[Impeller] Playground expanded role by flar · Pull Request #188889 · flutter/flutter

flar · 2026-07-01T21:59:08Z

Currently the set of Playground tests in the Impeller directory is the main way in which we test changes to the renderer. Unfortunately, these tests don't test much code unless they are either run in the impeller_golden_tests executable, or if they are run with --enable_playground. Without those conditions the test harness simply allows the caller to construct a DisplayList and then immediately returns true without seeing if it successfully renders anything. This PR expands the role of these Playground tests in 2 ways:

The tests can now generate golden images directly from impeller_unittests without needing a separate executable (impeller_golden_tests). If you specify the flag --golden_output_dir=<directory> then golden images for any test marked as a golden test will be written there along with a digest of the files written.
The tests will always render their target at least once for each Playground test, whether or not goldens are being generated or the playground is enabled, expanding the amount of code that is tested on each run.

Note that some tests were found to fail when you actually tried to render something. Some of them with trivial fixes are fixed in this PR while others which require more investigation have been deferred to follow-on issues, such as:

The Interop RuntimeEffect test: #188882
The StencilMask tests (with playground window): #188884
The MassiveScalingTexture test: #189286
The SepiaTone subpass tests: #189287

Pre-launch Checklist

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…xpanded-role

gemini-code-assist

Code Review

This pull request restructures Impeller's testing and playground infrastructure by extracting screenshotting and golden digest management into a dedicated testing component, updating various tests to use the new Screenshotter and GoldenDigestManager, and wrapping ImGui controls with playground checks. Feedback on these changes highlights several critical issues, including potential null pointer dereferences when retrieving the graphics context, an out-of-bounds memory read in CalculateSpaceBetweenUI due to missing boundary checks on the vertical coordinate, undefined behavior from a missing fallback return in Screenshotter::MakeScreenshot, potential malformed JSON generation from unescaped characters in GoldenDigestManager::AddDimension, and encapsulation violations in Playground::GetTypographerContext.

gemini-code-assist · 2026-07-10T08:20:50Z

+void GoldenDigestManager::AddDimension(const std::string& name,
+                                       const std::string& value) {
+  std::stringstream ss;
+  ss << "\"" << value << "\"";
+  dimensions_[name] = ss.str();
+}


If the value parameter contains double quotes (") or backslashes (\\), writing it directly to the JSON stream will result in malformed JSON. Since value can be a GPU model description (which often contains brand names or version strings with special characters), it should be properly escaped.\n\nConsider escaping double quotes and backslashes in the dimension value.

void GoldenDigestManager::AddDimension(const std::string& name,\n const std::string& value) {\n std::string escaped_value;\n for (char c : value) {\n if (c == '\"') {\n escaped_value += \"\\\\\\\";\n } else if (c == '\\\\') {\n escaped_value += \"\\\\\\\\\\\\";\n } else {\n escaped_value += c;\n }\n }\n std::stringstream ss;\n ss << \"\\\"\" << escaped_value << \"\\\"\";\n dimensions_[name] = ss.str();\n}

We should really be constructing the output with a JSON utility that would automatically protect the data for us. I opted not to pursue cobbling this together for now.

flar · 2026-07-10T21:38:52Z

To be clear on the golden image generation, this feature is not yet used to create the golden images for our pre-submit testing. I will work on switching the mechanism over in a future PR as that will also have (different) wide-ranging changes and I want to work on making sure we generate compatible output. For now, I'm leaving the existing impeller_golden_tests executable in charge of doing pre-submit image production even while adding the same functionality (really just a single method) into impeller_unittests.

jason-simmons

LGTM - just a few nits

jason-simmons · 2026-07-13T21:15:43Z

-                            const std::string_view& font_fixture,
-                            DlPoint position,
-                            const TextRenderOptions& options) {
+std::optional<DlRect> RenderTextInCanvasSkia(


Consider returning absl::StatusOr here (and in CalculateSpaceBetweenUI)

This complicated the code a fair bit since the return value was only used in one spot and all of the others expected to either ignore the return (you can't with StatusOr) or just do an EXPECT/ASSERT_TRUE which also doesn't work on StatusOr (you need to add .ok())

But, check out the last couple of commits and see...

…xpanded-role

flutter/flutter@cf9e8af...846664b 2026-07-14 [email protected] Roll Skia from dfcff99566c3 to 88954ef8f36d (1 revision) (flutter/flutter#189440) 2026-07-14 [email protected] refactor: remove material import from scrollable_semantics_test and selectable_region_context_menu_test (flutter/flutter#186611) 2026-07-14 [email protected] Roll Skia from 3d1fc554f1a2 to dfcff99566c3 (17 revisions) (flutter/flutter#189428) 2026-07-14 [email protected] Roll Dart SDK from 2c587df8f05a to 05bf153370c4 (5 revisions) (flutter/flutter#189426) 2026-07-14 [email protected] [flutter_tools] Remove web hot reload flag (flutter/flutter#185994) 2026-07-14 [email protected] [iOS] Fix flaky keyboard animation test (flutter/flutter#189353) 2026-07-14 [email protected] [Impeller] Playground expanded role (flutter/flutter#188889) 2026-07-14 [email protected] Roll pub packages (flutter/flutter#189409) 2026-07-13 [email protected] Update lock-threads dependency to 6.0.2 (flutter/flutter#189053) 2026-07-13 49699333+dependabot[bot]@users.noreply.github.com Bump actions/labeler from 6.1.0 to 6.2.0 in the all-github-actions group (flutter/flutter#189396) 2026-07-13 [email protected] Remove outdated todo about `analysis bug on Windows` and update condition to also perform `analysis on windows` (flutter/flutter#189283) 2026-07-13 [email protected] Add more 0x0 size tests part 4 (flutter/flutter#185187) 2026-07-13 [email protected] Roll Packages from 20928d5 to ad2eab1 (18 revisions) (flutter/flutter#189387) 2026-07-13 [email protected] [flutter_tools] Fix ADB device listing output parsing regression (flutter/flutter#189369) 2026-07-13 [email protected] Stop running most Mac x64 builders that have Mac ARM equivalents on master (flutter/flutter#189301) 2026-07-13 [email protected] Move a few benchmarks from x64 Intel Macs to ARM (flutter/flutter#189377) 2026-07-13 [email protected] Add note that `hcpp` needs impeller (flutter/flutter#189382) 2026-07-13 [email protected] Roll Fuchsia Linux SDK from vhIlDkWIy21IrlB9E... to oOETA0ISPouDt2xBo... (flutter/flutter#189349) 2026-07-13 [email protected] [flutter_tools] Respect mustMatchAppBuild on Windows native assets (flutter/flutter#186788) 2026-07-13 [email protected] Roll Skia from 8bf65996caba to 3d1fc554f1a2 (2 revisions) (flutter/flutter#189350) 2026-07-13 [email protected] Roll Dart SDK from 0fc1668c4af4 to 2c587df8f05a (9 revisions) (flutter/flutter#189351) 2026-07-13 [email protected] [web] Fall back to full CJK fonts for characters not covered by split slices (flutter/flutter#188890) 2026-07-13 [email protected] Take Mac tool_integration_tests_* out of bringup (flutter/flutter#189368) 2026-07-13 [email protected] [hooks] Roll record_use to 1.0 and unpin (flutter/flutter#189366) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC [email protected],[email protected] on the revert to ensure that a human is aware of the problem. To file a bug in Packages: 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

…ts on Mac Minis used by CI flutter#188889 started using the Impeller rendering backends in playground tests run by the impeller_unittests harness. Since then, runs of OpenGLESSDF tests on macOS CI have been flaky. These flakes show up as gtest-parallel child processes that fail with exit code -5 (SIGTRAP). The affected CI machines are M1 Mac Minis (hardware model "Macmini9,1") This is an experiment to see if limiting the number of test cases run in parallel on these machines reduces the crashes. See flutter#189748

flar added 4 commits July 1, 2026 11:01

[Impeller] Playground tests will always run one frame

efd79ca

fix vulkan playground validations

0d70bbc

skip broken interop test on OpenGL

352df7a

disable StencilMask until bug is fixed

f310f8f

github-actions Bot added a: text input Entering text in a text field or keyboard related problems engine flutter/engine related. See also e: labels. e: impeller Impeller rendering backend issues and features requests labels Jul 1, 2026

flar mentioned this pull request Jul 1, 2026

[Impeller] Playground tests will always run one frame #187603

Closed

10 tasks

flar added the CICD Run CI/CD label Jul 1, 2026

flar added 15 commits July 1, 2026 20:20

fix non-Mac linker errors

82d4e4d

more non-Mac linker errors

4ee542d

clang tidy changes

6bea832

fix Mac tests failing under CI Metal validation flags

0c20bd5

golden digests and better configuration of playground golden settings

01c9588

don't write golden digest if there were errors

6e7ed13

fix MaintainsSpace tests

c1ff1af

fix vulkan unittests build

6c53a6a

fix Vulkan validation errors

52d47d0

fix metal validation errors

b0f733e

always use metal validation even in local runs

3bc3b68

fix win build

b4cf5b3

eliminate overwrite of pipeline desc defaults

612adb9

reposition SWIFTSHADER initialization

478ab2e

Merge branch 'master' of github.com:flutter/flutter into playground-e…

7171c6c

…xpanded-role

flar marked this pull request as ready for review July 10, 2026 08:16

gemini-code-assist Bot reviewed Jul 10, 2026

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flar added 2 commits July 10, 2026 11:34

gemini feedback

bdace5b

exempt MassiveScalingMatrixImageFilter on GL backends

85e9e4d

flar mentioned this pull request Jul 10, 2026

[Impeller] CanSepiaToneThenSwizzleWithSubpasses is crashing in CI #189287

Open

exempt CanSepiaToneThenSwizzleWithSubpasses on GL backends

9313d54

flar mentioned this pull request Jul 10, 2026

[Impeller] MassiveScalingMatrixImageFilter test is crashing on CI #189286

Open

flar requested review from b-luk and jason-simmons July 10, 2026 21:34

flar mentioned this pull request Jul 10, 2026

[Impeller] InteropPlaygroundTest.CanCreateFragmentProgramColorFilters does not run with playground enabled #188882

Open

jason-simmons previously approved these changes Jul 13, 2026

View reviewed changes

flar added 3 commits July 13, 2026 17:26

review feedback

2c58e7f

fix Vulkan OOM (due to fragmentation) errors

36f615e

Merge branch 'master' of github.com:flutter/flutter into playground-e…

7124792

…xpanded-role

flar dismissed jason-simmons’s stale review via 7124792 July 14, 2026 00:36

flar requested a review from jason-simmons July 14, 2026 00:38

jason-simmons approved these changes Jul 14, 2026

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flar added the autosubmit Merge PR when tree becomes green via auto submit App label Jul 14, 2026

auto-submit Bot added this pull request to the merge queue Jul 14, 2026

Merged via the queue into flutter:master with commit 547e77e Jul 14, 2026
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flutter-dashboard Bot removed the autosubmit Merge PR when tree becomes green via auto submit App label Jul 14, 2026

engine-flutter-autoroll mentioned this pull request Jul 14, 2026

Roll Flutter from cf9e8afe9a5e to 846664bf191a (24 revisions) flutter/packages#12200

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jason-simmons mentioned this pull request Jul 22, 2026

Reduce the number of gtest-parallel workers when running Impeller tests on Mac Minis used by CI #189813

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[Impeller] Playground expanded role#188889

[Impeller] Playground expanded role#188889
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