[cupertino_ui] Dim disabled CupertinoSlider controls by Wreos · Pull Request #13419 · flutter/packages

Wreos · 2026-10-25T11:14:08Z

Dims CupertinoSlider to 50% opacity when onChanged is null, matching the disabled appearance in native UIKit Slider component on iOS. Adds light/dark regression tests for disabling and re-enabling the slider.

Fixes flutter/flutter#106691.

Screenshots

Flutter before/after: iPhone 16 Pro simulator, iOS 18.6, light mode, value 0.67. The top slider is enabled; the bottom is disabled. The native reference shows stock UISlider controls in both themes.

Before	After	Native UIKit reference

Also checked native UIKit on iOS 26.5, where the disabled visual element uses 0.5 opacity. This fixes disabled styling, not the slider's overall design.

Validation: all 23 tests in test/slider_test.dart pass; targeted analysis and formatting pass. The full package suite has not been run locally. No public API changes.

Pre-Review Checklist

If you need help, consider asking for advice on the #hackers-new channel on Discord.

Note: The Flutter team is currently trialing the use of Gemini Code Assist for GitHub. 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.

Regular contributors who have demonstrated familiarity with the repository guidelines only need to comment if the PR is not auto-exempted by repo tooling. ↩ ↩²

gemini-code-assist

Code Review

This pull request updates CupertinoSlider to dim when disabled by wrapping it in an Opacity widget, matching the native iOS appearance. It also adds tests to verify the visual and functional behavior of the disabled slider and updates existing semantics tests. The review feedback suggests conditionally applying the Opacity widget only when the slider is disabled to avoid unnecessary widget tree overhead, and updating the tests to assert the absence of the Opacity widget when the slider is enabled.

gemini-code-assist · 2026-10-25T11:22:48Z

+    return Opacity(
+      opacity: widget.onChanged == null ? _kDisabledOpacity : 1.0,
+      child: _CupertinoSliderRenderObjectWidget(
+        value: (widget.value - widget.min) / (widget.max - widget.min),
+        divisions: widget.divisions,
+        activeColor: CupertinoDynamicColor.resolve(
+          widget.activeColor ?? CupertinoTheme.of(context).primaryColor,
+          context,
+        ),
+        thumbColor: widget.thumbColor,
+        onChanged: widget.onChanged != null ? _handleChanged : null,
+        onChangeStart: widget.onChangeStart != null ? _handleDragStart : null,
+        onChangeEnd: widget.onChangeEnd != null ? _handleDragEnd : null,
+        vsync: this,
      ),
-      thumbColor: widget.thumbColor,
-      onChanged: widget.onChanged != null ? _handleChanged : null,
-      onChangeStart: widget.onChangeStart != null ? _handleDragStart : null,
-      onChangeEnd: widget.onChangeEnd != null ? _handleDragEnd : null,
-      vsync: this,
    );


Wrapping the slider in an Opacity widget when it is enabled (i.e., onChanged != null) introduces unnecessary overhead in the widget tree. In Flutter, it is a best practice to conditionally wrap widgets in Opacity only when the opacity is actually less than 1.0 (similar to how CupertinoButton handles disabledOpacity). This keeps the widget tree shallower and avoids any potential performance cost of the Opacity widget during normal enabled use.

final Widget result = _CupertinoSliderRenderObjectWidget( value: (widget.value - widget.min) / (widget.max - widget.min), divisions: widget.divisions, activeColor: CupertinoDynamicColor.resolve( widget.activeColor ?? CupertinoTheme.of(context).primaryColor, context, ), thumbColor: widget.thumbColor, onChanged: widget.onChanged != null ? _handleChanged : null, onChangeStart: widget.onChangeStart != null ? _handleDragStart : null, onChangeEnd: widget.onChangeEnd != null ? _handleDragEnd : null, vsync: this, ); if (widget.onChanged == null) { return Opacity( opacity: _kDisabledOpacity, child: result, ); } return result;

I think we should keep the wrapper here. Opacity at 1.0 already uses a fast path without an intermediate buffer. Adding and removing it would recreate the slider render object whenever enabled changes. Flutter also recommends keeping the subtree structure stable, and CupertinoSwitch uses the same approach.

I added checks in 4b4cde2 to verify that the render object stays the same after disabling and re-enabling, in both themes.

gemini-code-assist · 2026-10-25T11:22:48Z

+      final Finder opacity = find.descendant(
+        of: find.byType(CupertinoSlider),
+        matching: find.byType(Opacity),
+      );
+      expect(tester.widget<Opacity>(opacity).opacity, 1.0);
+      final Size enabledSize = tester.getSize(find.byType(CupertinoSlider));
+
+      updateState(() => enabled = false);
+      await tester.pump();
+      expect(tester.widget<Opacity>(opacity).opacity, 0.5);
+      expect(tester.getSize(find.byType(CupertinoSlider)), enabledSize);
+      final CupertinoSlider slider = tester.widget<CupertinoSlider>(find.byType(CupertinoSlider));
+      expect(slider.activeColor, CupertinoColors.systemPurple);
+      expect(slider.thumbColor, CupertinoColors.systemOrange);
+      await tester.dragFrom(tester.getCenter(find.byType(CupertinoSlider)), const Offset(50, 0));
+      expect(value, 0.5);
+
+      updateState(() => enabled = true);
+      await tester.pump();
+      expect(tester.widget<Opacity>(opacity).opacity, 1.0);
+      await tester.dragFrom(tester.getCenter(find.byType(CupertinoSlider)), const Offset(50, 0));
+      expect(value, greaterThan(0.5));


Since the Opacity widget is now conditionally applied only when the slider is disabled, update the tests to assert that no Opacity widget is present when the slider is enabled.

expect(find.byType(Opacity), findsNothing); final Size enabledSize = tester.getSize(find.byType(CupertinoSlider)); updateState(() => enabled = false); await tester.pump(); final Finder opacity = find.descendant( of: find.byType(CupertinoSlider), matching: find.byType(Opacity), ); expect(tester.widget<Opacity>(opacity).opacity, 0.5); expect(tester.getSize(find.byType(CupertinoSlider)), enabledSize); final CupertinoSlider slider = tester.widget<CupertinoSlider>(find.byType(CupertinoSlider)); expect(slider.activeColor, CupertinoColors.systemPurple); expect(slider.thumbColor, CupertinoColors.systemOrange); await tester.dragFrom(tester.getCenter(find.byType(CupertinoSlider)), const Offset(50, 0)); expect(value, 0.5); updateState(() => enabled = true); await tester.pump(); expect(find.byType(Opacity), findsNothing); await tester.dragFrom(tester.getCenter(find.byType(CupertinoSlider)), const Offset(50, 0)); expect(value, greaterThan(0.5));

This depends on the conditional-wrapper suggestion above, which I have not adopted. The tests continue checking opacity 1.0 / 0.5 / 1.0 and now also check that the slider render object is preserved across both transitions. Slider tests, targeted analysis, and formatting pass.

dkwingsmt

LGTM. Thank you for the fix (and the well-written description)!

…r#196450) flutter/packages@653628e...14f9933 2026-11-12 [email protected] [material_ui] Fix SnackBarThemeData.lerp dropping showCloseIcon (flutter/packages#13449) 2026-11-11 [email protected] [ci] Update repo for 3.50 stable release (flutter/packages#13628) 2026-11-11 [email protected] [vector_graphics] Use font-family lists as a family with fallbacks (flutter/packages#13552) 2026-11-11 [email protected] Roll Flutter (stable) from c197ca5 to ab29120 (1647 revisions) (flutter/packages#13625) 2026-11-11 [email protected] [shared_prferences] Adopts mockito-kotlin in tests (flutter/packages#13624) 2026-11-11 [email protected] [cupertino_ui] Dim disabled CupertinoSlider controls (flutter/packages#13419) 2026-11-11 [email protected] [flutter_svg] Invalidate pending cache entries on clear and evict (flutter/packages#13595) 2026-11-11 [email protected] [cupertino_ui] Fix the tinted button's fill opacity (flutter/packages#13436) 2026-11-11 [email protected] [various] Support SVG filters (blur, offset, feMerge) (flutter/packages#11909) If this roll has caused a breakage, revert this CL and set the roller to dry run mode using the controls here: https://autoroll.skia.org/r/flutter-packages-flutter-autoroll Please CC [email protected] on the revert to ensure that a human is aware of the problem. To file a bug in Flutter: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

[cupertino_ui] Dim disabled CupertinoSlider controls

f64f379

github-actions Bot added p: cupertino_ui triage-design Should be looked at in design triage labels Oct 25, 2026

Wreos marked this pull request as ready for review October 25, 2026 11:21

gemini-code-assist Bot reviewed Oct 25, 2026

View reviewed changes

[cupertino_ui] Verify slider render object survives enabled changes

4b4cde2

This was referenced Oct 28, 2026

CupertinoSlider with null onChanged doesn't display as disabled flutter/flutter#106691

Closed

Disabled widgets on iOS: no disabled look, or no "dimmed" for VoiceOver LahaLuhem/platform_adaptive_widgets#71

Closed

wolfenrain mentioned this pull request Nov 3, 2026

[a11y] have a way to test that a slider exposes its value flutter/flutter#195889

Open

QuncCccccc requested a review from dkwingsmt November 3, 2026 22:36

dkwingsmt added the CICD Run CI/CD label Nov 10, 2026

dkwingsmt approved these changes Nov 10, 2026

View reviewed changes

dkwingsmt requested a review from pjkammer November 10, 2026 07:49

pjkammer approved these changes Nov 11, 2026

View reviewed changes

Merge branch 'main' into fix/cupertino-slider-disabled-appearance

287ac12

flutter-dashboard Bot removed the CICD Run CI/CD label Nov 11, 2026

pjkammer added CICD Run CI/CD autosubmit Merge PR when tree becomes green via auto submit App labels Nov 11, 2026

auto-submit Bot merged commit e81cfde into flutter:main Nov 11, 2026
14 checks passed

engine-flutter-autoroll mentioned this pull request Nov 12, 2026

Roll Packages from 653628e8a646 to 14f9933a8cd6 (9 revisions) flutter/flutter#196450

Merged

justinmc mentioned this pull request Nov 13, 2026

Flutter Notable Commits - 2026 flutter/flutter#181433

Open

Navigation Menu

Repository navigation

[cupertino_ui] Dim disabled CupertinoSlider controls - #13419

[cupertino_ui] Dim disabled CupertinoSlider controls#13419
auto-submit[bot] merged 3 commits into
flutter:mainfrom
Wreos:fix/cupertino-slider-disabled-appearance

Wreos commented Oct 25, 2026 •

edited

Loading

Uh oh!

gemini-code-assist Bot left a comment

Uh oh!

gemini-code-assist Bot Oct 25, 2026

Uh oh!

Wreos Oct 25, 2026 •

edited

Loading

Uh oh!

gemini-code-assist Bot Oct 25, 2026

Uh oh!

Wreos Oct 25, 2026

Uh oh!

dkwingsmt left a comment •

edited

Loading

Uh oh!

Uh oh!

Reviewers

Uh oh!

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

Conversation

Wreos commented Oct 25, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Screenshots

Pre-Review Checklist

Footnotes

Uh oh!

gemini-code-assist Bot left a comment

Choose a reason for hiding this comment

Code Review

Uh oh!

gemini-code-assist Bot Oct 25, 2026

Choose a reason for hiding this comment

Uh oh!

Wreos Oct 25, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

gemini-code-assist Bot Oct 25, 2026

Choose a reason for hiding this comment

Uh oh!

Wreos Oct 25, 2026

Choose a reason for hiding this comment

Uh oh!

dkwingsmt left a comment • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Reviewers

Uh oh!

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

Wreos commented Oct 25, 2026 •

edited

Loading

Wreos Oct 25, 2026 •

edited

Loading

dkwingsmt left a comment •

edited

Loading