Fix/predictive back event swipe edge out of bounds by muhammadkamel · Pull Request #185140 · flutter/flutter

muhammadkamel · 2026-04-16T06:49:07Z

This PR addresses a RangeError in PredictiveBackEvent.fromMap that occurs on Android devices when the predictive back gesture provides an unexpected swipeEdge index.

Description

On some Android 14+ devices/ROMs, the platform can send a swipeEdge value of 2 (BackEvent.EDGE_NONE) for button-triggered predictive back events. Since SwipeEdge previously only contained left (0) and right (1), indexing SwipeEdge.values with 2 caused a crash.

This PR adds SwipeEdge.none to represent EDGE_NONE, maps platform values explicitly in fromMap, and updates isButtonEvent accordingly. Unknown or out-of-range values are mapped to SwipeEdge.none rather than throwing a RangeError.

Decoupling split

Per the decoupling guidance, this PR is now scoped to framework/services changes only:

packages/flutter/lib/src/services/predictive_back_event.dart
packages/flutter/test/services/predictive_back_event_test.dart

Material widget tests and transition behavior tests have been removed from this PR and will be ported to material_ui once that package is ready to accept PRs.

A minimal one-line exhaustiveness update in predictive_back_page_transitions_builder.dart (SwipeEdge.none || null) is retained because adding the new enum value requires it for compilation.

Issues Fixed

Fixes RangeError crash in PredictiveBackEvent.fromMap during back navigation on Android. Closes [Android] PredictiveBackEvent.fromMap does not guard against invalid swipeEdge value #186168

Pre-launch Checklist

…eEdge index Android can send a swipeEdge value of 2 (or other out-of-range values) which caused a RangeError crash since SwipeEdge only has indices 0 (left) and 1 (right). Clamp the index to the valid range to handle unknown future values gracefully.

…dation

google-cla · 2026-04-16T06:49:23Z

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gemini-code-assist

Code Review

This pull request modifies PredictiveBackEvent.fromMap to clamp the swipeEdge index to the valid range of SwipeEdge.values, preventing RangeError exceptions when receiving unexpected values from the platform. The test suite was updated to verify clamping behavior for negative and out-of-bounds indices. A review comment suggests casting the swipeEdge value to num before converting to int to improve robustness against platform-specific serialization differences.

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

…f-bounds

muhammadkamel · 2026-04-16T07:05:17Z

Hi @Piinks,

Could you please review this PR? It fixes a RangeError crash in PredictiveBackEvent that occurs when the platform sends an out-of-range swipeEdge index on Android 13+.

I’ve implemented defensive clamping and added regression tests to ensure stability. I am hoping to get this landed as soon as possible so it can be included in the upcoming 3.44.0 stable release.

Thank you!

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…events

…ttps://github.com/muhammadkamel/flutter into fix/predictive-back-event-swipe-edge-out-of-bounds

navaronbracke

Just some remarks about aligning with the specification in the docs.

…ckEvent On some Android 14+ devices, the platform sends swipeEdge=2 (BackEvent.EDGE_NONE) for button-triggered predictive back events, causing a RangeError in PredictiveBackEvent.fromMap. - Add SwipeEdge.none to the enum to explicitly represent EDGE_NONE - Map swipeEdge int values explicitly (0→left, 1→right, 2→none, _→none) instead of indexing SwipeEdge.values directly - Update isButtonEvent to return true when swipeEdge == SwipeEdge.none - Expand test coverage to 100% of PredictiveBackEvent logic Fixes: RangeError crash during predictive back on Android 14+

…f-bounds

muhammadkamel · 2026-04-16T14:02:58Z

@navaronbracke

I’ve made some changes to ensure alignment with the native documentation.

muhammadkamel · 2026-04-16T14:10:14Z

Hi @justinmc
This PR should be merged ASAP as a hotfix.

…riggered events

Piinks · 2026-04-16T15:28:18Z

I am hoping to get this landed as soon as possible so it can be included in the upcoming 3.44.0 stable release.

This release has already been cut.

This PR should be merged ASAP as a hotfix.

Is there an open issue? If not please file one. We need to be able to evaluate the impact and risk before determining if we will hotfix something.

…ge-out-of-bounds

justinmc

Just some nits here.

@muhammadkamel Could you file an issue as suggested by @Piinks?

muhammadkamel · 2026-05-07T02:19:18Z

@Piinks
@justinmc

I created an issue report for this PR: #186168

…ntation for touch event handling

…BackEvent.fromMap

justinmc

LGTM 👍 . Thank you for the thorough issue you created @muhammadkamel!

This PR will have to wait until after the code freeze unfortunately. I'll put it in draft mode and we'll come back to it.

maRci002 · 2026-05-14T12:12:48Z

Same PR as #183642

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Piinks · 2026-06-24T19:08:11Z

I've marked this PR as not ready to port to flutter/packages yet.
We'll provide instructions to move this change over to material_ui once it is ready to receive PRs. Thank you!

The changes in the services library will remain here after.

Piinks · 2026-06-25T00:13:33Z

Advice for PR splitting: Since this touches material/cupertino along with other parts of flutter/flutter, it will need to be split up.

If the material/cupertino changes are dependent on the other non-material/cupertino changes in this PR, then the material/cupertino changes will need to wait for them to roll to stable before they can be ported over to material_ui/cupertino_ui in flutter/packages (which uses the stable branch).

If that is the case here, consider opening a new PR with the non-material/cupertino changes to move forward with so that waiting period can be reduced. Up to you!

muhammadkamel · 2026-07-03T07:54:03Z

@Piinks I've split this PR per the decoupling guidance:

Framework/services changes remain here (predictive_back_event.dart + tests).
Material widget tests (right-edge swipe and button-triggered EDGE_NONE coverage) have been removed and will be ported to material_ui once that package is ready.
A minimal one-line exhaustiveness case for SwipeEdge.none is kept in predictive_back_page_transitions_builder.dart since the new enum value is required for compilation.

Happy to open the material_ui follow-up when instructions are available.

Remove Material widget tests and transition comments from this PR. Those will be ported to material_ui once that package accepts PRs. Keep the minimal SwipeEdge.none exhaustiveness case in the material transition builder required for compilation after adding the enum value.

Piinks · 2026-11-02T22:51:18Z

Hey @muhammadkamel would you like to continue working on this PR? PRs marked as drafts are typically not reviewed, when you are ready, please mark it as ready for review.

github-actions · 2026-11-03T04:52:17Z

This pull request contains changes to Material or Cupertino, which are currently frozen in this repository.

Changes should be made in material_ui and/or cupertino_ui in the flutter/packages repository.

Please refer to #188444 for instructions.

gemini-code-assist

Code Review

This pull request introduces a new SwipeEdge.none enum value to represent button-triggered back events, corresponding to Android's BackEvent.EDGE_NONE. It updates PredictiveBackEvent parsing, isButtonEvent detection, and predictive back page transitions to handle this new edge type, and adds comprehensive unit tests. Feedback is provided to simplify a redundant pattern in the swipeEdge switch expression.

gemini-code-assist · 2026-11-03T04:52:47Z

+      swipeEdge: switch (map['swipeEdge']) {
+        0 => SwipeEdge.left,
+        1 => SwipeEdge.right,
+        2 || _ => SwipeEdge.none,
+      },


The pattern 2 || _ is redundant because the wildcard pattern _ already matches any value, including 2. Simplifying this to just _ makes the code cleaner, more idiomatic, and avoids potential compiler warnings about redundant patterns.

Suggested change

swipeEdge: switch (map['swipeEdge']) {

0 => SwipeEdge.left,

1 => SwipeEdge.right,

2 || _ => SwipeEdge.none,

},

swipeEdge: switch (map['swipeEdge']) {

0 => SwipeEdge.left,

1 => SwipeEdge.right,

_ => SwipeEdge.none,

},

References

Suggest simplification and refactoring to enhance readability and maintainability. ^(link)

muhammadkamel · 2026-11-03T04:58:53Z

Thanks @Piinks, marked ready. One question on the code freeze check:

Adding SwipeEdge.none (Android's documented BackEvent.EDGE_NONE, API 36) requires a one-line exhaustiveness update in the frozen packages/flutter/lib/src/material/predictive_back_page_transitions_builder.dart, otherwise the framework doesn't compile. No behavior change there.

The material_ui side is already ported and approved: flutter/packages#12502 (its _ fallback handles none).

Can this compile-only change get a freeze exemption, or should the PR wait until Material is removed from the framework?

Piinks · 2026-11-10T22:06:46Z

Can this compile-only change get a freeze exemption, or should the PR wait until Material is removed from the framework?

@justinmc can advise here thanks!

muhammadkamel added 2 commits April 16, 2026 08:29

test: add unit tests for PredictiveBackEvent.fromMap parsing and vali…

ef8f1f2

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github-actions Bot added the framework flutter/packages/flutter repository. See also f: labels. label Apr 16, 2026

gemini-code-assist Bot reviewed Apr 16, 2026

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Comment thread packages/flutter/lib/src/services/predictive_back_event.dart Resolved

muhammadkamel and others added 2 commits April 16, 2026 08:52

Update packages/flutter/lib/src/services/predictive_back_event.dart

10794e3

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Merge branch 'master' into fix/predictive-back-event-swipe-edge-out-o…

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muhammadkamel force-pushed the fix/predictive-back-event-swipe-edge-out-of-bounds branch from 0f01f2d to 3304a67 Compare April 16, 2026 06:55

navaronbracke requested changes Apr 16, 2026

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Comment thread packages/flutter/lib/src/services/predictive_back_event.dart Resolved

muhammadkamel added 3 commits April 16, 2026 11:31

Merge branch 'master' into fix/predictive-back-event-swipe-edge-out-o…

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…f-bounds

feat: add SwipeEdge.none to support button-triggered predictive back …

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Merge branch 'fix/predictive-back-event-swipe-edge-out-of-bounds' of h…

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…ttps://github.com/muhammadkamel/flutter into fix/predictive-back-event-swipe-edge-out-of-bounds

github-actions Bot added the p: material_ui material_ui package in flutter/packages label Apr 16, 2026

muhammadkamel requested a review from navaronbracke April 16, 2026 10:18

navaronbracke requested changes Apr 16, 2026

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muhammadkamel added 2 commits April 16, 2026 16:00

Merge branch 'master' into fix/predictive-back-event-swipe-edge-out-o…

ad5446c

…f-bounds

muhammadkamel added 2 commits April 16, 2026 16:16

fix: handle SwipeEdge.none in predictive back transition for button-t…

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…riggered events

fix: update documentation for touchOffset in PredictiveBackEvent

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Merge branch 'flutter:master' into fix/predictive-back-event-swipe-ed…

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navaronbracke mentioned this pull request May 5, 2026

[Android] Implement safe parsing and null-safety inside PredictiveBackEvent.fromMap #186024

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dkwingsmt requested a review from justinmc May 6, 2026 18:13

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Comment thread packages/flutter/lib/src/services/predictive_back_event.dart Resolved

Comment thread packages/flutter/lib/src/services/predictive_back_event.dart Resolved

Comment thread packages/flutter/test/material/predictive_back_page_transitions_builder_test.dart Resolved

fix(predictive_back_event): clarify swipe edge enum and update docume…

5ad1d5b

…ntation for touch event handling

navaronbracke reviewed May 7, 2026

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Comment thread packages/flutter/lib/src/services/predictive_back_event.dart Resolved

fix(predictive_back_event): simplify swipe edge mapping in Predictive…

711e858

…BackEvent.fromMap

muhammadkamel requested a review from justinmc May 7, 2026 13:20

justinmc previously approved these changes May 8, 2026

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justinmc added the waiting for code freeze This PR is waiting for a code freeze to resolve. label May 8, 2026

justinmc marked this pull request as draft May 8, 2026 18:37

muhammadkamel added 2 commits May 22, 2026 00:40

Merge branch 'master' into fix/predictive-back-event-swipe-edge-out-o…

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Merge branch 'flutter:master' into fix/predictive-back-event-swipe-ed…

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muhammadkamel mentioned this pull request Jun 2, 2026

[Android] Predictive back animations in 3-button navigation mode #183635

Open

muhammadkamel mentioned this pull request Jun 17, 2026

Fix RangeError in PredictiveBackEvent.fromMap #187244

Closed

10 tasks done

Merge branch 'flutter:master' into fix/predictive-back-event-swipe-ed…

c524d3d

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Piinks added the Decoupling: Not ready to port yet Instructions will be provided when this is ready to move to flutter/packages. label Jun 24, 2026

Piinks added the Decoupling: Split PR The PR will need to be split to separate Material & Cupertino changes label Jun 25, 2026

muhammadkamel dismissed justinmc’s stale review via e72123a July 3, 2026 07:53

muhammadkamel force-pushed the fix/predictive-back-event-swipe-edge-out-of-bounds branch from e72123a to 25755c3 Compare July 29, 2026 08:05

This was referenced Aug 18, 2026

Fix RangeError in PredictiveBackEvent when Android sends EDGE_NONE #191306

Open

[material_ui] Handle unknown swipe edges in predictive back transitions flutter/packages#12502

Open

maRci002 mentioned this pull request Oct 5, 2026

Android: Support predictive back from 3-button navigation #183642

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10 tasks done

muhammadkamel marked this pull request as ready for review November 3, 2026 04:52

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muhammadkamel requested a review from justinmc November 10, 2026 22:13

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Description

Decoupling split

Issues Fixed

Pre-launch Checklist

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