Fix precision error in RenderSliverFixedExtentBoxAdaptor assertion (#95598)

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

@@ -68,7 +68,7 @@ abstract class RenderSliverFixedExtentBoxAdaptor extends RenderSliverMultiBoxAda
     if (itemExtent > 0.0) {
       final double actual = scrollOffset / itemExtent;
       final int round = actual.round();
-      if ((actual - round).abs() < precisionErrorTolerance) {
+      if ((actual * itemExtent - round * itemExtent).abs() < precisionErrorTolerance) {
         return round;
       }
       return actual.floor();
@@ -88,7 +88,7 @@ abstract class RenderSliverFixedExtentBoxAdaptor extends RenderSliverMultiBoxAda
     if (itemExtent > 0.0) {
       final double actual = scrollOffset / itemExtent - 1;
       final int round = actual.round();
-      if (_isWithinPrecisionErrorTolerance(actual, round)) {
+      if ((actual * itemExtent - round * itemExtent).abs() < precisionErrorTolerance) {
         return math.max(0, round);
       }
       return math.max(0, actual.ceil());
@@ -358,7 +358,3 @@ class RenderSliverFixedExtentList extends RenderSliverFixedExtentBoxAdaptor {
     markNeedsLayout();
   }
 }
-
-bool _isWithinPrecisionErrorTolerance(double actual, int round) {
-  return (actual - round).abs() < precisionErrorTolerance;
-}

packages/flutter/test/rendering/sliver_fixed_extent_layout_test.dart

@@ -45,8 +45,8 @@ void main() {
     // Regression test for https://github.com/flutter/flutter/issues/68182
 
     const double genericItemExtent = 600.0;
-    const double extraValueToNotHaveRoundingIssues = 0.0000001; // 6 zeros
-    const double extraValueToHaveRoundingIssues = 0.00000001; // 7 zeros
+    const double extraValueToNotHaveRoundingIssues = 1e-10;
+    const double extraValueToHaveRoundingIssues = 1e-11;
 
     test('should be 0 when item extent is 0', () {
       const double offsetValueWhichDoesntCare = 1234;
@@ -91,7 +91,7 @@ void main() {
       expect(actual, 5);
     });
 
-    test('should be 5 when offset is 6 times greater than a specific item extent where the division will return more than 13 zero decimals', () {
+    test('should be 5 when offset is 6 times greater than a specific item extent where the division will return more than 13 zero decimals', () {
       const double itemExtentSpecificForAProblematicScreenSize = 411.42857142857144;
       final int actual = testGetMaxChildIndexForScrollOffset(
         itemExtentSpecificForAProblematicScreenSize * 6 + extraValueToHaveRoundingIssues,
@@ -100,7 +100,7 @@ void main() {
       expect(actual, 5);
     });
 
-    test('should be 0 when offset is 0.00000001 times greater than item extent where the division will return more than 13 zero decimals', () {
+    test('should be 0 when offset is a bit greater than item extent', () {
       final int actual = testGetMaxChildIndexForScrollOffset(
         genericItemExtent + extraValueToHaveRoundingIssues,
         genericItemExtent,

packages/flutter/test/widgets/page_view_test.dart

@@ -1096,4 +1096,31 @@ void main() {
 
     expect(tester.widget<SliverFillViewport>(viewportFinder()).padEnds, false);
   });
+
+  testWidgets('PageView - precision error inside RenderSliverFixedExtentBoxAdaptor', (WidgetTester tester) async {
+    // Regression test for https://github.com/flutter/flutter/issues/95101
+
+    final PageController controller = PageController(initialPage: 152);
+    await tester.pumpWidget(
+      Center(
+        child: SizedBox(
+          width: 392.72727272727275,
+          child: Directionality(
+            textDirection: TextDirection.ltr,
+            child: PageView.builder(
+              controller: controller,
+              itemCount: 366,
+              itemBuilder: (BuildContext context, int index) {
+                return const SizedBox();
+              },
+            ),
+          ),
+        ),
+      ),
+    );
+
+    controller.jumpToPage(365);
+    await tester.pump();
+    expect(tester.takeException(), isNull);
+  });
 }