Clear the cached data of RenderBox if its parent re-layout (#101493)

engine-flutter-autoroll · May 6, 2022 · 82afe3e · 82afe3e
1 parent 55881f7
commit 82afe3e
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Showing 2 changed files with 87 additions and 6 deletions.
diff --git a/packages/flutter/lib/src/rendering/box.dart b/packages/flutter/lib/src/rendering/box.dart
@@ -2348,8 +2348,7 @@ abstract class RenderBox extends RenderObject {
     }());
   }
 
-  @override
-  void markNeedsLayout() {
+  bool _clearCachedData() {
     if ((_cachedBaselines != null && _cachedBaselines!.isNotEmpty) ||
         (_cachedIntrinsicDimensions != null && _cachedIntrinsicDimensions!.isNotEmpty) ||
         (_cachedDryLayoutSizes != null && _cachedDryLayoutSizes!.isNotEmpty)) {
@@ -2361,14 +2360,30 @@ abstract class RenderBox extends RenderObject {
       _cachedBaselines?.clear();
       _cachedIntrinsicDimensions?.clear();
       _cachedDryLayoutSizes?.clear();
-      if (parent is RenderObject) {
-        markParentNeedsLayout();
-        return;
-      }
+      return true;
+    }
+    return false;
+  }
+
+  @override
+  void markNeedsLayout() {
+    if (_clearCachedData() && parent is RenderObject) {
+      markParentNeedsLayout();
+      return;
     }
     super.markNeedsLayout();
   }
 
+  @override
+  void layout(Constraints constraints, {bool parentUsesSize = false}) {
+    if (hasSize && constraints != this.constraints &&
+        _cachedBaselines != null && _cachedBaselines!.isNotEmpty) {
+      // The cached baselines data may need update if the constraints change.
+      _cachedBaselines?.clear();
+    }
+    super.layout(constraints, parentUsesSize: parentUsesSize);
+  }
+
   /// {@macro flutter.rendering.RenderObject.performResize}
   ///
   /// By default this method sets [size] to the result of [computeDryLayout]

diff --git a/packages/flutter/test/rendering/cached_intrinsics_test.dart b/packages/flutter/test/rendering/cached_intrinsics_test.dart
@@ -5,7 +5,11 @@
 import 'package:flutter/rendering.dart';
 import 'package:flutter_test/flutter_test.dart';
 
+import 'rendering_tester.dart';
+
 class RenderTestBox extends RenderBox {
+  late Size boxSize;
+  int calls = 0;
   double value = 0.0;
   double next() {
     value += 1.0;
@@ -19,9 +23,23 @@ class RenderTestBox extends RenderBox {
   double computeMinIntrinsicHeight(double width) => next();
   @override
   double computeMaxIntrinsicHeight(double width) => next();
+
+  @override
+  void performLayout() {
+    size = constraints.biggest;
+    boxSize = size;
+  }
+
+  @override
+  double? computeDistanceToActualBaseline(TextBaseline baseline) {
+    calls += 1;
+    return boxSize.height / 2.0;
+  }
 }
 
 void main() {
+  TestRenderingFlutterBinding.ensureInitialized();
+
   test('Intrinsics cache', () {
     final RenderBox test = RenderTestBox();
 
@@ -68,4 +86,52 @@ void main() {
     expect(test.getMinIntrinsicWidth(0.0), equals(1.0));
 
   });
+
+  // Regression test for https://github.com/flutter/flutter/issues/101179
+  test('Cached baselines should be cleared if its parent re-layout', () {
+    double viewHeight =  200.0;
+    final RenderTestBox test = RenderTestBox();
+    final RenderBox baseline = RenderBaseline(
+      baseline: 0.0,
+      baselineType: TextBaseline.alphabetic,
+      child: test,
+    );
+    final RenderConstrainedBox root = RenderConstrainedBox(
+      additionalConstraints: BoxConstraints.tightFor(width: 200.0, height: viewHeight),
+      child: baseline,
+    );
+
+    layout(RenderPositionedBox(
+      child: root,
+    ));
+
+    BoxParentData? parentData = test.parentData as BoxParentData?;
+    expect(parentData!.offset.dy, -(viewHeight / 2.0));
+    expect(test.calls, 1);
+
+    // Trigger the root render re-layout.
+    viewHeight = 300.0;
+    root.additionalConstraints = BoxConstraints.tightFor(width: 200.0, height: viewHeight);
+    pumpFrame();
+
+    parentData = test.parentData as BoxParentData?;
+    expect(parentData!.offset.dy, -(viewHeight / 2.0));
+    expect(test.calls, 2); // The layout constraints change will clear the cached data.
+
+    final RenderObject parent = test.parent! as RenderObject;
+    expect(parent.debugNeedsLayout, false);
+
+    // Do not forget notify parent dirty after the cached data be cleared by `layout()`
+    test.markNeedsLayout();
+    expect(parent.debugNeedsLayout, true);
+
+    pumpFrame();
+    expect(parent.debugNeedsLayout, false);
+    expect(test.calls, 3); // Self dirty will clear the cached data.
+
+    parent.markNeedsLayout();
+    pumpFrame();
+
+    expect(test.calls, 3); // Use the cached data if the layout constraints do not change.
+  });
 }