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## Summary * **What is the goal of this PR?** Add support for XTC (XTeink X4 native) ebook format, which contains pre-rendered 480x800 1-bit bitmap pages optimized for e-ink displays. * **What changes are included?** - New `lib/Xtc/` library with XtcParser for reading XTC files - XtcReaderActivity for displaying XTC pages on e-ink display - XTC file detection in FileSelectionActivity - Cover BMP generation from first XTC page - Correct XTG page header structure (22 bytes) and bit polarity handling ## Additional Context - XTC files contain pre-rendered bitmap pages with embedded status bar (page numbers, progress %) - XTG page header: 22 bytes (magic + dimensions + reserved fields + bitmap size) - Bit polarity: 0 = black, 1 = white - No runtime text rendering needed - pages display directly on e-ink - Faster page display compared to EPUB since no parsing/rendering required - Memory efficient: loads one page at a time (48KB per page) - Tested with XTC files generated from https://x4converter.rho.sh/ - Verified correct page alignment and color rendering - Please report any issues if you test with XTC files from other sources. --------- Co-authored-by: Dave Allie <dave@daveallie.com>
# XTC/XTCH Library XTC ebook format support for CrossPoint Reader. ## Supported Formats | Format | Extension | Description | |--------|-----------|----------------------------------------------| | XTC | `.xtc` | Container with XTG pages (1-bit monochrome) | | XTCH | `.xtch` | Container with XTH pages (2-bit grayscale) | ## Format Overview XTC/XTCH are container formats designed for ESP32 e-paper displays. They store pre-rendered bitmap pages optimized for the XTeink X4 e-reader (480x800 resolution). ### Container Structure (XTC/XTCH) - 56-byte header with metadata offsets - Optional metadata (title, author, etc.) - Page index table (16 bytes per page) - Page data (XTG or XTH format) ### Page Formats #### XTG (1-bit monochrome) - Row-major storage, 8 pixels per byte - MSB first (bit 7 = leftmost pixel) - 0 = Black, 1 = White #### XTH (2-bit grayscale) - Two bit planes stored sequentially - Column-major order (right to left) - 8 vertical pixels per byte - Grayscale: 0=White, 1=Dark Grey, 2=Light Grey, 3=Black ## Reference Original format info: <https://gist.github.com/CrazyCoder/b125f26d6987c0620058249f59f1327d>