assert(itemCount >= 0),
        assert(
          itemExtent == null || prototypeItem == null,
@@ -478,6 +484,9 @@ class SliverReorderableList extends StatefulWidget {
   /// {@macro flutter.widgets.list_view.prototypeItem}
   final Widget? prototypeItem;
 
+  /// {@macro flutter.widgets.EdgeDraggingAutoScroller.velocityScalar}
+  final double? autoScrollerVelocityScalar;
+
   @override
   SliverReorderableListState createState() => SliverReorderableListState();
 
@@ -613,7 +622,8 @@ class SliverReorderableListState extends State<SliverReorderableList> with Ticke
       _autoScroller?.stopAutoScroll();
       _autoScroller = EdgeDraggingAutoScroller(
         _scrollable,
-        onScrollViewScrolled: _handleScrollableAutoScrolled
+        onScrollViewScrolled: _handleScrollableAutoScrolled,
+        velocityScalar: widget.autoScrollerVelocityScalar,
       );
     }
   }
@@ -624,6 +634,15 @@ class SliverReorderableListState extends State<SliverReorderableList> with Ticke
     if (widget.itemCount != oldWidget.itemCount) {
       cancelReorder();
     }
+
+    if (widget.autoScrollerVelocityScalar != oldWidget.autoScrollerVelocityScalar) {
+      _autoScroller?.stopAutoScroll();
+      _autoScroller = EdgeDraggingAutoScroller(
+        _scrollable,
+        onScrollViewScrolled: _handleScrollableAutoScrolled,
+        velocityScalar: widget.autoScrollerVelocityScalar,
+      );
+    }
   }
 
   @override

packages/flutter/lib/src/widgets/scrollable_helpers.dart

@@ -160,8 +160,8 @@ class EdgeDraggingAutoScroller {
   EdgeDraggingAutoScroller(
     this.scrollable, {
     this.onScrollViewScrolled,
-    this.velocityScalar = _kDefaultAutoScrollVelocityScalar,
-  });
+    double? velocityScalar,
+  }): velocityScalar = velocityScalar ?? _kDefaultAutoScrollVelocityScalar;
 
   // An eyeballed value for a smooth scrolling experience.
   static const double _kDefaultAutoScrollVelocityScalar = 7;
@@ -176,10 +176,14 @@ class EdgeDraggingAutoScroller {
   /// in between each scroll.
   final VoidCallback? onScrollViewScrolled;
 
+  /// {@template flutter.widgets.EdgeDraggingAutoScroller.velocityScalar}
   /// The velocity scalar per pixel over scroll.
   ///
   /// It represents how the velocity scale with the over scroll distance. The
   /// auto-scroll velocity = <distance of overscroll> * velocityScalar.
+  ///
+  /// Defaults to 7 if not set or set to null.
+  /// {@endtemplate}
   final double velocityScalar;
 
   late Rect _dragTargetRelatedToScrollOrigin;

packages/flutter/test/material/reorderable_list_test.dart

@@ -1779,6 +1779,88 @@ void main() {
     expect(item1Height, 30.0);
     expect(item2Height, 30.0);
   });
+
+  testWidgets('ReorderableListView auto scrolls speed is configurable', (WidgetTester tester) async {
+    Future<void> pumpFor({
+      required Duration duration,
+      Duration interval = const Duration(milliseconds: 50),
+    }) async {
+      await tester.pump();
+
+      int times = (duration.inMilliseconds / interval.inMilliseconds).ceil();
+      while (times > 0) {
+        await tester.pump(interval + const Duration(milliseconds: 1));
+        await tester.idle();
+        times--;
+      }
+    }
+
+    Future<double> pumpListAndDrag({required double autoScrollerVelocityScalar}) async {
+      final List<int> items = List<int>.generate(10, (int index) => index);
+      final ScrollController scrollController = ScrollController();
+
+      await tester.pumpWidget(
+        MaterialApp(
+          home: ReorderableListView.builder(
+            itemBuilder: (BuildContext context, int index) {
+              return Container(
+                key: ValueKey<int>(items[index]),
+                height: 100,
+                color: items[index].isOdd ? Colors.red : Colors.green,
+                child: ReorderableDragStartListener(
+                  index: index,
+                  child: Row(
+                    crossAxisAlignment: CrossAxisAlignment.start,
+                    children: <Widget>[
+                      Text('item ${items[index]}'),
+                      const Icon(Icons.drag_handle),
+                    ],
+                  ),
+                ),
+              );
+            },
+            itemCount: items.length,
+            onReorder: (int fromIndex, int toIndex) {},
+            scrollController: scrollController,
+            autoScrollerVelocityScalar: autoScrollerVelocityScalar,
+          ),
+        ),
+      );
+
+      expect(scrollController.offset, 0);
+
+      final Finder item = find.text('item 0');
+      final TestGesture drag = await tester.startGesture(tester.getCenter(item));
+
+      // Drag just enough to touch the edge but not surpass it, so the
+      // auto scroller is not yet triggered
+      await drag.moveBy(const Offset(0, 500));
+      await pumpFor(duration: const Duration(milliseconds: 200));
+
+      expect(scrollController.offset, 0);
+
+      // Now drag a little bit more so the auto scroller triggers
+      await drag.moveBy(const Offset(0, 50));
+      await pumpFor(
+        duration: const Duration(milliseconds: 600),
+        interval: Duration(milliseconds: (1000 / autoScrollerVelocityScalar).round()),
+      );
+
+      return scrollController.offset;
+    }
+
+    const double fastVelocityScalar = 20;
+    final double offsetForFastScroller = await pumpListAndDrag(autoScrollerVelocityScalar: fastVelocityScalar);
+
+    // Reset widget tree
+    await tester.pumpWidget(const SizedBox());
+
+    const double slowVelocityScalar = 5;
+    final double offsetForSlowScroller = await pumpListAndDrag(autoScrollerVelocityScalar: slowVelocityScalar);
+
+    expect(offsetForFastScroller / offsetForSlowScroller, fastVelocityScalar / slowVelocityScalar);
+  });
+
 }
 
 Future<void> longPressDrag(WidgetTester tester, Offset start, Offset end) async {

packages/flutter/test/widgets/reorderable_list_test.dart

@@ -1223,6 +1223,91 @@ void main() {
 
     expect(item0, findsNothing);
   });
+
+  testWidgets('SliverReorderableList auto scrolls speed is configurable', (WidgetTester tester) async {
+    Future<void> pumpFor({
+      required Duration duration,
+      Duration interval = const Duration(milliseconds: 50),
+    }) async {
+      await tester.pump();
+
+      int times = (duration.inMilliseconds / interval.inMilliseconds).ceil();
+      while (times > 0) {
+        await tester.pump(interval + const Duration(milliseconds: 1));
+        await tester.idle();
+        times--;
+      }
+    }
+
+    Future<double> pumpListAndDrag({required double autoScrollerVelocityScalar}) async {
+      final List<int> items = List<int>.generate(10, (int index) => index);
+      final ScrollController scrollController = ScrollController();
+
+      await tester.pumpWidget(
+        MaterialApp(
+          home: CustomScrollView(
+            controller: scrollController,
+            slivers: <Widget>[
+              SliverReorderableList(
+                itemBuilder: (BuildContext context, int index) {
+                  return Container(
+                    key: ValueKey<int>(items[index]),
+                    height: 100,
+                    color: items[index].isOdd ? Colors.red : Colors.green,
+                    child: ReorderableDragStartListener(
+                      index: index,
+                      child: Row(
+                        crossAxisAlignment: CrossAxisAlignment.start,
+                        children: <Widget>[
+                          Text('item ${items[index]}'),
+                          const Icon(Icons.drag_handle),
+                        ],
+                      ),
+                    ),
+                  );
+                },
+                itemCount: items.length,
+                onReorder: (int fromIndex, int toIndex) {},
+                autoScrollerVelocityScalar: autoScrollerVelocityScalar,
+              ),
+            ],
+          ),
+        ),
+      );
+
+      expect(scrollController.offset, 0);
+
+      final Finder item = find.text('item 0');
+      final TestGesture drag = await tester.startGesture(tester.getCenter(item));
+
+      // Drag just enough to touch the edge but not surpass it, so the
+      // auto scroller is not yet triggered
+      await drag.moveBy(const Offset(0, 500));
+      await pumpFor(duration: const Duration(milliseconds: 200));
+
+      expect(scrollController.offset, 0);
+
+      // Now drag a little bit more so the auto scroller triggers
+      await drag.moveBy(const Offset(0, 50));
+      await pumpFor(
+        duration: const Duration(milliseconds: 600),
+        interval: Duration(milliseconds: (1000 / autoScrollerVelocityScalar).round()),
+      );
+
+      return scrollController.offset;
+    }
+
+    const double fastVelocityScalar = 20;
+    final double offsetForFastScroller = await pumpListAndDrag(autoScrollerVelocityScalar: fastVelocityScalar);
+
+    // Reset widget tree
+    await tester.pumpWidget(const SizedBox());
+
+    const double slowVelocityScalar = 5;
+    final double offsetForSlowScroller = await pumpListAndDrag(autoScrollerVelocityScalar: slowVelocityScalar);
+
+    expect(offsetForFastScroller / offsetForSlowScroller, fastVelocityScalar / slowVelocityScalar);
+  });
 }
 
 class TestList extends StatelessWidget {
@@ -1235,6 +1320,7 @@ class TestList extends StatelessWidget {
     this.reverse = false,
     this.onReorderStart,
     this.onReorderEnd,
+    this.autoScrollerVelocityScalar,
   });
 
   final List<int> items;
@@ -1243,6 +1329,7 @@ class TestList extends StatelessWidget {
   final ReorderItemProxyDecorator? proxyDecorator;
   final bool reverse;
   final void Function(int)? onReorderStart, onReorderEnd;
+  final double? autoScrollerVelocityScalar;
 
   @override
   Widget build(BuildContext context) {
@@ -1288,6 +1375,7 @@ class TestList extends StatelessWidget {
                       proxyDecorator: proxyDecorator,
                       onReorderStart: onReorderStart,
                       onReorderEnd: onReorderEnd,
+                      autoScrollerVelocityScalar: autoScrollerVelocityScalar,
                     ),
                   ],
                 );