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Allow zero cross axis extent in SliverGridDelegateWithMaxCrossAxisExtent - #194858

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YeungKC:fix-sliver-grid-zero-cross-axis
Nov 6, 2026
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auto-submit[bot] merged 5 commits into
flutter:masterfrom
YeungKC:fix-sliver-grid-zero-cross-axis

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@YeungKC

@YeungKC YeungKC commented Oct 20, 2026

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SliverGridDelegateWithMaxCrossAxisExtent asserts crossAxisExtent > 0.0 in _debugAssertIsValid. When the view size is zero, the grid gets a cross axis extent of 0.0 and the assert fails. This occurs, for example, when the app starts while the device screen is locked.

getLayout already supports a zero cross axis extent:

  • It clamps crossAxisCount to a minimum of 1. The code comment says that the count can be zero "when the window size is 0".
  • It clamps usableCrossAxisExtent to a minimum of 0.0.

Thus, only the assert rejects this value. This PR changes the assert to crossAxisExtent >= 0.0. A negative extent still fails the assert. SliverGridDelegateWithFixedCrossAxisCount does not assert on the cross axis extent, so the two delegates now agree on a zero extent.

Fixes #130069

Tests

I added a regression test to packages/flutter/test/widgets/grid_view_test.dart. The test puts a GridView.extent in a SizedBox with a width of 0.0. It makes sure that layout throws no exception.

New test test/widgets, test/material, test/cupertino, test/rendering
Before Fails: 'crossAxisExtent > 0.0': is not true (sliver_grid.dart line 493) 72 failures
After Passes (grid_view_test.dart: +30, all tests passed) 72 failures, the same 72 tests as before

The 72 failures also occur on the base commit without this change. They are golden image tests and font tests that depend on the local environment.

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  • 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 in-code documentation (doc comments with ///). No doc change is necessary.
  • 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). This PR does not add a feature.
  • I added new tests to check the change I am making, or this PR is test-exempt.
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  • All existing and new tests are passing. The framework tests pass locally, except tests that also fail on the base commit. The other tests run only in CI.

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@flutter-dashboard flutter-dashboard Bot added the CICD Run CI/CD label Oct 20, 2026
@github-actions github-actions Bot added framework flutter/packages/flutter repository. See also f: labels. f: scrolling Viewports, list views, slivers, etc. labels Oct 20, 2026

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Code Review

This pull request modifies the assertion in SliverGridDelegateWithMaxCrossAxisExtent to allow a crossAxisExtent of zero or greater, and adds a regression test to verify that GridView.extent can lay out with a zero cross-axis extent without throwing an exception. There are no review comments, and I have no feedback to provide.

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LGTM, zero cross-axis extent is treated as valid across the codebase + the reason the assert was added (0/0 division) was fixed with a clamp in #112982, so release mode already allows for it.

victorsanni
victorsanni previously approved these changes Oct 28, 2026

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LGTM, zero cross-axis extent is treated as valid across the codebase + the reason the assert was added (0/0 division) was fixed with a clamp in #112982, so release mode already allows for it.

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Hi, is this ready for re-review? Please remember to request a review if it is, so it gets back into the review queue.

@YeungKC
YeungKC requested a review from victorsanni October 30, 2026 13:34
victorsanni
victorsanni previously approved these changes Nov 5, 2026

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LGTM with more comments.

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LGTM

@victorsanni victorsanni added the autosubmit Merge PR when tree becomes green via auto submit App label Nov 5, 2026
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auto-submit Bot added this pull request to the merge queue Nov 5, 2026
Merged via the queue into flutter:master with commit c0921ab Nov 6, 2026
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@flutter-dashboard flutter-dashboard Bot removed the autosubmit Merge PR when tree becomes green via auto submit App label Nov 6, 2026
auto-submit Bot pushed a commit to flutter/packages that referenced this pull request Nov 6, 2026
Roll Flutter from 3623d2d34543 to 09175cdeac89 (61 revisions)

flutter/flutter@3623d2d...09175cd

2026-11-06 [email protected] Roll Skia from ae35b7b2221f to 793b8ac73d4b (3 revisions) (flutter/flutter#196091)
2026-11-06 [email protected] [web] Rasterize scenes at the size passed to `FlutterView.render` (flutter/flutter#196052)
2026-11-06 [email protected] Roll Skia from 4aa043a81e0c to ae35b7b2221f (1 revision) (flutter/flutter#196086)
2026-11-06 [email protected] Roll Fuchsia Linux SDK from Fqe3UlLwAohsPbsCS... to KIc0XZbhLmvDpTluZ... (flutter/flutter#196085)
2026-11-06 [email protected] Allow a zero scale change in InteractiveViewer (flutter/flutter#194949)
2026-11-06 [email protected] Roll Skia from dd5c2553a856 to 4aa043a81e0c (2 revisions) (flutter/flutter#196079)
2026-11-06 [email protected] [web] Keep ImageFilter.blur bounds in equality and description (flutter/flutter#196013)
2026-11-06 [email protected] iOS: Remove unused PlatformViewIOS setup from FlutterPlatformViewsTest (flutter/flutter#196033)
2026-11-06 [email protected] Serialize LoggerTests that mutate the shared Logger (flutter/flutter#196028)
2026-11-06 [email protected] Use reverseDuration for the AnimatedCrossFade size animation (flutter/flutter#194860)
2026-11-05 [email protected] Roll Skia from a5aacd103e68 to dd5c2553a856 (8 revisions) (flutter/flutter#196073)
2026-11-05 [email protected] Fix ListWheelScrollView null check error when it reads itemIndex before content dimensions are set (flutter/flutter#194859)
2026-11-05 [email protected] Allow zero cross axis extent in SliverGridDelegateWithMaxCrossAxisExtent (flutter/flutter#194858)
2026-11-05 [email protected] Revert: Allow color delta tolerance in in-memory fuzzy image comparator (flutter/flutter#196067)
2026-11-05 [email protected] Revert: Mitigate snapshot race in 3D transform test by reducing loop density (flutter/flutter#196066)
2026-11-05 [email protected] Delegate createStream in ResizeImage and ScrollAwareImageProvider (flutter/flutter#194756)
2026-11-05 [email protected] [iOS] Introduce FlutterShell and move thread host and profiler (flutter/flutter#195388)
2026-11-05 [email protected] [web] Support FragmentShader.getImageSampler on CanvasKit and Skwasm (flutter/flutter#195854)
2026-11-05 [email protected] Deprecates setFloat API (flutter/flutter#195505)
2026-11-05 [email protected] [flutter_tools] Remove public GlobalToolContext and globals from runner (flutter/flutter#195561)
2026-11-05 [email protected] Defer TLHC PlatformViewWrapper frame post and avoid initial 1x1 buffer resize (flutter/flutter#195861)
2026-11-05 [email protected] Roll Skia from b5abed66da86 to a5aacd103e68 (17 revisions) (flutter/flutter#196054)
2026-11-05 [email protected] Made `FlutterWindowControllerSizeTest.SizedToContentNotResizable` more robust (flutter/flutter#195845)
2026-11-05 [email protected] Update docs for contributor ladder (flutter/flutter#196011)
2026-11-05 [email protected] [Impeller] Use the transfer stage for the Vulkan readback barrier (flutter/flutter#194991)
2026-11-05 [email protected] Remove Mac mac_unopt builder (flutter/flutter#196027)
2026-11-05 [email protected] Updated Instructions for Determining Gradle Version for `gradle_dists` in CIPD (flutter/flutter#193310)
2026-11-05 [email protected] Move ios_app_with_extensions_test into the tool integration shard (flutter/flutter#195609)
2026-11-05 [email protected] [web] Respect Uint8List view bounds when detecting animated WebP/GIF (flutter/flutter#196010)
2026-11-05 [email protected] Add platform_views_layout to build_tests so iOS/Android build breaks are caught in presubmit (flutter/flutter#192985)
2026-11-05 [email protected] [flutter_tools] Detect macOS TCC permission crashes and provide diagnostic guidance (flutter/flutter#192432)
2026-11-05 [email protected] Roll Packages from 670b30e to 0478162 (15 revisions) (flutter/flutter#196047)
2026-11-05 [email protected] [web] Support Skwasm rendering without bitmap capture (flutter/flutter#195103)
2026-11-05 [email protected] [flutter_tools] Reland fix for local CanvasKit asset paths on Windows (flutter/flutter#195770)
2026-11-05 [email protected] Roll Skia from f96be51af95d to b5abed66da86 (14 revisions) (flutter/flutter#196017)
2026-11-05 [email protected] Split chrome web engine test drone (flutter/flutter#195873)
2026-11-05 [email protected] Roll Dart SDK from c9153304136a to 6623b84628f3 (1 revision) (flutter/flutter#196026)
2026-11-05 [email protected] Roll ICU from 4fe960221710 to a0ea93436c52 (6 revisions) (flutter/flutter#196025)
2026-11-05 [email protected] Add more guidance in README and AGENTS for contributing to flutter_tools (flutter/flutter#195998)
2026-11-05 [email protected] Roll Fuchsia Linux SDK from p0HDXLISPIElJfSz7... to Fqe3UlLwAohsPbsCS... (flutter/flutter#196019)
2026-11-05 [email protected] Roll Dart SDK from e362a23e9738 to c9153304136a (18 revisions) (flutter/flutter#196014)
2026-11-05 [email protected] [Impeller] Fix dilation input bounds when clipping saveLayers (flutter/flutter#195652)
2026-11-05 [email protected] Add `variantOf` to the M3E migration checklist (flutter/flutter#195099)
2026-11-05 [email protected] [flutter_tools] Eliminate globals from remaining subsystem files (flutter/flutter#195555)
2026-11-05 [email protected] Fix gap flipping when dragging variable height reorderable items (flutter/flutter#194478)
2026-11-05 [email protected] [A11y] Send un-merged SemanticsNodes in the same update that first references them (flutter/flutter#195829)
...
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SliverGrid throws assertion while screen is locked

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