What ePub page/position calculation methods are there?

[mattcurtis]

Originally Posted by PeterT

ADE page numbers are constant, regardless of things like font sizes / screen size etc. Roughly speaking, as others have said, they are based on a 1024 character chunk of the text; each 1k is a page.

Here's what confuses me about that: how does that account for paragraph margin, font-size, etc? I mean, if the font size is large enough, how will the pages number ever map correctly to what the user is seeing? Or do page numbers account for swathes of text? I can't seem to find information that explains it thoroughly, or at least has code that implements it.

[JSWolf]

Originally Posted by mattcurtis

Here's what confuses me about that: how does that account for paragraph margin, font-size, etc? I mean, if the font size is large enough, how will the pages number ever map correctly to what the user is seeing? Or do page numbers account for swathes of text? I can't seem to find information that explains it thoroughly, or at least has code that implements it.

I've already told you that the Count Pages Calibre plug-in has the code to do the ADE page count. You groaned that it's in Python. Did you forget that fast? You can look there and see how it's calculated.

ADE's method of pages uses a count of the text in the XML files. It does not matter what the CSS tells the XML how to display or what the user has set the font size to. The XML is a set file. Nothing the CSS does changes that. How it displays does not change the size of the file.

[mattcurtis]

Originally Posted by JSWolf

I've already told you that the Count Pages Calibre plug-in has the code to do the ADE page count. You groaned that it's in Python. Did you forget that fast? You can look there and see how it's calculated.

ADE's method of pages uses a count of the text in the XML files. It does not matter what the CSS tells the XML how to display or what the user has set the font size to. The XML is a set file. Nothing the CSS does changes that. How it displays does not change the size of the file.

I'm still looking at its code, actually - it's been helpful, even though my Python sucks. I was asking for more information about the methodology so I can understand how to translate that into code that code into Obj-C/JavaScript (what I'm working with).

Secondly, if I'm not working with a compressed ePub, but an extracted one, does the same 1024 bytes apply?

[mattcurtis]

Finally found something that explains this in detail: http://bookclubs.barnesandnoble.com/...ng/td-p/691602

I think it's starting to map itself together in my head (my code, at least) I'm not as confused anymore. Thanks for the help.

[JSWolf]

Originally Posted by mattcurtis

Secondly, if I'm not working with a compressed ePub, but an extracted one, does the same 1024 bytes apply?

There is no such thing as an extracted ePub. ePub is a ZIP container. So you work with the ePub as it is for the page count. You don't count things like images, CSS, OPF, etc. You only count the files in the spine in the OPF. You count the compressed bytes to get 1024 and then whatever that becomes when uncompressed to is your page.

[Jellby]

Originally Posted by PeterT

Actually I wold have thought that with the ADE style of page numbering, no degree of changes to the CSS would affect the page number. After all that is the whole idea behind the synthetic numbering.

Not if the CSS is in a separate file, but every change in the HTML files can change the page numbering, including simply adding spaces or comments in the code. Even changing the zip compression level does change the page numbering!

[Jellby]

Originally Posted by mattcurtis

Finally found something that explains this in detail: http://bookclubs.barnesandnoble.com/...ng/td-p/691602.

There is a slight disagreement there. That page says:

"The first page will be 1212 characters long, and the second will be 1213 long."

While our wiki (which was copied from what Adobe once had online, I believe), says:

"... round the number of characters per page up and let the last “page” contain less characters than the rest."
which would mean that the first page is 1213 characters and the second 1212.

[mattcurtis]

Originally Posted by Jellby

There is a slight disagreement there. That page says:

"The first page will be 1212 characters long, and the second will be 1213 long."

While our wiki (which was copied from what Adobe once had online, I believe), says:

"... round the number of characters per page up and let the last “page” contain less characters than the rest."
which would mean that the first page is 1212 characters and the second 1212.

That's what I thought, thanks. I'm not sure why my puddy-brain wasn't getting ADE pages.