# Port PR #1055: Byte-level framebuffer writes

**Date:** 2026-02-21
**Task:** Port upstream PR #1055 (jpirnay) into the mod, including coderabbit review nitpick.

## Changes made

### `lib/GfxRenderer/GfxRenderer.h`
- Added two private method declarations: `fillPhysicalHSpanByte` (patterned byte-level span writer) and `fillPhysicalHSpan` (solid-fill wrapper).

### `lib/GfxRenderer/GfxRenderer.cpp`
- Added `#include <cstring>` for `memset`.
- Implemented `fillPhysicalHSpanByte`: bounds-clamped byte-level span writer with MSB-first bit packing, partial-byte masking at edges, and `memset` for aligned middle.
- Implemented `fillPhysicalHSpan`: thin wrapper mapping `state` bool to `0x00`/`0xFF` pattern byte.
- **`drawLine`**: Replaced per-pixel loops for axis-aligned lines with orientation-aware `fillPhysicalHSpan` calls (vertical lines in Portrait, horizontal lines in Landscape).
- **`fillRect`**: Replaced per-row `drawLine` loop with orientation-specific byte-level fast paths for all 4 orientations.
- **`fillRectDither`**: Replaced per-pixel `drawPixelDither` loops for DarkGray/LightGray with orientation-aware `fillPhysicalHSpanByte` using pre-computed byte patterns.
- **`fillPolygon`** (coderabbit nitpick): Added `fillPhysicalHSpan` fast path for Landscape orientations in the scanline inner loop.

### `mod/prs/MERGED.md`
- Appended PR #1055 entry with full documentation.

## Differences from upstream
- `fillPolygon` landscape optimization (from coderabbit review nitpick) was applied as a mod enhancement.

## Follow-up items
- None. Build verified successful.