Current reading position (currentLocationCfi) is not correctly saved in at some screen resolutions about epub.js

[fchasen]

Updated EPUBJS.Renderer.prototype.isElementVisible

Thanks!

[panurge-ws]

I'm sorry, but after running some tests, also the solution suggested above is not working.
With left <= width, if we have a page with an element that ends exactly at the end of the page/column, the first visible becomes the fist in the next page....

The problem occurs within an iPhone screen: it seems with small page (spreadWith) width it fails to catch the right first visible element. I'm looking for some other solutions.
(Thanks for your work)

[bielskij]

Hi,
I've noticed the same issue on some books rendered on small screens.

The issue is reproductible with a google chrome browser with reduced size of div where epubjs renders a book.

I've found that CFI attached to the pageMap of chapter contains incorrect endOffset value in case of callapsed paragraph/span. The CFI points to the last word on previous page, so finally the function generateRangeFromCfi() generates range that left position is smaller than pageSize. Function getPageNumberByRect() called by gotoCfi() with range returned from generateRangeFromCfi() using extra function Math.floor() designates incorrect page number (it points to the previous one).

I'm not able to provide the best solution but I think that the process of generating page CFI should be fixed - it should return offset from the first word on the next page, not offset of the last word on previous page as is now.

[bielskij]

Hi,

I've deeper investigated the issue and I've already got a simple solution. The issue was related to bad working CFI generator mechanism for DOM element. It uses string.indexOf method to split text into words by space character. As there could be other characters that can break the line, they should be proprly handled.

You can find fix in my forked branch, commit 287cbcd.

[fchasen]

Fix is now in master, thanks again @bielskij