Thread: Touch When turning off and on sometimes the page of the book has moved backwards?
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Old 07-24-2014, 11:07 AM   #8
davidfor
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Posts: 24,905
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Join Date: Jul 2011
Location: Sydney, Australia
Device: Kobo:Touch,Glo, AuraH2O, GloHD,AuraONE, ClaraHD, Libra H2O; tolinoepos
Quote:
Originally Posted by MacEachaidh View Post
Hi topcat,
I've got a Touch and Aura HD. I've seen this behaviour on the Touch from the day I first got it, so I doubt it's a issue of database corruption. In any case, at least twice in its life I've done hard resets and reinstalled the firmware, and the behaviour has continued unchecked. It happens on my Aura HD as well, but far less frequently, and I think that's a clue.

What it seems to come down to, in my opinion, is that the Digital Editions logical page and the Kobo display page are often (usually?) different lengths. The difference is affected by font size, line spacing etc. If you switch on the ADE page numbers, you'll see they usually don't line up.

It seems that when the Kobo goes to sleep (or off) and then fires up again, if the display page you were on coincides with the top of an ADE logical page, then the Kobo opens up to the display page you were on. But if the start of the specific logical page you were on actually falls one or even two display pages back from where you were, then that's where the Kobo will open up.

That's how it seems to work for me, anyway. (And just to clarify, I'm only reading ePub books, not kepubs, which I believe use a different display enginge so may get different behaviour in this respect.)
Firstly, the bottom of the screen page number is the page number for the first character on the screen. That means the in-margin page number is usually one higher than at the bottom of the screen. And if you use a small font, there can be two or three page numbers in the margin. I don't usually show the in-margin page numbers, but I have never seen the two number not following these rules.

For the reading position, the device does not store the page number. It stores a reference to the current file within the epub, and a pointer to first character on the screen. An example of this is:

Code:
OEBPS/Text/Section0001.html#point(/1/4/6/2/1:126)
The set of numbers in the "point" are a count of the number of tags at each level of nesting within the file. The last number is the count within the tag of the character that is first on the screen.The position above is in the middle of bold text within the third paragraph in the chapter.

Note: The tag counts are always even and seem to counting opening and closing tags. I'm not sure what happens with "<br/>" or "<hr/>".

When the book is reopened, it should be reopened to display that character. If nothing has changed in the reading settings, this same character should be the first on the screen. If the reading settings have changed, then it could be elsewhere on the screen. And if that happened, the page number displayed could be one or two less than when the book was closed.

I don't think this is what topcat07 is seeing. But, I could see the rendering getting slightly different results when paging through a book vs opening to a position. And the further into a chapter, the more likely this would be.
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