## 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)
## Summary
Fix https://github.com/crosspoint-reader/crosspoint-reader/issues/1137
Introducing `HalFile`, a thin wrapper around `FsFile` that uses a global
mutex to protect file operations.
To test this PR, place the code below somewhere in the code base (I
placed it in `onGoToRecentBooks`)
```cpp
static auto testTask = [](void* param) {
for (int i = 0; i < 10; i++) {
String json = Storage.readFile("/.crosspoint/settings.json");
LOG_DBG("TEST_TASK", "Read settings.json, bytes read: %u", json.length());
}
vTaskDelete(nullptr);
};
xTaskCreate(testTask, "test0", 8192, nullptr, 1, nullptr);
xTaskCreate(testTask, "test1", 8192, nullptr, 1, nullptr);
xTaskCreate(testTask, "test2", 8192, nullptr, 1, nullptr);
xTaskCreate(testTask, "test3", 8192, nullptr, 1, nullptr);
delay(1000);
```
It will reliably lead to crash on `master`, but will function correctly
with this PR.
A macro renaming trick is used to avoid changing too many downstream
code files.
---
### AI Usage
While CrossPoint doesn't have restrictions on AI tools in contributing,
please be transparent about their usage as it
helps set the right context for reviewers.
Did you use AI tools to help write this code? **PARTIALLY**, only to
help with tedious copy-paste tasks
---------
Co-authored-by: Zach Nelson <zach@zdnelson.com>
## Summary
* **What is the goal of this PR?** (e.g., Fixes a bug in the user
authentication module,
Display the book cover image in the **"Continue Reading"** card on the
home screen, with fast navigation using framebuffer caching.
* **What changes are included?**
- Display book cover image in the "Continue Reading" card on home screen
- Load cover from cached BMP (same as sleep screen cover)
- Add framebuffer store/restore functions (`copyStoredBwBuffer`,
`freeStoredBwBuffer`) for fast navigation after initial render
- Fix `drawBitmap` scaling bug: apply scale to offset only, not to base
coordinates
- Add white text boxes behind title/author/continue reading label for
readability on cover
- Support both EPUB and XTC file cover images
- Increase HomeActivity task stack size from 2048 to 4096 for cover
image rendering
## Additional Context
* Add any other information that might be helpful for the reviewer
(e.g., performance implications, potential risks, specific areas to
focus on).
- Performance: First render loads cover from SD card (~800ms),
subsequent navigation uses cached framebuffer (~instant)
- Memory: Framebuffer cache uses ~48KB (6 chunks × 8KB) while on home
screen, freed on exit
- Fallback: If cover image is not available, falls back to standard
text-only display
- The `drawBitmap` fix corrects a bug where screenY = (y + offset) scale
was incorrectly scaling the base coordinates. Now correctly uses screenY
= y + (offset scale)
## Summary
* Swap to updated SDCardManager which uses SdFat
* Add exFAT support
* Swap to using FsFile everywhere
* Use newly exposed `SdMan` macro to get to static instance of
SDCardManager
* Move a bunch of FsHelpers up to SDCardManager
## Summary
* **What is the goal of this PR?**
Replace simple threshold-based grayscale quantization with ordered
dithering using a 4x4 Bayer matrix. This eliminates color banding
artifacts and produces smoother gradients on e-ink display.
* **What changes are included?**
- Add 4x4 Bayer dithering matrix for 16-level threshold patterns
- Modify `grayscaleTo2Bit()` function to accept pixel coordinates and
apply position-based dithering
- Replace simple `grayscale >> 6` threshold with ordered dithering
algorithm that produces smoother gradients
## Additional Context
* Bayer matrix approach: The 4x4 Bayer matrix creates a repeating
pattern that distributes quantization error spatially, effectively
simulating 16 levels of gray using only 4 actual color levels (black,
dark gray, light gray, white).
* Cache invalidation: Existing cached `cover.bmp` files will need to be
deleted to see the improved rendering, as the converter only runs when
the cache is missing.
## Summary
- Add basic JPG image support
- Map JPG back to 2-bit BMP output
- Can be used to later render the BMP file from disk or directly pass to
output if wanted
- Give the 3 passes over the data needed to render grayscale content,
putting it on disk is preferred to outputting it multiple times
## Additional Context
- WIP, looking forward to BMP support from
https://github.com/daveallie/crosspoint-reader/pull/16
- Addresses some of #11
Zach Nelson