support grayscale (including strip rendering) in simulator

[rmmh]

This greatly improves fidelity, both graphically and for OOM testing.

before/after

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 87d85579-0ef9-4ea3-8e74-32b6bdb8da92

📥 Commits

Reviewing files that changed from the base of the PR and between 23988a2 and d4df89f.

📒 Files selected for processing (2)

• src/HalDisplay.cpp
• src/HalDisplay.h

📜 Recent review details

🧰 Additional context used

📓 Path-based instructions (4)

src/Hal*.{cpp,h}

📄 CodeRabbit inference engine (CLAUDE.md)

When the firmware adds a new method to a HAL class, add a matching stub to the corresponding Hal*.cpp/.h file in the simulator to keep the same public surface or the firmware will not link

Files:

• src/HalDisplay.h
• src/HalDisplay.cpp

src/**/*.{cpp,h}

📄 CodeRabbit inference engine (CLAUDE.md)

Do not call SDL render functions from anywhere except presentIfNeeded in simulator_main on the main thread; keep all SDL calls on the main thread (required for macOS compatibility)

Files:

• src/HalDisplay.h
• src/HalDisplay.cpp

src/*.h

📄 CodeRabbit inference engine (CLAUDE.md)

When adding a new Arduino/ESP-IDF symbol, add the minimum stub to the corresponding header in src/ matching the upstream signature and returning a sensible default

Files:

• src/HalDisplay.h

src/HalDisplay.cpp

📄 CodeRabbit inference engine (CLAUDE.md)

src/HalDisplay.cpp: When changing orientation rotation logic, update both the firmware renderer (90 CCW rotation for Portrait) and the simulator's SDL_RenderCopyEx undoing logic with matching dst rect and centre-offset calculations
Set SDL_HINT_RENDER_SCALE_QUALITY=1 before SDL_CreateTexture, plus use SDL_WINDOW_ALLOW_HIGHDPI and SDL_RenderSetLogicalSize to prevent Bayer-dithered grays from rendering as harsh black/white stripes on Retina displays

Files:

• src/HalDisplay.cpp

🔇 Additional comments (3)

src/HalDisplay.h (1)

70-75: LGTM!

src/HalDisplay.cpp (2)

54-57: 🎯 Functional Correctness

No stride mismatch here. DISPLAY_WIDTH is 792/800, so each scanline is byte-aligned and getBit() uses the same row layout as the strip writes.

			> Likely an incorrect or invalid review comment.

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351-353: 🎯 Functional Correctness

No action needed for displayGrayBuffer()
It intentionally composes from grayscalePreviewState; the grayscale buffer is captured earlier through the copy/strip helpers.

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📝 Walkthrough

Walkthrough

Adds a GrayscalePreviewState in HalDisplay.cpp holding base/LSB/MSB plane buffers with validity flags, plus compositor helpers. refreshDisplay now snapshots the BW framebuffer through these helpers. Grayscale HAL methods are implemented to feed and compose the preview; supportsStripGrayscale() now returns true.

Changes

Grayscale Preview Pipeline

Layer / File(s)	Summary
GrayscalePreviewState and compositor helpers src/HalDisplay.cpp	Adds #include <array>, defines anonymous-namespace GrayscalePreviewState with base/LSB/MSB buffers and validity flags, and implements argbGray, getBit, renderBwPixels, plane snapshot/clear/copy, and composeGrayscalePreview.
HalDisplay method wiring and refreshDisplay integration src/HalDisplay.cpp, src/HalDisplay.h	refreshDisplay replaces the inline pixel loop with a base snapshot and renderBwPixels call. displayGrayBuffer, writeGrayscalePlaneStrip, and supportsStripGrayscale are implemented to feed and compose the preview state. Header comment updated to document intentional strip support.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly matches the main change: adding grayscale and strip rendering support in the simulator.
Description check	✅ Passed	The description is related to the changeset and accurately frames the grayscale fidelity and OOM-testing improvements.
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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Warning

⚠️ This pull request shows signs of AI-generated slop (phantom_api). It has been flagged by CodeRabbit slop detection and should be reviewed carefully.