I added vertical text (tategumi) support to KOReader fork
I'm a Japanese user who jailbreaks Kindle to read Japanese novels with KOReader. I wanted proper vertical text (縦書き) support, but existing Lua-only patches felt like workarounds to me. I checked upstream PRs but it didn't seem like something they'd take on.
So I forked KOReader and implemented vertical-rl rendering at the engine level (crengine), rather than patching around it in Lua. Existing KOReader features should all still work — I just added the vertical text engine on top.
What works:
- Japanese EPUBs with writing-mode: vertical-rl
- Ruby annotations (ルビ)
- Character rotation (ー、…、括弧類 etc.)
- Text selection and highlights
There may still be bugs. If you're in a similar situation — jailbroken Kindle or Kobo, wanting to read Japanese novels vertically — feel free to try it.
https://github.com/m-tky/koreader-tategumi
Big thanks to the KOReader developers for building such an extensible platform. None of this would have been possible without their work.
