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add shorthands for scroll physics subclasses in framework (#193082) · suryaKommana2662/flutter@2710ade · GitHub
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add shorthands for scroll physics subclasses in framework (flutter#193082)
This PR adds dot shorthands via redirecting factories for `ScrollPhysics`, so you can do ```dart ListView.builder( physics: const .alwaysScrollable(), ) ``` I did not add one for `CarouselPhysics`, since that belongs in material_ui, which prevents adding a shorthand for it. Fixes flutter#192989 *If you had to change anything in the [flutter/tests] repo, include a link to the migration guide as per the [breaking change policy].* ## Pre-launch Checklist - [x] I read the [Contributor Guide] and followed the process outlined there for submitting PRs. - [x] I read the [AI contribution guidelines] and understand my responsibilities, or I am not using AI tools. - [x] I read the [Tree Hygiene] wiki page, which explains my responsibilities. - [x] I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement]. - [x] I signed the [CLA]. - [x] I listed at least one issue that this PR fixes in the description above. - [x] I updated/added relevant in-code documentation (doc comments with `///`). - [x] If this PR introduces a new feature or capability, I created and linked a website documentation issue or PR in [flutter/website] (or verified none is needed). - [x] I added new tests to check the change I am making, or this PR is [test-exempt]. - [x] I followed the [breaking change policy] and added [Data Driven Fixes] where supported. - [x] All existing and new tests are passing. If you need help, consider asking for advice on the #hackers-new channel on [Discord]. If this change needs to override an active code freeze, provide a comment explaining why. The code freeze workflow can be overridden by code reviewers. See pinned issues for any active code freezes with guidance. **Note**: The Flutter team is currently trialing the use of [Gemini Code Assist for GitHub](https://developers.google.com/gemini-code-assist/docs/review-github-code). Comments from the `gemini-code-assist` bot should not be taken as authoritative feedback from the Flutter team. If you find its comments useful you can update your code accordingly, but if you are unsure or disagree with the feedback, please feel free to wait for a Flutter team member's review for guidance on which automated comments should be addressed. <!-- Links --> [Contributor Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview [AI contribution guidelines]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#ai-contribution-guidelines [Tree Hygiene]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md [test-exempt]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests [Flutter Style Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md [Features we expect every widget to implement]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement [CLA]: https://cla.developers.google.com/ [flutter/tests]: https://github.com/flutter/tests [flutter/website]: https://github.com/flutter/website [breaking change policy]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes [Discord]: https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md [Data Driven Fixes]: https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md
1 parent 44f6c5e commit 2710ade

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Lines changed: 124 additions & 6 deletions

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‎packages/flutter/lib/src/widgets/scroll_physics.dart‎

Lines changed: 30 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -89,6 +89,29 @@ class ScrollPhysics {
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/// Creates an object with the default scroll physics.
9090
const ScrollPhysics({this.parent});
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92+
/// Creates an [AlwaysScrollableScrollPhysics] instance.
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const factory ScrollPhysics.alwaysScrollable({ScrollPhysics? parent}) =
94+
AlwaysScrollableScrollPhysics;
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96+
/// Creates a [BouncingScrollPhysics] instance.
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///
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/// The [decelerationRate] defaults to [ScrollDecelerationRate.normal].
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const factory ScrollPhysics.bouncing({
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ScrollPhysics? parent,
101+
ScrollDecelerationRate decelerationRate,
102+
}) = BouncingScrollPhysics;
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104+
/// Creates a [ClampingScrollPhysics] instance.
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const factory ScrollPhysics.clamping({ScrollPhysics? parent}) = ClampingScrollPhysics;
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107+
/// Creates a [NeverScrollableScrollPhysics] instance.
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const factory ScrollPhysics.neverScrollable({ScrollPhysics? parent}) =
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NeverScrollableScrollPhysics;
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/// Creates a [RangeMaintainingScrollPhysics] instance.
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const factory ScrollPhysics.rangeMaintaining({ScrollPhysics? parent}) =
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RangeMaintainingScrollPhysics;
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92115
/// If non-null, determines the default behavior for each method.
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///
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/// If a subclass of [ScrollPhysics] does not override a method, that subclass
@@ -612,6 +635,7 @@ class ScrollPhysics {
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/// if any, and then clamped to the new range.
613636
class RangeMaintainingScrollPhysics extends ScrollPhysics {
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/// Creates scroll physics that maintain the scroll position in range.
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// Any parameters that are added here should also be forwarded by `ScrollPhysics.rangeMaintaining`.
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const RangeMaintainingScrollPhysics({super.parent});
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@override
@@ -723,6 +747,9 @@ class RangeMaintainingScrollPhysics extends ScrollPhysics {
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/// of different types to get the desired scroll physics.
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class BouncingScrollPhysics extends ScrollPhysics {
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/// Creates scroll physics that bounce back from the edge.
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///
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/// The [decelerationRate] defaults to [ScrollDecelerationRate.normal].
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// Any parameters that are added here should also be forwarded by `ScrollPhysics.bouncing`.
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const BouncingScrollPhysics({
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this.decelerationRate = ScrollDecelerationRate.normal,
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super.parent,
@@ -937,6 +964,7 @@ class BouncingScrollPhysics extends ScrollPhysics {
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class ClampingScrollPhysics extends ScrollPhysics {
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/// Creates scroll physics that prevent the scroll offset from exceeding the
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/// bounds of the content.
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// Any parameters that are added here should also be forwarded by `ScrollPhysics.clamping`.
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const ClampingScrollPhysics({super.parent});
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942970
@override
@@ -1046,6 +1074,7 @@ class ClampingScrollPhysics extends ScrollPhysics {
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/// found on Android.
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class AlwaysScrollableScrollPhysics extends ScrollPhysics {
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/// Creates scroll physics that always lets the user scroll.
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// Any parameters that are added here should also be forwarded by `ScrollPhysics.alwaysScrollable`.
10491078
const AlwaysScrollableScrollPhysics({super.parent});
10501079

10511080
@override
@@ -1069,6 +1098,7 @@ class AlwaysScrollableScrollPhysics extends ScrollPhysics {
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/// found on Android.
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class NeverScrollableScrollPhysics extends ScrollPhysics {
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/// Creates scroll physics that does not let the user scroll.
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// Any parameters that are added here should also be forwarded by `ScrollPhysics.neverScrollable`.
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const NeverScrollableScrollPhysics({super.parent});
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10741104
@override

‎packages/flutter/test/widgets/scroll_physics_test.dart‎

Lines changed: 94 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -497,17 +497,25 @@ FlutterError
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ScrollableState scrollable = tester.state<ScrollableState>(find.byType(Scrollable));
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final ScrollPosition firstPosition = scrollable.position;
499499
expect(
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(firstPosition.physics as BouncingScrollPhysics).decelerationRate,
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ScrollDecelerationRate.normal,
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firstPosition.physics,
501+
isA<BouncingScrollPhysics>().having(
502+
(BouncingScrollPhysics bouncingPhysics) => bouncingPhysics.decelerationRate,
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'decelerationRate',
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ScrollDecelerationRate.normal,
505+
),
502506
);
503507

504508
// Identical configuration should not recreate ScrollPosition.
505509
await tester.pumpWidget(buildScrollable());
506510
scrollable = tester.state<ScrollableState>(find.byType(Scrollable));
507511
expect(scrollable.position, same(firstPosition));
508512
expect(
509-
(scrollable.position.physics as BouncingScrollPhysics).decelerationRate,
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ScrollDecelerationRate.normal,
513+
scrollable.position.physics,
514+
isA<BouncingScrollPhysics>().having(
515+
(BouncingScrollPhysics bouncingPhysics) => bouncingPhysics.decelerationRate,
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'decelerationRate',
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ScrollDecelerationRate.normal,
518+
),
511519
);
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513521
// Different decelerationRate should recreate ScrollPosition.
@@ -518,8 +526,12 @@ FlutterError
518526
final ScrollPosition secondPosition = scrollable.position;
519527
expect(secondPosition, isNot(same(firstPosition)));
520528
expect(
521-
(secondPosition.physics as BouncingScrollPhysics).decelerationRate,
522-
ScrollDecelerationRate.fast,
529+
secondPosition.physics,
530+
isA<BouncingScrollPhysics>().having(
531+
(BouncingScrollPhysics bouncingPhysics) => bouncingPhysics.decelerationRate,
532+
'decelerationRate',
533+
ScrollDecelerationRate.fast,
534+
),
523535
);
524536
});
525537

@@ -577,6 +589,82 @@ FlutterError
577589
expect(identical(physicsB1, physicsC2), isTrue);
578590
expect(physicsB1.shouldUpdate(physicsC2), isFalse);
579591
});
592+
593+
test('ScrollPhysics supports shorthands for AlwaysScrollableScrollPhysics', () {
594+
ScrollPhysics physics = const .alwaysScrollable();
595+
596+
expect(physics, isA<AlwaysScrollableScrollPhysics>());
597+
expect(physics.parent, isNull);
598+
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physics = const .alwaysScrollable(parent: ClampingScrollPhysics());
600+
601+
expect(physics, isA<AlwaysScrollableScrollPhysics>());
602+
expect(physics.parent, isA<ClampingScrollPhysics>());
603+
});
604+
605+
test('ScrollPhysics supports shorthands for BouncingScrollPhysics', () {
606+
const ScrollPhysics physics = .bouncing();
607+
608+
expect(physics.parent, isNull);
609+
expect(
610+
physics,
611+
isA<BouncingScrollPhysics>().having(
612+
(BouncingScrollPhysics bouncingPhysics) => bouncingPhysics.decelerationRate,
613+
'decelerationRate',
614+
ScrollDecelerationRate.normal,
615+
),
616+
);
617+
618+
const ScrollPhysics physics2 = .bouncing(
619+
parent: ClampingScrollPhysics(),
620+
decelerationRate: ScrollDecelerationRate.fast,
621+
);
622+
expect(
623+
physics2,
624+
isA<BouncingScrollPhysics>().having(
625+
(BouncingScrollPhysics bouncingPhysics) => bouncingPhysics.decelerationRate,
626+
'decelerationRate',
627+
ScrollDecelerationRate.fast,
628+
),
629+
);
630+
expect(physics2.parent, isA<ClampingScrollPhysics>());
631+
});
632+
633+
test('ScrollPhysics supports shorthands for ClampingScrollPhysics', () {
634+
ScrollPhysics physics = const .clamping();
635+
636+
expect(physics, isA<ClampingScrollPhysics>());
637+
expect(physics.parent, isNull);
638+
639+
physics = const .clamping(parent: AlwaysScrollableScrollPhysics());
640+
641+
expect(physics, isA<ClampingScrollPhysics>());
642+
expect(physics.parent, isA<AlwaysScrollableScrollPhysics>());
643+
});
644+
645+
test('ScrollPhysics supports shorthands for NeverScrollableScrollPhysics', () {
646+
ScrollPhysics physics = const .neverScrollable();
647+
648+
expect(physics, isA<NeverScrollableScrollPhysics>());
649+
expect(physics.parent, isNull);
650+
651+
physics = const .neverScrollable(parent: ClampingScrollPhysics());
652+
653+
expect(physics, isA<NeverScrollableScrollPhysics>());
654+
expect(physics.parent, isA<ClampingScrollPhysics>());
655+
});
656+
657+
test('ScrollPhysics supports shorthands for RangeMaintainingScrollPhysics', () {
658+
ScrollPhysics physics = const .rangeMaintaining();
659+
660+
expect(physics, isA<RangeMaintainingScrollPhysics>());
661+
expect(physics.parent, isNull);
662+
663+
physics = const .rangeMaintaining(parent: ClampingScrollPhysics());
664+
665+
expect(physics, isA<RangeMaintainingScrollPhysics>());
666+
expect(physics.parent, isA<ClampingScrollPhysics>());
667+
});
580668
}
581669

582670
class ReactiveScrollPhysics extends ScrollPhysics {

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