Maintain the same layout constraints for item in the ReorderableList during dragging as before dragging. (#147863)

Fixes #147419

Author: yiiim

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

@@ -11,6 +11,7 @@ import 'basic.dart';
 import 'debug.dart';
 import 'framework.dart';
 import 'inherited_theme.dart';
+import 'layout_builder.dart';
 import 'localizations.dart';
 import 'media_query.dart';
 import 'overlay.dart';
@@ -1083,6 +1084,8 @@ class _ReorderableItemState extends State<_ReorderableItem> {
     }
   }
   bool _dragging = false;
+  BoxConstraints? get childLayoutConstraints => _childLayoutConstraints;
+  BoxConstraints? _childLayoutConstraints;
 
   @override
   void initState() {
@@ -1114,10 +1117,13 @@ class _ReorderableItemState extends State<_ReorderableItem> {
       return SizedBox.fromSize(size: size);
     }
     _listState._registerItem(this);
-    return Transform(
-      transform: Matrix4.translationValues(offset.dx, offset.dy, 0.0),
-      child: widget.child,
-    );
+    return LayoutBuilder(builder: (BuildContext context, BoxConstraints constraints) {
+      _childLayoutConstraints = constraints;
+      return Transform(
+        transform: Matrix4.translationValues(offset.dx, offset.dy, 0.0),
+        child: widget.child,
+      );
+    });
   }
 
   @override
@@ -1337,6 +1343,7 @@ class _DragInfo extends Drag {
     dragOffset = itemRenderBox.globalToLocal(initialPosition);
     itemSize = item.context.size!;
     itemExtent = _sizeExtent(itemSize, scrollDirection);
+    itemLayoutConstraints = item.childLayoutConstraints!;
     scrollable = Scrollable.of(item.context);
   }
 
@@ -1354,6 +1361,7 @@ class _DragInfo extends Drag {
   late Offset dragPosition;
   late Offset dragOffset;
   late Size itemSize;
+  late BoxConstraints itemLayoutConstraints;
   late double itemExtent;
   late CapturedThemes capturedThemes;
   ScrollableState? scrollable;
@@ -1411,6 +1419,7 @@ class _DragInfo extends Drag {
         listState: listState,
         index: index,
         size: itemSize,
+        constraints: itemLayoutConstraints,
         animation: _proxyAnimation!,
         position: dragPosition - dragOffset - _overlayOrigin(context),
         proxyDecorator: proxyDecorator,
@@ -1433,6 +1442,7 @@ class _DragItemProxy extends StatelessWidget {
     required this.child,
     required this.position,
     required this.size,
+    required this.constraints,
     required this.animation,
     required this.proxyDecorator,
   });
@@ -1442,6 +1452,7 @@ class _DragItemProxy extends StatelessWidget {
   final Widget child;
   final Offset position;
   final Size size;
+  final BoxConstraints constraints;
   final AnimationController animation;
   final ReorderItemProxyDecorator? proxyDecorator;
 
@@ -1468,7 +1479,14 @@ class _DragItemProxy extends StatelessWidget {
             child: SizedBox(
               width: size.width,
               height: size.height,
-              child: child,
+              child: OverflowBox(
+                minWidth: constraints.minWidth,
+                minHeight: constraints.minHeight,
+                maxWidth: constraints.maxWidth,
+                maxHeight: constraints.maxHeight,
+                alignment: listState._scrollDirection == Axis.horizontal ? Alignment.centerLeft : Alignment.topCenter,
+                child: child,
+              ),
             ),
           );
         },

packages/flutter/test/widgets/reorderable_list_test.dart

@@ -1528,6 +1528,48 @@ void main() {
     await testFor(prototypeItem: const SizedBox(height: 100, width: 100, child: Text('prototype')));
     await testFor(itemExtent: 100);
   });
+
+  testWidgets('The item being dragged will not be affected by layout constraints.', (WidgetTester tester) async {
+    final Map<int, BoxConstraints> itemLayoutConstraints = <int, BoxConstraints>{};
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Scaffold(
+          body: CustomScrollView(
+            slivers: <Widget>[
+              SliverReorderableList(
+                itemBuilder: (BuildContext context, int index) {
+                  return LayoutBuilder(
+                    key: ValueKey<int>(index),
+                    builder: (BuildContext context, BoxConstraints constraints) {
+                      itemLayoutConstraints[index] = constraints;
+                      return SizedBox(
+                        height: 100,
+                        child: ReorderableDragStartListener(
+                          index: index,
+                          child: Text('$index'),
+                        ),
+                      );
+                    }
+                  );
+                },
+                itemCount: 5,
+                onReorder: (int fromIndex, int toIndex) {},
+              ),
+            ],
+          ),
+        ),
+      ),
+    );
+    final Map<int, BoxConstraints> preDragLayoutConstraints = Map<int, BoxConstraints>.of(itemLayoutConstraints);
+    itemLayoutConstraints.clear();
+    final TestGesture drag = await tester.startGesture(tester.getCenter(find.text('0')));
+    await tester.pump(kLongPressTimeout);
+    await drag.moveBy(const Offset(0, 20));
+    await tester.pump();
+    expect(itemLayoutConstraints, preDragLayoutConstraints);
+    await drag.up();
+    await tester.pumpAndSettle();
+  });
 }
 
 class TestList extends StatelessWidget {