Support to PDF's Optional Content Groups (OCG) in 2024

[rgaiacs]

Hi,

I'm learning languages and I would like to create my own PDF flashcard deck where I would store the answers in an Optional Content Groups (OCG). I would hand write in the PDF, click in a link / button to show the correct answers and verify my answers. Attach is a example. The Optional Content Groups (OCG) works on Evince https://wiki.gnome.org/Apps/Evince and Firefox's built-in PDF viewer.

I have a 2016 Kobo Aura One and it does NOT support Optional Content Groups (OCG).

Does anyone know the Optional Content Groups (OCG) support in 2023 / 2024 devices? Or could you verify using the provided example?

- Kindle Scribe
- Kobo Sage
- Kobo Elipsa 2E
- Onyx Boox Note

[Quoth]

1. The answers are not in English. They should be in BOTH languages. They do display in Ocular on Desktop, but by default forms/javascript is disabled. You can't use a keyboard as an option, which is a strange use of PDF forms. Enabling 'Forms' will allow display of the answers. The mouse or a Wacom pen (if available) will let you 'write in' answers.

2. I use Xodo on Android, but by default for security the Javascript is disabled. I suspect the answers can be displayed. It uses a pen/stylus if supported. Xodo probably works on Onyx.

3. I never heard of OCG. This just looks like a badly done PDF form, because it's easy to make them that typing works. (but not on ereader).

On Sage and Elipsa you can use a pen to write in the blank spaces. That works with any PDF. I've not tested if the answers display, but I suspect not. The Elipsa and Elipsa 2e can use the same version FW, so are the same.

On the Kindle Scribe I think you have send a PDF to Amazon and download it on the Scribe as KFX to be able to annotate it. Member @tomsem is expert on Kindle Scribe and will likely know even without testing if this works.

The reMarkable manages PDFs somewhat like the Kobo models. The two remarkable models can be using the same FW version. I've not got the reMarkable to hand so I don't know if it supports the javascript.

On the Elipsa, exactly as I thought, you can use the pen to write in. If you copy the PDF back to the PC, the written in answers are there. I think Kobo adds an extra image layer to the PDF. So the Sage and Elipsa 2 will be identical. The Form answers still can be turned on/off in Okular on the copied back PDF.

In general non-Android ereaders do not support anything other than viewing PDF and a TOC.

Someone expert with KOReader will know without testing if the answers can be displayed.

[Quoth]

Humorously if you put the demo pdf on a Kindle DXG (9.7″ 150 dpi) all the answers are shown.
They are not ever shown on a Kobo