[Bug] Chinese epub vertical documents cannot be read normally

[Kao953]

Describe the bug

When using Readium to read Chinese books in vertical epub format or using the vertical text function, there is no problem with flipping chapters left and right, but when flipping to the next page up and down, it will be forced to jump to the next chapter and cannot flip normally.

a126af70-1411-48b3-ac70-e085b8ee8681.mp4

How to reproduce?

1. Open TestApp
2. Click chinese vertical text mode epub file
3. flip page

Readium version

v2.4.0

Android API version

33

Additional context

No response

[danielweck]

Hello, are you able/allowed to share a Chinese EPUB so we can run some tests? I am a Thorium developer, I would like to make sure that our implementation is correct for Chinese (we recently validated our Japanese support). Thank you!

[Kao953]

Sorry for the late response. The following link is valid until August 1st.
https://1drv.ms/u/s!Am0spwgeMVybjp1o9QvXEq076srMYw