From 0e9665e4ef59fca7d5c2eeed178cdd98d4a09fa0 Mon Sep 17 00:00:00 2001
From: chunhtai <47866232+chunhtai@users.noreply.github.com>
Date: Tue, 24 Aug 2021 18:09:04 -0700
Subject: [PATCH] Fixes listview shrinkwrap and hidden semantics node gets
 updated incorrectly. (#88814)

---
 .../flutter/lib/src/rendering/proxy_box.dart  |  1 -
 .../flutter/lib/src/rendering/viewport.dart   | 12 +++-
 .../flutter/test/widgets/list_view_test.dart  | 59 +++++++++++++++++++
 3 files changed, 69 insertions(+), 3 deletions(-)

diff --git a/packages/flutter/lib/src/rendering/proxy_box.dart b/packages/flutter/lib/src/rendering/proxy_box.dart
index e71f10bbbf3..8c39deae414 100644
--- a/packages/flutter/lib/src/rendering/proxy_box.dart
+++ b/packages/flutter/lib/src/rendering/proxy_box.dart
@@ -5056,7 +5056,6 @@ class RenderIndexedSemantics extends RenderProxyBox {
   @override
   void describeSemanticsConfiguration(SemanticsConfiguration config) {
     super.describeSemanticsConfiguration(config);
-    config.isSemanticBoundary = true;
     config.indexInParent = index;
   }
 
diff --git a/packages/flutter/lib/src/rendering/viewport.dart b/packages/flutter/lib/src/rendering/viewport.dart
index da9aeb739f6..3e32b4a2642 100644
--- a/packages/flutter/lib/src/rendering/viewport.dart
+++ b/packages/flutter/lib/src/rendering/viewport.dart
@@ -1920,6 +1920,14 @@ class RenderShrinkWrappingViewport extends RenderViewportBase<SliverLogicalConta
     _maxScrollExtent = 0.0;
     _shrinkWrapExtent = 0.0;
     _hasVisualOverflow = false;
+    switch (cacheExtentStyle) {
+      case CacheExtentStyle.pixel:
+        _calculatedCacheExtent = cacheExtent;
+        break;
+      case CacheExtentStyle.viewport:
+        _calculatedCacheExtent = mainAxisExtent * _cacheExtent;
+        break;
+    }
     return layoutChildSequence(
       child: firstChild,
       scrollOffset: math.max(0.0, correctedOffset),
@@ -1930,8 +1938,8 @@ class RenderShrinkWrappingViewport extends RenderViewportBase<SliverLogicalConta
       crossAxisExtent: crossAxisExtent,
       growthDirection: GrowthDirection.forward,
       advance: childAfter,
-      remainingCacheExtent: mainAxisExtent + 2 * _cacheExtent,
-      cacheOrigin: -_cacheExtent,
+      remainingCacheExtent: mainAxisExtent + 2 * _calculatedCacheExtent!,
+      cacheOrigin: -_calculatedCacheExtent!,
     );
   }
 
diff --git a/packages/flutter/test/widgets/list_view_test.dart b/packages/flutter/test/widgets/list_view_test.dart
index 66b0ae772ea..a4b06431a39 100644
--- a/packages/flutter/test/widgets/list_view_test.dart
+++ b/packages/flutter/test/widgets/list_view_test.dart
@@ -310,6 +310,65 @@ void main() {
     expect(find.text('19'), findsOneWidget);
   });
 
+  testWidgets('ListView with shrink wrap in bounded context correctly uses cache extent', (WidgetTester tester) async {
+    final SemanticsHandle handle = tester.ensureSemantics();
+    await tester.pumpWidget(
+      Directionality(
+        textDirection: TextDirection.ltr,
+        child: SizedBox(
+          height: 400,
+          child: ListView(
+            itemExtent: 100.0,
+            shrinkWrap: true,
+            children: List<Widget>.generate(20, (int i) {
+              return Text('Text $i');
+            }),
+          ),
+        ),
+      ),
+    );
+    expect(tester.getSemantics(find.text('Text 5')), matchesSemantics(isHidden: false));
+    expect(tester.getSemantics(find.text('Text 6', skipOffstage: false)), matchesSemantics(isHidden: true));
+    expect(tester.getSemantics(find.text('Text 7', skipOffstage: false)), matchesSemantics(isHidden: true));
+    expect(tester.getSemantics(find.text('Text 8', skipOffstage: false)), matchesSemantics(isHidden: true));
+    handle.dispose();
+  });
+
+  testWidgets('ListView hidden items should stay hidden if their semantics are updated', (WidgetTester tester) async {
+    final SemanticsHandle handle = tester.ensureSemantics();
+    await tester.pumpWidget(
+      Directionality(
+        textDirection: TextDirection.ltr,
+        child: SizedBox(
+          height: 400,
+          child: ListView(
+            itemExtent: 100.0,
+            shrinkWrap: true,
+            children: List<Widget>.generate(20, (int i) {
+              return Text('Text $i');
+            }),
+          ),
+        ),
+      ),
+    );
+    // Scrollable maybe be marked dirty after layout.
+    await tester.pumpAndSettle();
+    expect(tester.getSemantics(find.text('Text 5')), matchesSemantics(isHidden: false));
+    expect(tester.getSemantics(find.text('Text 6', skipOffstage: false)), matchesSemantics(isHidden: true));
+    expect(tester.getSemantics(find.text('Text 7', skipOffstage: false)), matchesSemantics(isHidden: true));
+    expect(tester.getSemantics(find.text('Text 8', skipOffstage: false)), matchesSemantics(isHidden: true));
+
+    // Marks Text 6 semantics as dirty.
+    final RenderObject text6 = tester.renderObject(find.text('Text 6', skipOffstage: false));
+    text6.markNeedsSemanticsUpdate();
+
+    // Verify the semantics is still hidden.
+    await tester.pump();
+    expect(tester.getSemantics(find.text('Text 6', skipOffstage: false)), matchesSemantics(isHidden: true));
+
+    handle.dispose();
+  });
+
   testWidgets('didFinishLayout has correct indices', (WidgetTester tester) async {
     final TestSliverChildListDelegate delegate = TestSliverChildListDelegate(
       List<Widget>.generate(