Adjust the characters-per-page value and automatically calculate it based on the page count of the physical edition on device

[bergsoren]

Hi!

I really enjoy using the stable page numbers feature.

Unfortunately the process of changing the stable page count mid reading is pretty complicated:

1. Optimize the epub again through inky, knowing the character-per-page value resulting in a given stable page count
2. Finding the original epubs folder and the newly optimized epubs folder on device as the hashes are not easily readable
3. Copying the progress.bin, progress_percent.bin, reader_settings, dictionary_history.txt and stats_v5 files to the new epubs folder
4. Deleting the old folder

Especially as I like to exactly match the stable page count to a specific physical edition of the book, it can get quite cumbersome to do this process multiple times.

A feature that lets me

1. change the default 1500 character per page count on device and
2. similar to https://github.com/Craftwork2720/koreader-patches/tree/main#2-physical-page-count--match-page-numbers-to-a-physical-edition input the physical editions page count to automatically calculate the characters-per-page value, would be amazing!

Thank you for your work, I really enjoy using CrossInk!

[uxjulia]

I can't allow changing the character count on device because it requires inky to do the calculations for the entire book and generate the json file that the firmware uses to determine what page you are in relation to the total stable page numbers. That json file is then bundled into the .epub file which is then read back inside the firmware.

Also you actually don't need to do steps 2-4 when you re-optimize. If your original filename was "some book.epub" and you reoptimize, just replace the file with the newer one with the same filename. To the firmware, it's the same book. You may or may not have to delete the book's cache if the stable page count doesn't update, but that doesn't delete progress or stats or anything. It just removes generated files and regenerates it.

If you figure out the book's physical pages beforehand and the characters per page, you won't need to re-optimize it midway.

[bergsoren]

Thanks for the quick reply and the info about steps 2-4, that helps a lot!

What about a feature for inky then to choose wether to input the characters per page value directly or just the physical editions page count for it to automatically calculate the characters per page? That would make the trial and error of finding the characters per page that results in an exact page count obsolete.

Does the web version of inky match the built in optimizer when using the file transfer feature? I only used the latter

[uxjulia]

Thanks for the quick reply and the info about steps 2-4, that helps a lot!

What about a feature for inky then to choose wether to input the characters per page value directly or just the physical editions page count for it to automatically calculate the characters per page? That would make the trial and error of finding the characters per page that results in an exact page count obsolete.

I'll think about this, I've got some other priorities ahead of inky enhancements right now, but I'll put it on my backlog.

Does the web version of inky match the built in optimizer when using the file transfer feature? I only used the latter

And yes, the two optimizers should match in what they do, though they're using different engines to run the optimizer, so results might differ slightly (I think moreso when it comes to how it handles images). The built-in one is using the browser (so javascript) while Inky is using python running on a server.

[bergsoren]

Thank you!

In the meantime, I figured out my problem:
The built-in file browser through crosspoint.local automatically renames the hash folders when renaming the epub and forbids to have another epub be the same name as a previously used epub’s name. Therefore the process you described is not possible through the wireless transfer.

This is further complicated as this file browser has no option to rename folders and moving multiple files at once from one folder to another is not possible.

So the necessary steps to change the stable page numbers is:

1. Reoptimize the epub through inky (I built a small python script that changes the totalReferencePages and charactersPerReferencePage of an already optimized epub with the physical edition’s page count as input)
2. Upload this epub to crossink through crosspoint.local
3. Cancel the file transfer process and open the epub for the hash folder to be created and restart the file transfer process
4. Delete the old epub (the stats files should remain, but backup your files before just in case)
5. Find both the new and old epub’s hash folder and move the stats files from the old to the new folder one by one

Is there an easier way to achieve this wirelessly without having to remove the sd card?

[uxjulia]

You could save yourself all that trouble by just deleting the original epub first. Reader settings, reading stats, and progress don't get deleted when you delete the epub (the firmware will remove some cache files and explicitly preserve reader settings, reading stats, and progress). So once the first epub is deleted, there won't be a filename conflict when you upload the newly optimized file with the same filename.

So steps would be:

1. Delete old epub
2. Upload newer optimized epub (with exact same filename to the exact same location).

You can test this with a random book first just to be sure, but looking at the code, this should work.