From 13fe079bb3ddeebded7253f312ba7cc4c81feafc Mon Sep 17 00:00:00 2001
From: chunhtai <47866232+chunhtai@users.noreply.github.com>
Date: Mon, 1 Feb 2021 12:46:05 -0800
Subject: [PATCH] fixes preceision error during SliverGridRegularTileLayout
 (#74851)

---
 .../lib/src/rendering/sliver_grid.dart        |  2 +-
 .../flutter/test/widgets/grid_view_test.dart  | 24 +++++++++++++++++++
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/packages/flutter/lib/src/rendering/sliver_grid.dart b/packages/flutter/lib/src/rendering/sliver_grid.dart
index c38a41e385e..e73587faabd 100644
--- a/packages/flutter/lib/src/rendering/sliver_grid.dart
+++ b/packages/flutter/lib/src/rendering/sliver_grid.dart
@@ -194,7 +194,7 @@ class SliverGridRegularTileLayout extends SliverGridLayout {
 
   @override
   int getMinChildIndexForScrollOffset(double scrollOffset) {
-    return mainAxisStride > 0.0 ? crossAxisCount * (scrollOffset ~/ mainAxisStride) : 0;
+    return mainAxisStride > precisionErrorTolerance ? crossAxisCount * (scrollOffset ~/ mainAxisStride) : 0;
   }
 
   @override
diff --git a/packages/flutter/test/widgets/grid_view_test.dart b/packages/flutter/test/widgets/grid_view_test.dart
index 276e4da80ec..4376e1a7485 100644
--- a/packages/flutter/test/widgets/grid_view_test.dart
+++ b/packages/flutter/test/widgets/grid_view_test.dart
@@ -315,6 +315,30 @@ void main() {
     expect(find.text('4'), findsNothing);
   });
 
+  testWidgets('SliverGridRegularTileLayout - can handle close to zero mainAxisStride', (WidgetTester tester) async {
+    const SliverGridDelegateWithMaxCrossAxisExtent delegate = SliverGridDelegateWithMaxCrossAxisExtent(
+      childAspectRatio: 1e300,
+      maxCrossAxisExtent: 500.0,
+    );
+    final SliverGridLayout layout = delegate.getLayout(
+      const SliverConstraints(
+        axisDirection: AxisDirection.down,
+        growthDirection: GrowthDirection.forward,
+        userScrollDirection: ScrollDirection.forward,
+        scrollOffset: 100.0,
+        precedingScrollExtent: 0.0,
+        overlap: 0.0,
+        remainingPaintExtent: 0.0,
+        crossAxisExtent: 500,
+        crossAxisDirection: AxisDirection.right,
+        viewportMainAxisExtent: 100.0,
+        remainingCacheExtent: 0.0,
+        cacheOrigin: 0.0,
+      )
+    );
+    expect(layout.getMinChildIndexForScrollOffset(1000.0), 0.0);
+  });
+
   testWidgets('GridView - change maxChildCrossAxisExtent', (WidgetTester tester) async {
     final List<int> log = <int>[];