From 4e89ccfdee314733570872c8f3fac35d0924194c Mon Sep 17 00:00:00 2001
From: Ayush Bherwani <ayush.bherwani1998@gmail.com>
Date: Tue, 15 Sep 2020 06:32:05 +0530
Subject: [PATCH] [LayoutBuilder] Implements baseline logic to pass baseline to
 child (#65000)

---
 .../lib/src/widgets/layout_builder.dart       |  7 ++++++
 .../flutter/test/widgets/baseline_test.dart   | 22 ++++++++++++++++++-
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/packages/flutter/lib/src/widgets/layout_builder.dart b/packages/flutter/lib/src/widgets/layout_builder.dart
index 558a9a3918..7936fd3cf6 100644
--- a/packages/flutter/lib/src/widgets/layout_builder.dart
+++ b/packages/flutter/lib/src/widgets/layout_builder.dart
@@ -361,6 +361,13 @@ class _RenderLayoutBuilder extends RenderBox with RenderObjectWithChildMixin<Ren
     }
   }
 
+  @override
+  double computeDistanceToActualBaseline(TextBaseline baseline) {
+    if (child != null)
+      return child.getDistanceToActualBaseline(baseline);
+    return super.computeDistanceToActualBaseline(baseline);
+  }
+
   @override
   bool hitTestChildren(BoxHitTestResult result, { Offset position }) {
     return child?.hitTest(result, position: position) ?? false;
diff --git a/packages/flutter/test/widgets/baseline_test.dart b/packages/flutter/test/widgets/baseline_test.dart
index 981a5e00d1..1a485830a3 100644
--- a/packages/flutter/test/widgets/baseline_test.dart
+++ b/packages/flutter/test/widgets/baseline_test.dart
@@ -93,6 +93,26 @@ void main() {
     await tester.pump();
     expect(calls, 2);
   });
+
+  testWidgets('LayoutBuilder returns child\'s baseline', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Material(
+          child: Baseline(
+            baseline: 180.0,
+            baselineType: TextBaseline.alphabetic,
+            child: LayoutBuilder(
+              builder: (BuildContext context, BoxConstraints constraints) {
+                return BaselineDetector(() {});
+              },
+            ),
+          ),
+        ),
+      ),
+    );
+
+    expect(tester.getRect(find.byType(BaselineDetector)).top, 160.0);
+  });
 }
 
 class BaselineDetector extends LeafRenderObjectWidget {
@@ -133,7 +153,7 @@ class RenderBaselineDetector extends RenderBox {
   double computeDistanceToActualBaseline(TextBaseline baseline) {
     if (callback != null)
       callback();
-    return 0.0;
+    return 20.0;
   }
 
   void dirty() {