fix: prevent black screen by setting surface event before format change

[winnerspiros]

See commit message for details. Fixes black screen on launch caused by surface format change blocking the draw thread.

Summary by CodeRabbit

• Bug Fixes
  • Optimized graphics rendering synchronization on Android to prevent frame processing delays during color format transitions. Addressed a timing issue that could cause temporary performance stalls on certain devices.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 9c1da771-ae75-4a4f-be42-5263048b7952

📥 Commits

Reviewing files that changed from the base of the PR and between 59300b0 and 90dc644.

📒 Files selected for processing (1)

• osu.Android/OsuGameActivity.cs

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📝 Walkthrough

Walkthrough

This PR adjusts the Vulkan RGB565 recovery synchronization in OsuGameActivity.SurfaceChanged. When RGB565 is detected under Vulkan, surfaceEvent is now signaled before calling holder.SetFormat(Rgba8888) to prevent the draw thread from blocking during the synchronous surface teardown, followed by dedicated logging and removal of an immediate reset.

Changes

Vulkan RGB565 Recovery Synchronization

Layer / File(s)	Summary
Vulkan RGB565 recovery synchronization osu.Android/OsuGameActivity.cs	When RGB565 is detected under Vulkan, surfaceEvent is set before requesting the format change (guarded by valid width/height), a dedicated debug log message is added after SetFormat, and the previous immediate surfaceEvent.Reset() is removed to allow the draw thread to progress during synchronous teardown.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~18 minutes

The change involves careful synchronization logic with threading implications. Understanding the interaction between surfaceEvent, SetFormat teardown behavior, and draw-thread timing requires examining the complete control flow and potential race conditions. The logic is concentrated in one method but demands careful review of synchronization guarantees and state transitions.

Poem

🐰 A surface needs sync when RGB565 shows,
Set the signal first, before teardown flows,
Draw-thread keeps dancing while formats align,
No blocking here—just perfect timing design! ✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'fix: prevent black screen by setting surface event before format change' directly and clearly describes the main change: preventing a black screen by adjusting when the surface event is set relative to the format change call, which is exactly what the changeset accomplishes.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/black-screen-surface-teardown

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[winnerspiros]

Closing — the fix introduces a data race between the draw thread reading surfaceGlobalRef and SurfaceDestroyed freeing it. The correct fix needs to handle the surface lifecycle more carefully.