MoonSync: share reading positions between calibre's E-book viewer and Moon+ Reader

[Spagoodlers]

MoonSync: share reading positions between calibre's E-book viewer and Moon+ Reader

Hi all, first-time poster here.

I read on my phone and tablet with Moon+ Reader Pro and manage my library in calibre on my desktop. I'd often add a book in calibre, read a good chunk of it in the viewer, and then open it on my phone later with no idea where I'd left off. MoonSync is a calibre plugin I wrote to fix that.

Moon+ Reader Pro can sync reading positions through Dropbox by keeping a small .po file per book. MoonSync reads and writes those files, so calibre's viewer and Moon+ share one position:

• Open a book in calibre (double-click, View button, recent books, anything) and it starts at your Moon+ position if that one is newer.
• While you read in calibre, your position is saved back for Moon+ every few seconds and when you close the viewer.
• Books you start in calibre can get a new .po file, so they open in the right place in Moon+ too.
• Manual sync for one book, a selection, or everything, in either direction, with a book-by-book report.

Requirements: calibre 6+ (Windows, macOS, Linux), Moon+ Reader Pro with Dropbox position sync turned on, EPUB only. Any folder holding the .po files works, so other sync tools are fine too.

Important: Use the same EPUB file on both sides, ideally by sending it to your device from calibre. Moon+ stores positions as a chapter number plus a character offset, so they only line up when the files match.

Known limitations

• Moon+'s "chapters" don't always match the EPUB's internal files. It also splits at some TOC entries, and the rules aren't documented. The plugin works out the layout per book by checking against Moon+'s own percentage, but it isn't perfect yet.
• You may land up to a page early, because Moon+ saves the top of the screen rather than the line you were reading.
• If a position doesn't fit the book, calibre falls back to Moon+'s percentage (close, not exact) and the plugin won't write to that book's .po file, so it never sends Moon+ to the wrong place.

Download / source: https://github.com/Spagoodlers/moonsync
The README covers setup, settings and troubleshooting.

If you hit a problem, the plugin logs every decision to moonsync.log in calibre's config folder under plugins. Please include the relevant lines with a bug report.

I'd love help from anyone who knows Moon+'s position format or calibre's viewer internals better than I do, especially with the chapter layout detection. Feedback and pull requests are very welcome.

Thanks!