Dynamic resizing of the display size

[olberger]

AFAIU, the display size is calculated initially, but it the browser's window is resized later, the X desktop won't adjust (well, noVNC has an option to stretch the rendering, etc.).

Would it be possible to use RandR to perform that, along the lines of https://stackoverflow.com/a/46295657 ?

[dennisvanderpool]

I have the same issue as well.
For me the resolution only is okay if i start the container with -e 1920x1080 or -e 2560x1440 so it's fixed.
With the autodetection i get strange resolutions and i want everything to run full screen in native resolution.
As i will be connecting from multiple devices with different screen resolutions any solution that allows me to change the resolution without creating container again with docker run is okay for me. I don't want to run the container everytime again as i need to reinstall and reconfigure it.

I know a container is meant to be stateless, but for my use case for the desktop that isn't that handy.

[dennisvanderpool]

I've got another one container desktop running, named Kasm web which has a working resize and is also based on noVNC and works with xrandr. Maybe we can peek there what they did?

https://hub.docker.com/u/kasmweb

You can also easily try it on their website:
https://www.kasmweb.com/

[fcwu]

I implemented resize when I worked at QNAP that is not based on xrandr. You may imagine user resize browser window by drag & drop and the screen resolution must change to fit browser window size. It's not a fixed resolution such as 1920x1080, 1280x720. It may be an arbitrary size like 1234x123. So writing a fixed resoulution in X configuration is not a good choice.

Alternatively, I run xvfb with a big size like 4096x3??? (4k) and a customized window manager that monitor all windows in it. When any window is out of visible range, window manager will move it to visible range.

[dennisvanderpool]

For me it would be great if we have an option, autosize or fixed. I'm okay with just the few fixed resolutions i use:
1920x1080
2560x1440
3440x1440
I even don't remind restarting the docker container, i just don't want to get it destroyed.

[fcwu]

@dennisvanderpool restart the docker container leads resizing xvfb. Here is my steps

1. Close browser's window
2. docker restart
3. Open browser again

In step3, it will call HTTP API api/reset?w=xxx&h=xxxx to resize

[tafulop]

@fcwu first of all, thanks for this great container, but I am experiencing some issues with it. I have tried to set the resolution with the RESOLUTION environment variable as it is stated in the How To, but it just simply does not work. I have tried the following things:

Start:
docker run -it --rm -p 6080:80 -p 5900:5900 -e RESOLUTION=1920x1080 ct2034/vnc-ros-kinetic-full

1st attempt:
Log in with Remmina -> resolution was 1024*768

2nd attempt (after recreating the container):
Login with Google Chrome -> resolution got reset to the usable space in the browser, which was 1920x949

Is this just me, or is it really not working properly?

[fcwu]

@tafulop open another issue.

[fcwu]

I have no plan to support this by RandR, because it's possible to change size by resizing browser window.

However, it's possible to change resolution without destroying container.

[fcwu]

I will create an endpoint /resize to restart xvfb to fitting current browser's window size. If someone would like to update screen size, append resize to original URL, for example, http://127.0.0.1:6080/resize. After updated, it will redirect to vnc page.

[pbek]

I will create an endpoint /resize to restart xvfb to fitting current browser's window size. If someone would like to update screen size, append resize to original URL, for example, http://127.0.0.1:6080/resize. After updated, it will redirect to vnc page.

@fcwu, thank you for this wonderful container, it fits all my Desktop needs (and I'm writing this comment from it 😁)!
Does the /resize endpoint already work? (I saw it in the source code). But I get a 404 error from nginx if I hit it. Is there another way to resize the resolution in the running container?

[fcwu]

it works

$ curl http://127.0.0.1:6080/resize
<html><head><script type = "text/javascript">var h=window.location.href;window.location.href=h.substring(0,h.length-6);</script></head></html>