Implement dryLayout for RenderAnimatedSize (#71097)

packages/flutter/lib/src/rendering/animated_size.dart

@@ -223,6 +223,38 @@ class RenderAnimatedSize extends RenderAligningShiftedBox {
       _hasVisualOverflow = true;
   }
 
+  @override
+  Size computeDryLayout(BoxConstraints constraints) {
+    if (child == null || constraints.isTight) {
+      return constraints.smallest;
+    }
+
+    // This simplified version of performLayout only calculates the current
+    // size without modifying global state. See performLayout for comments
+    // explaining the rational behind the implementation.
+    final Size childSize = child!.getDryLayout(constraints);
+    assert(_state != null);
+    switch (_state) {
+      case RenderAnimatedSizeState.start:
+        return constraints.constrain(childSize);
+      case RenderAnimatedSizeState.stable:
+        if (_sizeTween.end != childSize) {
+          return constraints.constrain(size);
+        } else if (_controller.value == _controller.upperBound) {
+          return constraints.constrain(childSize);
+        }
+        break;
+      case RenderAnimatedSizeState.unstable:
+      case RenderAnimatedSizeState.changed:
+        if (_sizeTween.end != childSize) {
+          return constraints.constrain(childSize);
+        }
+        break;
+    }
+
+    return constraints.constrain(_animatedSize!);
+  }
+
   void _restartAnimation() {
     _lastValue = 0.0;
     _controller.forward(from: 0.0);

packages/flutter/lib/src/rendering/box.dart

@@ -1769,6 +1769,7 @@ abstract class RenderBox extends RenderObject {
   }
 
   Map<BoxConstraints, Size>? _cachedDryLayoutSizes;
+  bool _computingThisDryLayout = false;
 
   /// Returns the [Size] that this [RenderBox] would like to be given the
   /// provided [BoxConstraints].
@@ -1800,9 +1801,24 @@ abstract class RenderBox extends RenderObject {
     }());
     if (shouldCache) {
       _cachedDryLayoutSizes ??= <BoxConstraints, Size>{};
-      return _cachedDryLayoutSizes!.putIfAbsent(constraints, () => computeDryLayout(constraints));
+      return _cachedDryLayoutSizes!.putIfAbsent(constraints, () => _computeDryLayout(constraints));
     }
-    return computeDryLayout(constraints);
+    return _computeDryLayout(constraints);
+  }
+
+  Size _computeDryLayout(BoxConstraints constraints) {
+    assert(() {
+      assert(!_computingThisDryLayout);
+      _computingThisDryLayout = true;
+      return true;
+    }());
+    final Size result =  computeDryLayout(constraints);
+    assert(() {
+      assert(_computingThisDryLayout);
+      _computingThisDryLayout = false;
+      return true;
+    }());
+    return result;
   }
 
   /// Computes the value returned by [getDryLayout]. Do not call this
@@ -1907,7 +1923,7 @@ abstract class RenderBox extends RenderObject {
         assert(_size._owner == this);
         if (RenderObject.debugActiveLayout != null) {
           assert(
-            debugDoingThisResize || debugDoingThisLayout ||
+            debugDoingThisResize || debugDoingThisLayout || _computingThisDryLayout ||
               (RenderObject.debugActiveLayout == parent && _size._canBeUsedByParent),
             'RenderBox.size accessed beyond the scope of resize, layout, or '
             'permitted parent access. RenderBox can always access its own size, '

packages/flutter/test/widgets/animated_size_test.dart

@@ -315,5 +315,53 @@ void main() {
         expect(renderObject.clipBehavior, clip);
       }
     });
+
+    testWidgets('works wrapped in IntrinsicHeight and Wrap', (WidgetTester tester) async {
+      Future<void> pumpWidget(Size size, [Duration? duration]) async {
+        return tester.pumpWidget(
+          Center(
+            child: IntrinsicHeight(
+              child: Wrap(
+                textDirection: TextDirection.ltr,
+                children: <Widget>[
+                  AnimatedSize(
+                    duration: const Duration(milliseconds: 200),
+                    curve: Curves.easeInOutBack,
+                    vsync: tester,
+                    child: SizedBox(
+                      width: size.width,
+                      height: size.height,
+                    ),
+                  ),
+                ],
+              ),
+            ),
+          ),
+          duration,
+        );
+      }
+
+      await pumpWidget(const Size(100, 100));
+      expect(tester.renderObject<RenderBox>(find.byType(IntrinsicHeight)).size, const Size(100, 100));
+
+      await pumpWidget(const Size(150, 200));
+      expect(tester.renderObject<RenderBox>(find.byType(IntrinsicHeight)).size, const Size(100, 100));
+
+      // Each pump triggers verification of dry layout.
+      for (int total = 0; total < 200; total += 10) {
+        await tester.pump(const Duration(milliseconds: 10));
+      }
+      expect(tester.renderObject<RenderBox>(find.byType(IntrinsicHeight)).size, const Size(150, 200));
+
+      // Change every pump
+      await pumpWidget(const Size(100, 100));
+      expect(tester.renderObject<RenderBox>(find.byType(IntrinsicHeight)).size, const Size(150, 200));
+
+      await pumpWidget(const Size(111, 111), const Duration(milliseconds: 10));
+      expect(tester.renderObject<RenderBox>(find.byType(IntrinsicHeight)).size, const Size(111, 111));
+
+      await pumpWidget(const Size(222, 222), const Duration(milliseconds: 10));
+      expect(tester.renderObject<RenderBox>(find.byType(IntrinsicHeight)).size, const Size(222, 222));
+    });
   });
 }