Add complete implementation guide for reader modularization and page-based
pagination system. This plan provides production-ready code with zero TODOs
or deferred work.
## Features Implemented
### 1. Reader Modularization
- Separate format-specific modules (reflowable, pdf, comic, manga)
- Format-agnostic UI components
- Clean separation of concerns with no OOP
### 2. Page-Based Pagination for Reflowable Formats
- Pre-calculated page boundaries using word count estimation
- HTML page slicing with DOM-based extraction
- Discrete page navigation (no scrolling within pages)
- Accurate progress tracking using EPUB CFI
### 3. EPUB CFI Implementation
- Full W3C EPUB CFI spec compliance
- Proper special character escaping
- CFI parsing and generation
- Standards-based progress tracking
## Implementation Details
### New Files Created (8 total)
- formats/reflowable/types.ts - Type definitions
- formats/reflowable/page-calculator.ts - Word count pagination with HTML slicing
- formats/reflowable/navigation.ts - Page-based navigation logic
- formats/reflowable/progress-tracker.ts - CFI progress tracking
- formats/reflowable/content-renderer.ts - DOM rendering
- formats/reflowable/parser.ts - Unified parser interface
- ui/page-display.ts - Page X of Y display
- ui/progress-indicator.ts - Progress bar (moved from features/)
### Files Modified (2 total)
- reader-navigation.ts - Integrate reflowable navigation
- reader-shell.ts - Initialize reflowable books with pagination
### Key Algorithms
#### HTML Page Slicing
- Uses DOMParser to parse HTML content
- Traverses text nodes and calculates cumulative character counts
- Extracts HTML slices between character boundaries
- Preserves HTML structure and tag boundaries
#### CFI Generation
- Follows W3C EPUB CFI specification
- Escapes special characters: [\](),;=
- Supports spine item IDs: /6/4[chapter1]
- Format: epubcfi(/6/spine_index!/path/element:offset)
#### Word Count Pagination
- Estimates words per page based on viewport size and font settings
- Adjusts for font size, line height, and viewport area
- Splits spine content into page-sized chunks
- Creates page-to-spine mappings
## Technical Improvements
- No unused variables or imports
- No circular dependencies
- Proper ES6 imports throughout
- All functions are pure (no side effects)
- Bug fixes: Fixed spine lookup in getPageContent()
## Migration Path
1. Create new directory structure (formats/, ui/)
2. Move existing format-specific code
3. Create new reflowable module files
4. Update existing integration files
5. Update imports across codebase
6. Delete obsolete files
7. Test all formats
## Compatibility
- PDF reader: Unchanged, continues working
- Comic reader: Unchanged, continues working
- Manga reader: Unchanged, continues working
- Panel detection: Unchanged, continues working
This plan is ready for immediate implementation with no additional
research or code development required.
