6c3a615fac
## Summary
- Add embedded image support to EPUB rendering with JPEG and PNG
decoders
- Implement pixel caching system to cache decoded/dithered images to SD
card for faster re-rendering
- Add 4-level grayscale support for display
## Changes
### New Image Rendering System
- Add `ImageBlock` class to represent an image with its cached path and
display dimensions
- Add `PageImage` class as a new `PageElement` type for images on pages
- Add `ImageToFramebufferDecoder` interface for format-specific image
decoders
- Add `JpegToFramebufferConverter` - JPEG decoder with Bayer dithering
and scaling
- Add `PngToFramebufferConverter` - PNG decoder with Bayer dithering and
scaling
- Add `ImageDecoderFactory` to select appropriate decoder based on file
extension
- Add `getRenderMode()` to GfxRenderer for grayscale render mode queries
### Dithering and Grayscale
- Implement 4x4 Bayer ordered dithering for 4-level grayscale output
- Stateless algorithm works correctly with MCU block decoding
- Handles scaling without artifacts
- Add grayscale render mode support (BW, GRAYSCALE_LSB, GRAYSCALE_MSB)
- Image decoders and cache renderer respect current render mode
- Enables proper 4-level e-ink grayscale when anti-aliasing is enabled
### Pixel Caching
- Cache decoded/dithered images to `.pxc` files on SD card
- Cache format: 2-bit packed pixels (4 pixels per byte) with
width/height header
- On subsequent renders, load directly from cache instead of re-decoding
- Cache renderer supports grayscale render modes for multi-pass
rendering
- Significantly improves page navigation speed for image-heavy EPUBs
### HTML Parser Integration
- Update `ChapterHtmlSlimParser` to process `<img>` tags and extract
images from EPUB
- Resolve relative image paths within EPUB ZIP structure
- Extract images to cache directory before decoding
- Create `PageImage` elements with proper scaling to fit viewport
- Fall back to alt text display if image processing fails
### Build Configuration
- Add `PNG_MAX_BUFFERED_PIXELS=6402` to support up to 800px wide images
### Test Script
- Generate test EPUBs with annotated JPEG and PNG images
- Test cases cover: grayscale (4 levels), centering, scaling, cache
performance
## Test plan
- [x] Open EPUB with JPEG images - verify images display with proper
grayscale
- [x] Open EPUB with PNG images - verify images display correctly and no
crash
- [x] Navigate away from image page and back - verify faster load from
cache
- [x] Verify grayscale tones render correctly (not just black/white
dithering)
- [x] Verify large images are scaled down to fit screen
- [x] Verify images are centered horizontally
- [x] Verify page serialization/deserialization works with images
- [x] Verify images rendered in landscape mode
## Test Results
[png](https://photos.app.goo.gl/5zFUb8xA8db3dPd19)
[jpeg](https://photos.app.goo.gl/SwtwaL2DSQwKybhw7)
---
### AI Usage
Did you use AI tools to help write this code? _**< YES >**_
---------
Co-authored-by: Matthías Páll Gissurarson <mpg@mpg.is>
Co-authored-by: Dave Allie <dave@daveallie.com>
91 lines
2.4 KiB
INI
91 lines
2.4 KiB
INI
[platformio]
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default_envs = default
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[crosspoint]
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version = 1.0.0
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[base]
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platform = espressif32 @ 6.12.0
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board = esp32-c3-devkitm-1
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framework = arduino
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monitor_speed = 115200
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upload_speed = 921600
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check_tool = cppcheck
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check_flags = --enable=all --suppress=missingIncludeSystem --suppress=unusedFunction --suppress=unmatchedSuppression --suppress=*:*/.pio/* --inline-suppr
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check_skip_packages = yes
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board_upload.flash_size = 16MB
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board_upload.maximum_size = 16777216
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board_upload.offset_address = 0x10000
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build_flags =
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-DARDUINO_USB_MODE=1
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-DARDUINO_USB_CDC_ON_BOOT=1
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-DMINIZ_NO_ZLIB_COMPATIBLE_NAMES=1
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-DEINK_DISPLAY_SINGLE_BUFFER_MODE=1
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-DDISABLE_FS_H_WARNING=1
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# https://libexpat.github.io/doc/api/latest/#XML_GE
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-DXML_GE=0
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-DXML_CONTEXT_BYTES=1024
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-std=gnu++2a
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# Enable UTF-8 long file names in SdFat
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-DUSE_UTF8_LONG_NAMES=1
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# Increase PNG scanline buffer to support up to 800px wide images
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# Default is (320*4+1)*2=2562, we need more for larger images
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-DPNG_MAX_BUFFERED_PIXELS=6402
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build_unflags =
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-std=gnu++11
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; Board configuration
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board_build.flash_mode = dio
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board_build.flash_size = 16MB
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board_build.partitions = partitions.csv
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extra_scripts =
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pre:scripts/build_html.py
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; Libraries
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lib_deps =
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BatteryMonitor=symlink://open-x4-sdk/libs/hardware/BatteryMonitor
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InputManager=symlink://open-x4-sdk/libs/hardware/InputManager
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EInkDisplay=symlink://open-x4-sdk/libs/display/EInkDisplay
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SDCardManager=symlink://open-x4-sdk/libs/hardware/SDCardManager
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bblanchon/ArduinoJson @ 7.4.2
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ricmoo/QRCode @ 0.0.1
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bitbank2/PNGdec @ ^1.0.0
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links2004/WebSockets @ 2.7.3
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[env:default]
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extends = base
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build_flags =
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${base.build_flags}
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-DCROSSPOINT_VERSION=\"${crosspoint.version}-dev\"
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-DENABLE_SERIAL_LOG
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-DLOG_LEVEL=2 ; Set log level to debug for development builds
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[env:gh_release]
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extends = base
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build_flags =
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${base.build_flags}
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-DCROSSPOINT_VERSION=\"${crosspoint.version}\"
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-DENABLE_SERIAL_LOG
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-DLOG_LEVEL=0 ; Set log level to error for release builds
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[env:gh_release_rc]
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extends = base
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build_flags =
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${base.build_flags}
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-DCROSSPOINT_VERSION=\"${crosspoint.version}-rc+${sysenv.CROSSPOINT_RC_HASH}\"
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-DENABLE_SERIAL_LOG
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-DLOG_LEVEL=1 ; Set log level to info for release candidate builds
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[env:slim]
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extends = base
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build_flags =
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${base.build_flags}
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-DCROSSPOINT_VERSION=\"${crosspoint.version}-slim\"
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; serial output is disabled in slim builds to save space
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-UENABLE_SERIAL_LOG
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