sotonpete
Posts: 6
Joined: Fri Jun 08, 2012 11:34 pm

Launch Chromium browser on second display?

Fri Jul 12, 2019 8:59 pm

Hi all,

I'm currently using a Pi to run a Kiosk dashboard for a charity call-centre, and having just upgraded to a Pi 4 I would like to attach a 7" touchscreen as well, to act as a control panel.

I've connected the 7" screen, and it's showing the same background picture as the main HDMI output, however I can't find a way of launching chromium-browser on that second screen (like I do on the first screen).

For the first screen I run...
DISPLAY=:0 /usr/bin/chromium-browser -force-device-scale-factor=1 --noerrdialogs --kiosk --incognito http://localhost:8080
Having done some Googling I've found that the command...
(cd /tmp/.X11-unix && for x in X*; do echo ":${x#X}"; done)
...which should list all displays known to X11, however it only returns one...
:0
If anybody has achieved this then I'd be most grateful to hear how!!

My build is Raspbian Buster

Many thanks,
Pete Bunting, UK.

User avatar
topguy
Posts: 5610
Joined: Tue Oct 09, 2012 11:46 am
Location: Trondheim, Norway

Re: Launch Chromium browser on second display?

Sat Jul 13, 2019 1:22 pm

Can you drag the chrome window (or any other window) with the mouse from one screen to the other ?

Each X-server ( :0 , :1 etc. ) can have sub displays.. you address those with adding another number.
See how these commands work.

Code: Select all

DISPLAY=:0.0  xeyes
DISPLAY=:0.1  xeyes
Edit:
xeyes are just a small app that shows some eyes that follow your mouse.. if for some reason its not installed you find it in the "x11-apps" package.

sotonpete
Posts: 6
Joined: Fri Jun 08, 2012 11:34 pm

Re: Launch Chromium browser on second display?

Sat Jul 13, 2019 1:50 pm

Thanks for the response.

I've just tried that and I get the eyes on the main screen using either...
DISPLAY=:0.0 xeyes
or
DISPLAY=:0 xeyes
...however if I try 0.1 I get...
DISPLAY=:0.1 xeyes
Error: Can't open display: :0.1
I think the issue is that the X windowing system is not aware of that second hardware screen?!?!

User avatar
topguy
Posts: 5610
Joined: Tue Oct 09, 2012 11:46 am
Location: Trondheim, Norway

Re: Launch Chromium browser on second display?

Sat Jul 13, 2019 2:18 pm

Can you drag the chrome window (or any other window) with the mouse from one screen to the other ?
Did you try this ? If its just an extended desktop I wound expect it to be "to the right of" or "below" the main deskop.

Since the second screen is showing the desktop-background it should be under control of the X-server. Isnt there a control/configuration panel for "display" somewhere ?

Also the output of the command "xrandr" ( ref: https://wiki.archlinux.org/index.php/Xrandr ) might tell us how it is configured.

I dont have a Raspbian Buster to test on yet, so I admit to taking a few stabs in the twilight here. Someone that knows exactly how it works might be back to work on monday.

sotonpete
Posts: 6
Joined: Fri Jun 08, 2012 11:34 pm

Re: Launch Chromium browser on second display?

Mon Jul 15, 2019 8:49 pm

Apologies for the delay in replying - I didn't have a mouse in the house! :)

So, now i've attached a mouse to the Pi I've found that it does indeed know about the second screen, and I can move the mouse cursor from one screen to the other!

Right clicking the desktop shows me that I have two Desktops - so I can configure separate backgrounds to each - even though they are in fact one constant flowing expanse.

I started to look at commands such as wmctrl to try and launch Chrome on one specific desktop, however on running...
DISPLAY=:0 wmctrl -d
...I got the response...
0 * DG: 2944x1080 VP: 0,0 WA: 0,0 2944x1080 desktop 1
...showing that as far as X was concerned, it was one screen.

I've now found that I can launch Chrome on to that second window using...
DISPLAY=:0 /usr/bin/chromium-browser \
--noerrdialogs \
--kiosk \
--incognito \
--window-position=1920,0 \
http://localhost:8080/secondpage
...and all is as I'd hoped!!

Many thanks for your input topguy! :)

Regards,
Pete.

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