30d8a8d011
## Summary **What is the goal of this PR?** Implement support for footnotes in epub files. It is based on #553, but simplified — removed the parts which complicated the code and burden the CPU/RAM. This version supports basic footnotes and lets the user jump from location to location inside the epub. **What changes are included?** - `FootnoteEntry` struct — A small POD struct (number[24], href[64]) shared between parser, page storage, and UI. - Parser: `<a href>` detection (`ChapterHtmlSlimParser`) — During a single parsing pass, internal epub links are detected and collected as footnotes. The link text is underlined to hint navigability. Bracket/whitespace normalization is applied to the display label (e.g. [1] → 1). - Footnote-to-page assignment (`ChapterHtmlSlimParser`, `Page`) — Footnotes are attached to the exact page where their anchor word appears, tracked via a cumulative word counter during layout, surviving paragraph splits and the 750-word mid-paragraph safety flush. - Page serialization (`Page`, `Section`) — Footnotes are serialized/deserialized per page (max 16 per page). Section cache version bumped to 14 to force a clean rebuild. - Href → spine resolution (`Epub`) — `resolveHrefToSpineIndex()` maps an href (e.g. `chapter2.xhtml#note1`) to its spine index by filename matching. - Footnotes menu + activity (`EpubReaderMenuActivity`, `EpubReaderFootnotesActivity`) — A new "Footnotes" entry in the reader menu lists all footnote links found on the current page. The user scrolls and selects to navigate. - Navigate & restore (`EpubReaderActivity`) — `navigateToHref()` saves the current spine index and page number, then jumps to the target. The Back button restores the saved position when the user is done reading the footnote. **Additional Context** **What was removed vs #553:** virtual spine items (`addVirtualSpineItem`, `isVirtualSpineItem`), two-pass parsing, `<aside>` content extraction to temp HTML files, `<p class="note">` paragraph note extraction, `replaceHtmlEntities` (master already has `lookupHtmlEntity`), `footnotePages` / `buildFilteredChapterList`, `noterefCallback` / `Noteref` struct, and the stack size increase from 8 KB to 24 KB (not needed without two-pass parsing and virtual file I/O on the render task). **Performance:** Single-pass parsing. No new heap allocations in the hot path — footnote text is collected into fixed stack buffers (char[24], char[64]). Active runtime memory is ~2.8 KB worst-case (one page × 16 footnotes × 88 bytes, mirrored in `currentPageFootnotes`). Flash usage is unchanged at 97.4%; RAM stays at 31%. **Known limitations:** When clicking a footnote, it jumps to the start of the HTML file instead of the specific anchor. This could be problematic for books that don't have separate files for each footnote. (no element-id-to-page mapping yet - will be another PR soon). --- ### AI Usage Did you use AI tools to help write this code? _**< PARTIALLY>**_ Claude Opus 4.6 was used to do most of the migration, I checked manually its work, and fixed some stuff, but I haven't review all the changes yet, so feedback is welcomed. --------- Co-authored-by: Arthur Tazhitdinov <lisnake@gmail.com>
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