From 418fa9d62610b6990f18c0a7cf6c194364fad4b8 Mon Sep 17 00:00:00 2001
From: Callum Moffat <smartercallum@gmail.com>
Date: Mon, 26 Aug 2024 18:32:22 -0400
Subject: [PATCH] Optimize out LayoutBuilder from ReorderableList children
 (#153987)

PR #147863 used a `LayoutBuilder` to ensure `ReorderableList` proxy items are built with the same constraints as their normal counterparts. However we don't actually need the `LayoutBuilder`, we can just grab the constraints from the `RenderBox` at proxy-creation-time.
---
 .../lib/src/widgets/reorderable_list.dart        | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/packages/flutter/lib/src/widgets/reorderable_list.dart b/packages/flutter/lib/src/widgets/reorderable_list.dart
index f7aaf7bf3c7..9acef853017 100644
--- a/packages/flutter/lib/src/widgets/reorderable_list.dart
+++ b/packages/flutter/lib/src/widgets/reorderable_list.dart
@@ -14,7 +14,6 @@ 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';
@@ -1087,8 +1086,6 @@ class _ReorderableItemState extends State<_ReorderableItem> {
     }
   }
   bool _dragging = false;
-  BoxConstraints? get childLayoutConstraints => _childLayoutConstraints;
-  BoxConstraints? _childLayoutConstraints;
 
   @override
   void initState() {
@@ -1120,13 +1117,10 @@ class _ReorderableItemState extends State<_ReorderableItem> {
       return SizedBox.fromSize(size: size);
     }
     _listState._registerItem(this);
-    return LayoutBuilder(builder: (BuildContext context, BoxConstraints constraints) {
-      _childLayoutConstraints = constraints;
-      return Transform(
-        transform: Matrix4.translationValues(offset.dx, offset.dy, 0.0),
-        child: widget.child,
-      );
-    });
+    return Transform.translate(
+      offset: offset,
+      child: widget.child,
+    );
   }
 
   @override
@@ -1346,7 +1340,7 @@ class _DragInfo extends Drag {
     dragOffset = itemRenderBox.globalToLocal(initialPosition);
     itemSize = item.context.size!;
     itemExtent = _sizeExtent(itemSize, scrollDirection);
-    itemLayoutConstraints = item.childLayoutConstraints!;
+    itemLayoutConstraints = itemRenderBox.constraints;
     scrollable = Scrollable.of(item.context);
   }