Revert "update ScrollMetricsNotification (#87421)" (#87693)
This reverts commit 52bf9dbbd72ecc787474da223c32d2368a4ad49e.
diff --git a/packages/flutter/lib/src/widgets/scroll_position.dart b/packages/flutter/lib/src/widgets/scroll_position.dart
index 60e78b3..a227263 100644
--- a/packages/flutter/lib/src/widgets/scroll_position.dart
+++ b/packages/flutter/lib/src/widgets/scroll_position.dart
@@ -558,7 +558,7 @@
// It isn't safe to trigger the ScrollMetricsNotification if we are in
// the middle of rendering the frame, the developer is likely to schedule
// a new frame(build scheduled during frame is illegal).
- if (!_haveScheduledUpdateNotification) {
+ if (_lastMetrics != null && !_haveScheduledUpdateNotification) {
scheduleMicrotask(didUpdateScrollMetrics);
_haveScheduledUpdateNotification = true;
}
diff --git a/packages/flutter/lib/src/widgets/scrollbar.dart b/packages/flutter/lib/src/widgets/scrollbar.dart
index c91089f..b23d687 100644
--- a/packages/flutter/lib/src/widgets/scrollbar.dart
+++ b/packages/flutter/lib/src/widgets/scrollbar.dart
@@ -1224,16 +1224,25 @@
@override
void didChangeDependencies() {
super.didChangeDependencies();
- assert(_debugScheduleCheckHasValidScrollPosition());
+ _maybeTriggerScrollbar();
}
- bool _debugScheduleCheckHasValidScrollPosition() {
- if (!showScrollbar)
- return true;
+ // Waits one frame and cause an empty scroll event (zero delta pixels).
+ //
+ // This allows the thumb to show immediately when isAlwaysShown is true.
+ // A scroll event is required in order to paint the thumb.
+ void _maybeTriggerScrollbar() {
WidgetsBinding.instance!.addPostFrameCallback((Duration duration) {
- assert(_debugCheckHasValidScrollPosition());
+ final ScrollController? scrollController = widget.controller ?? PrimaryScrollController.of(context);
+ if (showScrollbar) {
+ _fadeoutTimer?.cancel();
+ // Wait one frame and cause an empty scroll event. This allows the
+ // thumb to show immediately when isAlwaysShown is true. A scroll
+ // event is required in order to paint the thumb.
+ assert(_debugCheckHasValidScrollPosition());
+ scrollController!.position.didUpdateScrollPositionBy(0);
+ }
});
- return true;
}
void _validateInteractions(AnimationStatus status) {
@@ -1356,8 +1365,7 @@
super.didUpdateWidget(oldWidget);
if (widget.isAlwaysShown != oldWidget.isAlwaysShown) {
if (widget.isAlwaysShown == true) {
- assert(_debugScheduleCheckHasValidScrollPosition());
- _fadeoutTimer?.cancel();
+ _maybeTriggerScrollbar();
_fadeoutAnimationController.animateTo(1.0);
} else {
_fadeoutAnimationController.reverse();
diff --git a/packages/flutter/test/cupertino/scrollbar_test.dart b/packages/flutter/test/cupertino/scrollbar_test.dart
index 0359f11..bbdfa21 100644
--- a/packages/flutter/test/cupertino/scrollbar_test.dart
+++ b/packages/flutter/test/cupertino/scrollbar_test.dart
@@ -5,7 +5,6 @@
import 'dart:ui' as ui;
import 'package:flutter/cupertino.dart';
-import 'package:flutter/foundation.dart';
import 'package:flutter/services.dart';
import 'package:flutter_test/flutter_test.dart';
@@ -390,16 +389,9 @@
);
}
- final FlutterExceptionHandler? handler = FlutterError.onError;
- FlutterErrorDetails? error;
- FlutterError.onError = (FlutterErrorDetails details) {
- error = details;
- };
-
await tester.pumpWidget(viewWithScroll());
- expect(error, isNotNull);
-
- FlutterError.onError = handler;
+ final AssertionError exception = tester.takeException() as AssertionError;
+ expect(exception, isAssertionError);
},
);
diff --git a/packages/flutter/test/widgets/scroll_notification_test.dart b/packages/flutter/test/widgets/scroll_notification_test.dart
index e56b4cd..1f9d512 100644
--- a/packages/flutter/test/widgets/scroll_notification_test.dart
+++ b/packages/flutter/test/widgets/scroll_notification_test.dart
@@ -21,9 +21,8 @@
);
}
await tester.pumpWidget(buildFrame(1200.0));
- expect(events.length, 1);
+ expect(events.length, 0);
- events.clear();
await tester.pumpWidget(buildFrame(1000.0));
// Change the content dimensions will trigger a new event.
expect(events.length, 1);
diff --git a/packages/flutter/test/widgets/scrollbar_test.dart b/packages/flutter/test/widgets/scrollbar_test.dart
index c055842..4008057 100644
--- a/packages/flutter/test/widgets/scrollbar_test.dart
+++ b/packages/flutter/test/widgets/scrollbar_test.dart
@@ -4,7 +4,6 @@
import 'dart:ui' as ui;
-import 'package:flutter/foundation.dart';
import 'package:flutter/src/physics/utils.dart' show nearEqual;
import 'package:flutter/widgets.dart';
import 'package:flutter_test/flutter_test.dart';
@@ -1144,12 +1143,6 @@
});
testWidgets('RawScrollbar.isAlwaysShown asserts that a ScrollPosition is attached', (WidgetTester tester) async {
- final FlutterExceptionHandler? handler = FlutterError.onError;
- FlutterErrorDetails? error;
- FlutterError.onError = (FlutterErrorDetails details) {
- error = details;
- };
-
await tester.pumpWidget(
Directionality(
textDirection: TextDirection.ltr,
@@ -1170,15 +1163,12 @@
),
);
await tester.pumpAndSettle();
-
- expect(error, isNotNull);
- final AssertionError exception = error!.exception as AssertionError;
+ final AssertionError exception = tester.takeException() as AssertionError;
+ expect(exception, isAssertionError);
expect(
exception.message,
contains("The Scrollbar's ScrollController has no ScrollPosition attached."),
);
-
- FlutterError.onError = handler;
});
testWidgets('Interactive scrollbars should have a valid scroll controller', (WidgetTester tester) async {
