Add macOS-specific scroll physics #108298

moffatman · 2022-07-25T15:29:42Z

Dotted line = BouncingScrollPhysics
Solid line = new BouncingDesktopScrollPhysics
X-marks = Recorded data

Fixes #107752

Pre-launch Checklist

I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
I read the [Tree Hygiene] wiki page, which explains my responsibilities.
I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement].
I signed the [CLA].
I listed at least one issue that this PR fixes in the description above.
I updated/added relevant documentation (doc comments with ///).
I added new tests to check the change I am making, or this PR is [test-exempt].
All existing and new tests are passing.

hellohuanlin · 2022-08-01T18:18:37Z

im having trouble understanding this graph. is y-axis the initial distance or initial speed?

moffatman · 2022-08-02T13:25:38Z

im having trouble understanding this graph. is y-axis the initial distance or initial speed?

The y-axis is velocity

Piinks · 2022-08-09T19:27:53Z

Thanks so much for this @moffatman! And apologies for the delay, I should be finished reviewing today

Piinks

You want to update the getScrollPhysics of CupertinoScrollBehavior as well. 👍

Piinks · 2022-08-09T19:31:20Z

packages/flutter/lib/src/gestures/velocity_tracker.dart

+///
+/// To obtain a velocity, call [getVelocity] or [getVelocityEstimate]. The
+/// estimated velocity is typically used as the initial flinging velocity of a
+/// `Scrollable`, when its drag gesture ends.


In the docs for the iOS version, there is a reference to https://developer.apple.com/documentation/uikit/uiscrollviewdelegate/1619385-scrollviewwillenddragging, is that also relevant here? Or is there another, more relevant reference?

There isn't a direct analogue, in AppKit the scroll momentum state is seen based on the incoming events' [NSEvent momentumPhase]. The part which converts the velocity to the momentum is not exposed at all.

packages/flutter/lib/src/physics/friction_simulation.dart

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

packages/flutter/test/cupertino/picker_test.dart

packages/flutter/test/material/refresh_indicator_test.dart

packages/flutter/test/widgets/nested_scroll_view_test.dart

packages/flutter/test/widgets/scrollable_fling_test.dart

packages/flutter/test/widgets/scrollable_test.dart

packages/flutter/test/widgets/page_view_test.dart

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

Piinks

This is looking really good. Apologies for the delay while I was gone.

packages/flutter/lib/src/gestures/velocity_tracker.dart

Piinks · 2022-09-14T20:51:05Z

packages/flutter/lib/src/physics/friction_simulation.dart

+  double g = guess;
+  for (int i = 0; i < iterations; i++) {
+    g = g - (f(g) - target) / df(g);
+  }
+  return g;


The style guide discourages abbreviations https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo#avoid-abbreviations

Can you expand this shorthand so it is easier to understand?

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

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

Piinks

This is really great, thank you for your incredible attention to detail. :)
LGTM!

appinteractive · 2022-12-21T21:22:49Z

which flutter version will this land in?

moffatman · 2022-12-21T21:48:21Z

@appinteractive Has been in beta channel for a while, should be in the next stable version 3.7. No idea when that releases though

hellohuanlin · 2022-12-21T22:31:54Z

IIRC next release will be around next Jan @appinteractive

appinteractive · 2022-12-22T12:47:47Z

Thanks for the response, tried it in 3.7 pre but I still have scroll that has way to little friction on macOS, do I need to specify anything for it to work? Using MaterialApp as a base because Cupertino is barely usable with plugins. (Missing Material)

moffatman · 2022-12-22T14:56:25Z

@appinteractive Can you share some code which reproduces the issue? If you are setting custom scroll physics on any widget, the correct physics for macOS should be BouncingScrollPhysics(decelerationRate: ScrollDecelerationRate.fast). But if you never set physics on any widget, it should be getting the correct physics by default.

GroovinChip · 2023-01-27T07:56:51Z

@Piinks After the release of Flutter 3.7 with this included, I'm seeing The Scrollbar's ScrollController has no ScrollPosition attached. errors for apps using macos_ui. I assume I need to remove or alter some of the custom scrolling code in the library, but my efforts so far haven't yielded any results. I read the desktop scrolling migration guide and I am only more confused. Should I remove all usages of our custom MacosScrollbar, as well as our custom MacosScrollBehavior?

EDIT: It's also worth mentioning that the errors I'm getting do not trace which scrollable the issue is arising from :/

Piinks · 2023-01-27T09:43:13Z

Hi @GroovinChip, it sounds like there may be a regression. Can you please file an issue with the last flutter version you were using and a minimal reproduction?
We won’t be able to diagnose a potential regression in an old PR.

GroovinChip · 2023-01-27T09:51:59Z

@Piinks Sure thing! Didn't realize it could be a regression :)

GroovinChip · 2023-01-27T10:14:10Z

Hi @GroovinChip, it sounds like there may be a regression. Can you please file an issue with the last flutter version you were using and a minimal reproduction? We won’t be able to diagnose a potential regression in an old PR.

Done - #119323

flutter-dashboard bot added f: gestures flutter/packages/flutter/gestures repository. f: scrolling Viewports, list views, slivers, etc. framework flutter/packages/flutter repository. See also f: labels. labels Jul 25, 2022

moffatman force-pushed the macos_physics branch from 0527ad0 to 662fddf Compare July 25, 2022 21:12

goderbauer requested a review from Piinks July 26, 2022 22:13

tomgilder mentioned this pull request Jul 29, 2022

Web: scrolling behaviour on Mac does not match platform #75850

Closed

moffatman mentioned this pull request Jul 30, 2022

Scroll inertia cancel for iPadOS flutter/engine#34929

Merged

8 tasks

Piinks added platform-mac Building on or for macOS specifically a: desktop Running on desktop a: fidelity Matching the OEM platforms better labels Aug 1, 2022

Piinks reviewed Aug 9, 2022

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moffatman force-pushed the macos_physics branch from 662fddf to 63529d1 Compare August 23, 2022 05:52

goderbauer requested a review from Piinks August 23, 2022 22:09

Piinks reviewed Sep 14, 2022

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moffatman added 4 commits September 15, 2022 01:28

Add macOS-specific scroll physics

d5db5ea

Fix tests

c168865

Refactor, scope tests

b842ad9

Address feedback

e4c60d1

moffatman force-pushed the macos_physics branch from 63529d1 to e4c60d1 Compare September 15, 2022 05:29

Clarify ScrollDecelerationRate enum

125907b

Piinks approved these changes Sep 19, 2022

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Piinks added the autosubmit Merge PR when tree becomes green via auto submit App label Sep 19, 2022

auto-submit bot merged commit 70b19ff into flutter:master Sep 19, 2022

This was referenced Sep 20, 2022

Roll Flutter from 99475b1b0bee to b55bbb7bffc7 (36 revisions) flutter/packages#2624

Merged

Roll Flutter from 99475b1b0bee to b55bbb7bffc7 (36 revisions) flutter/plugins#6456

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engine-flutter-autoroll added a commit to engine-flutter-autoroll/packages that referenced this pull request Sep 20, 2022

70b19ff98 Add macOS-specific scroll physics (flutter/flutter#108298)

19abad2

engine-flutter-autoroll added a commit to engine-flutter-autoroll/plugins that referenced this pull request Sep 20, 2022

70b19ff Add macOS-specific scroll physics (flutter/flutter#108298)

7970f84

moffatman mentioned this pull request Nov 21, 2022

BouncingScrollPhysics should propagate decelerationRate #115797

Merged

8 tasks

GroovinChip mentioned this pull request Jan 27, 2023

Potential regression of #108298 after Flutter 3.7.0 upgrade #119323

Closed

xu-baolin mentioned this pull request Feb 7, 2023

[Desktop] RefreshIndicator can not be dragged to its full extent #119702

Closed

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Add macOS-specific scroll physics #108298

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Add macOS-specific scroll physics #108298

Add macOS-specific scroll physics #108298

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moffatman commented Jul 25, 2022

Pre-launch Checklist

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