[arspr]

This discussion comes from KoboTouchExtended driver for Calibre thread

Originally Posted by davidfor

...When the user changes the font, font size, margins or line spacing, you rerender and recalculate the page numbers.

I've just noticed that when full book page numbering is off, Kobo does actually have that behaviour.

Wow!, I do think it's PREEETTY strange and USELESS. I mean, page numbering in a ebook is quite "stupid" as an accurate way of positioning. But it just has two main functions:

• Comparing (in an approximate way) book sizes. More or less like it happens with books in paper. A book with 100 pages is not exactly 10 times shorter than a book with 1000 pages because they will probably have completely different editions. But you can always say that the 100 page book is A LOT shorter.
• Allowing "accurate" (more or less) jumps or references inside the book. If I say "hey, I really liked the passage in page 32 about the hero death", anyone with the same book can easily find it. BUT with the Kobo system you have to say "... in page 32, with this font, this margin and that spacing". Very, very useful, more or less like a square wheel, which can also roll if pushed hard enough.

Nevertheless, this behaviour doesn't seem to be active in Full Book Page Numbering mode (luckily, although I'm not sure).

Originally Posted by davidfor

Yes it is on a low power device. To use per chapter page numbering, you render the current chapter and calculate the numbers. When the user changes the font, font size, margins or line spacing, you rerender and recalculate the page numbers.

To do full page numbering, you need to render the complete book. And re-render each time the settings are changed. For a short book, that will be OK. But, for a long book (think all of Lord of the Rings in one book), that could take some time. And the devices have limited RAM, so t might not even be possible.

Even if the numbering in full book mode went as in the strange Koboish chapter mode, what you say is not necessarily a serious difficulty.

I mean, after the first few tries looking for a comfortable looking, how many times do you change rendering settings in a book? And even if you are making thousands of changes a day because you are really nervous I propose the following method:

• Kobo devices has a beautiful DATABASE, don't they? So till you change something in rendering settings (or even in the book itself), you just need to perform that rendering ONCE and then write down the number of pages each chapter has.
• Of course, on the first run, if the book changes, (or because the weird Koboish numbering method, when you change the reading settings), you need to recalculate those page numbers. And, as you say, it can be really taxing with "The Bible" on Kobo ZX Spectrum model. But I suggest the following solution: can't you make that calculation in the background with your spare resources? I mean, just show a "Calculating pages" text in footer, keep your main CPU resources in making the device responsive to the user inputs without great delays, and then take all the time you need to finish that calculation.
• And because the RAM is also an issue, perform the former process splitting chapters/files in smaller pieces.

Originally Posted by davidfor

Full book page numbering with epubs and the RMSDK is only possible because it calculates the number of pages based on the compressed size of the files. They are independent of the reader settings.

I didn't know that was the process.

But nevertheless I think it's a clever, easy and accurate enough method. What problem does it actually have? Because the page numbering is made on the "amount of letters", (that's the size in disguise, with the added distortion of the compression process and the fact that a lot of those letters are invisible code tags), the only trouble it has is that "pages" with light and fast dialogues are going to be much longer than dense descriptions. And? I don't need an extremely accurate reference system, just a RELIABLE one.

So please, Kobo, as we say in a Spanish idiom: Do not try to fix what currently works.