Online whiteboard for PureOS?

Due to covid I am looking for an online whiteboard (of course with free license) for quick notes using a (wacom) pen. I teach Math and have organized a low resources way using mumble. The students receive a handwritten scanned pdf document with the notes to be presented in the next lecture and are required to have them printed out before the lecture starts. However, these notes are NOT fully written. There are missing parts. We all connect in a mumble channel and I present the material in audio with the students following the presentation on the printed notes completing the missing parts as they hear it. This method forces students to really attend the lecture, instead of watching you through BBB or jitsi or zoom where they end up …sleeping!

However, I have one more problem to solve. If a student asks a question for which I need to write something in order to explain I need a way to write a few quick notes with a (wacom) pen. But how to share this with the students? I do not want to enter a jitsi session for a quick note. Is there another way?

For example, I could have gimp open, write there and save a jpg file on a web page and ask them to reload the page. But this is kind of slow. Does anyone know of something faster, more interactive?

You could try https://cryptpad.fr/whiteboard/
They presented at Libre Graphics Meeting 2020. You can share a whiteboard via a link and it should have realtime viewing and editing. It’s also open source and they provide some storage with a free account.

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Oh my! this is sooooo coool. Thank you so much.

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That’s okay, tell me how it goes with your class and if it works for you. I’ve never used the writeboard.

OK. Classes start next week here. I let you know. Are you involved in this in some way?

No, I only poked around after hearing their talk and your question reminded me of the project. If you find it useful it’s always good to shot them a message about your appreciation. Keep the open-source community friendly. :smile:

I will contribute too (financially I mean) if I use it a lot.

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Security

CryptPad is private , not anonymous . Privacy protects your data, anonymity protects you. As such, it is possible for a collaborator on the pad to include some silly/ugly/nasty things in a CryptPad such as an image which reveals your IP address when your browser automatically loads it or a script which plays Rick Astleys’s greatest hits. It is possible for anyone who does not have the key to be able to change anything in the pad or add anything, even the server, however the clients will notice this because the content hashes in CryptPad will fail to validate.

The server does have a certain power, it can send you evil javascript which does the wrong thing (leaks the key or the data back to the server or to someone else). This is however an active attack which makes it detectable. The NSA really hates doing these because they might get caught and laughed at and humiliated in front of the whole world (again). If you’re making the NSA mad enough for them to use an active attack against you, Great Success Highfive, now take the battery out of your computer before it spawns Agent Smith.

Still there are other low-lives in the world so using CryptPad over HTTPS is probably a good idea.

:rofl: and yes the license is GNU AFFERO GENERAL PUBLIC LICENSE Version 3, 19 November 2007 < https://github.com/xwiki-labs/cryptpad/blob/main/LICENSE

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Yeah, it doesn’t cure cancer. It’s a tool that combined with other tools will keep you more private and/or more anonymous. Like Nextcloud, if you host it yourself you need to do hardening.
At least they are not lying, like when Google and Apple say they have good security. Their buildings are made of reinforced glass and not lead.

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In theory, any gtk3 application (like mypaint, maybe) can be launched using broadway (may have to compile gtk3+ yourself to get broadway support). This can then be viewed in a browser. You’d need a shim layer that rips the contents of the canvas out and shares it via webrtc. Mumble itself supports basic http, so you could even probably send it to the mumble server as a background image.

broadwayd also looks interesting. (For the moment I will stay with cryptpad because it looks stable) but I would like to learn this. I checked: https://developer.gnome.org/gtk3/stable/gtk-broadway.html
I run
GDK_BACKEND=broadway BROADWAY_DISPLAY=:5 gedit
and then open firefox at 127.0.0.1:8085 and I see the gedit window and can interact with it. But Now I open, say chrome/opera/seamonkey at the same address. And then on the firefox window I get the message “disconnected” and chrome takes over control of gedit.

So if this is not a bug, then this is a tool for remote execution. Not for showing your program to other people. Do I need to adjust anything so that more people can connect?

It’s a known limitation with broadway that it only allows a single connection at a time. That said, it paints the application into a canvas, so it is relatively simple to write a WebRTC script that synchronizes that canvas to multiple peers. Note that, while it easily becomes a GTK3 presentation system, it is not a collaboration system, as relaying input is considerably more complex.

OK. Not for me though.

It is not clear it works well even for one user. It is supposed to be used so you can launch remote apps and control them in browser. But for this to work you need to access the remote server with http. The server I have access to switches automatically to https and then the connection just fails. Is there a way out of this? At least it would be useful for remote execution.

Yes, you need to pass --cert and --key to broadwayd when it starts (Which means starting broadwayd and then starting your application, instead of auto-starting broadwayd when your application starts).

There have been a handful of projects to add authentication, or proxy multiple users, or similar, but none of them have gained any real traction (and are hard to actually find).