respect reversed scroll views (#39195)
This PR makes Scrollable scroll in correct direction when reverse: true on desktop and web
diff --git a/packages/flutter/lib/src/widgets/scrollable.dart b/packages/flutter/lib/src/widgets/scrollable.dart
index e6b9567..f3e9ebb 100644
--- a/packages/flutter/lib/src/widgets/scrollable.dart
+++ b/packages/flutter/lib/src/widgets/scrollable.dart
@@ -9,6 +9,7 @@
import 'package:flutter/gestures.dart';
import 'package:flutter/rendering.dart';
import 'package:flutter/scheduler.dart';
+import 'package:flutter/painting.dart';
import 'basic.dart';
import 'framework.dart';
@@ -528,9 +529,14 @@
// Returns the offset that should result from applying [event] to the current
// position, taking min/max scroll extent into account.
double _targetScrollOffsetForPointerScroll(PointerScrollEvent event) {
- final double delta = widget.axis == Axis.horizontal
+ double delta = widget.axis == Axis.horizontal
? event.scrollDelta.dx
: event.scrollDelta.dy;
+
+ if (axisDirectionIsReversed(widget.axisDirection)) {
+ delta *= -1;
+ }
+
return math.min(math.max(position.pixels + delta, position.minScrollExtent),
position.maxScrollExtent);
}
diff --git a/packages/flutter/test/widgets/scrollable_test.dart b/packages/flutter/test/widgets/scrollable_test.dart
index ac14564..b9a3183 100644
--- a/packages/flutter/test/widgets/scrollable_test.dart
+++ b/packages/flutter/test/widgets/scrollable_test.dart
@@ -8,12 +8,18 @@
import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';
-Future<void> pumpTest(WidgetTester tester, TargetPlatform platform, {bool scrollable = true}) async {
+Future<void> pumpTest(
+ WidgetTester tester,
+ TargetPlatform platform, {
+ bool scrollable = true,
+ bool reverse = false,
+}) async {
await tester.pumpWidget(MaterialApp(
theme: ThemeData(
platform: platform,
),
home: CustomScrollView(
+ reverse: reverse,
physics: scrollable ? null : const NeverScrollableScrollPhysics(),
slivers: const <Widget>[
SliverToBoxAdapter(child: SizedBox(height: 2000.0)),
@@ -248,4 +254,17 @@
await tester.sendEventToBinding(testPointer.scroll(const Offset(0.0, 20.0)), result);
expect(getScrollOffset(tester), 0.0);
});
+
+ testWidgets('Scrolls in correct direction when scroll axis is reversed', (WidgetTester tester) async {
+ await pumpTest(tester, TargetPlatform.fuchsia, reverse: true);
+
+ final Offset scrollEventLocation = tester.getCenter(find.byType(Viewport));
+ final TestPointer testPointer = TestPointer(1, ui.PointerDeviceKind.mouse);
+ // Create a hover event so that |testPointer| has a location when generating the scroll.
+ testPointer.hover(scrollEventLocation);
+ final HitTestResult result = tester.hitTestOnBinding(scrollEventLocation);
+ await tester.sendEventToBinding(testPointer.scroll(const Offset(0.0, -20.0)), result);
+
+ expect(getScrollOffset(tester), 20.0);
+ });
}
