jpirnay 40e4c96906 refactor: replace picojpeg with JPEGDEC for cover art conversion (#1517) ...

## Summary

- Removes the vendored `picojpeg` library and rewrites
`JpegToBmpConverter` to use the already-present `JPEGDEC` (bitbank2)
dependency
- Eliminates the redundancy of having two JPEG decoders in the firmware
- All BMP output (headers, fixed-point scaling, Atkinson/Floyd-Steinberg
dithering) is identical to before — cached cover BMPs are unaffected

## Size impact

| | Before | After | Delta |
|---|---|---|---|
| Flash | 5,754,089 bytes (87.8%) | 5,744,777 bytes (87.7%) | **−9,312
bytes** |
| RAM | 95,212 bytes (29.1%) | 92,852 bytes (28.3%) | **−2,360 bytes** |

## Implementation notes

- `bmpDrawCallback` receives MCU-sized blocks from JPEGDEC (up to 16
rows × MCU-width), accumulates them into a pre-allocated `mcuBuf`, and
applies the same scaling + dithering logic once each MCU row is complete
- File I/O uses a file-scope static `FsFile*` (safe in single-threaded
embedded context) via JPEGDEC's open/read/seek callbacks — same pattern
as `JpegToFramebufferConverter`
- Added a 52 KB free-heap guard before allocating the JPEGDEC object
(~17 KB)
- `lib/picojpeg/` deleted (2,087 lines of C removed)

## Test plan

- [ ] Build compiles without warnings
- [ ] Cover art BMP cache regenerates correctly for EPUB books
- [ ] Home screen thumbnails (1-bit BMP path) render correctly
- [ ] Custom-size thumbnails (`jpegFileToBmpStreamWithSize`) render
correctly

🤖 Generated with [Claude Code](https://claude.com/claude-code)

2026-04-15 23:20:24 -05:00

..

JpegToBmpConverter.cpp

refactor: replace picojpeg with JPEGDEC for cover art conversion (#1517)

2026-04-15 23:20:24 -05:00

JpegToBmpConverter.h

refactor: replace picojpeg with JPEGDEC for cover art conversion (#1517)

2026-04-15 23:20:24 -05:00