tizian
Posts: 1
Joined: Sat Oct 12, 2019 5:36 pm

Pi4 dual screen: window span over both screens by cmdline?

Sat Oct 12, 2019 8:15 pm

Hi,
anyone an idea? thanks in advance!

My question:
I try to open a window with cmdline which is fullscreen over both screens. In my case a chromium browser window.

My setting:
I use a Raspi 4 B and have connected two identical 19" Displays on the HDMI ports. The newest version of Raspian is installed. Monitor detection works fine direct from startup.

The following line is opening a fullscreen window on one display. unfortunately I found no option to have the window over both screens.

Code: Select all

chromium-browser --incognito --kiosk http://google.com

dakky_tz
Posts: 2
Joined: Mon Oct 21, 2019 9:00 pm

Re: Pi4 dual screen: window span over both screens by cmdline?

Mon Oct 21, 2019 9:07 pm

Hi,

I am interested if there is any possibility to have a window maximized over two displays with Raspberry Pi4 and Raspbian OS. I am trying to get Citrix to detect and use both displays during a session and since I cannot maximize over both screens the session wont work in dual display mode.

Anyone have any idea how to resolve this?

Thanks

User avatar
HermannSW
Posts: 2767
Joined: Fri Jul 22, 2016 9:09 pm
Location: Eberbach, Germany
Contact: Website Twitter YouTube

Re: Pi4 dual screen: window span over both screens by cmdline?

Tue Jan 14, 2020 8:19 pm

I assume you tried from console and not X11.

There is only one framebuffer (/dev/fb0) when both HDMI displays are connected.
And when booting into console mode I see the same console output on both.
So what you want is not possible in console mode, you need X11.

I switched to boot into X11, and here a window can definitely span over two displays.
The right terminal shows only minimally on right side of 1360x768 HDMI-0.
And only minimally on left side of 1024x768 HDMI-1.
Most of the terminal is "between" both (top left coordinate of HDMI-0 is (0,0), of HDMI-1 is (1920,0)].

Code: Select all

$ cat ~/.xsessionrc
xrandr --output HDMI-1 --mode 1360x768
xrandr --output HDMI-2 --mode 1024x768
$
Taking screenshot with "scrot" captures 1920+1024=2944 × 768 image:
Image


P.S:
Here the two HDMI displays span a 3472x2200 X11 root window.
xlock started with "-geometry 3455x2150+5+5" nearly fills all of that, see screenshot.
Details here:
https://www.raspberrypi.org/forums/view ... 8&t=261980
Image
https://stamm-wilbrandt.de/en/Raspberry_camera.html
https://stamm-wilbrandt.de/en#raspcatbot
https://github.com/Hermann-SW/raspiraw
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://stamm-wilbrandt.de/github_repo_i420toh264

aBUGSworstnightmare
Posts: 2044
Joined: Tue Jun 30, 2015 1:35 pm

Re: Pi4 dual screen: window span over both screens by cmdline?

Wed Jan 15, 2020 5:11 am

HermannSW wrote:
Tue Jan 14, 2020 8:19 pm
I assume you tried from console and not X11.

There is only one framebuffer (/dev/fb0) when both HDMI displays are connected.
And when booting into console mode I see the same console output on both.
So what you want is not possible in console mode, you need X11.

I switched to boot into X11, and here a window can definitely span over two displays.
The right terminal shows only minimally on right side of 1360x768 HDMI-0.
And only minimally on left side of 1024x768 HDMI-1.
Most of the terminal is "between" both (top left coordinate of HDMI-0 is (0,0), of HDMI-1 is (1920,0)].

Code: Select all

$ cat ~/.xsessionrc
xrandr --output HDMI-1 --mode 1360x768
xrandr --output HDMI-2 --mode 1024x768
$
Taking screenshot with "scrot" captures 1920+1024=2944 × 768 image:
Image


P.S:
Here the two HDMI displays span a 3472x2200 X11 root window.
xlock started with "-geometry 3455x2150+5+5" nearly fills all of that, see screenshot.
Details here:
https://www.raspberrypi.org/forums/view ... 8&t=261980
Image
Hermann, if your desktop looks like this then there is something wrong! Are you using fkms driver or legacy driver (configured for dual screen)

User avatar
HermannSW
Posts: 2767
Joined: Fri Jul 22, 2016 9:09 pm
Location: Eberbach, Germany
Contact: Website Twitter YouTube

Re: Pi4 dual screen: window span over both screens by cmdline?

Wed Jan 15, 2020 2:24 pm

aBUGSworstnightmare wrote:
Wed Jan 15, 2020 5:11 am
Hermann, if your desktop looks like this then there is something wrong! Are you using fkms driver or legacy driver (configured for dual screen)
What is wrong?
The background image is tiled over the big X11 root window.
All works as expected, details in the other thread.
This is setting in /boot/config.txt:

Code: Select all

...
[pi4]
# Enable DRM VC4 V3D driver on top of the dispmanx display stack
dtoverlay=vc4-fkms-v3d
...
https://stamm-wilbrandt.de/en/Raspberry_camera.html
https://stamm-wilbrandt.de/en#raspcatbot
https://github.com/Hermann-SW/raspiraw
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://stamm-wilbrandt.de/github_repo_i420toh264

aBUGSworstnightmare
Posts: 2044
Joined: Tue Jun 30, 2015 1:35 pm

Re: Pi4 dual screen: window span over both screens by cmdline?

Wed Jan 15, 2020 7:12 pm

HermannSW wrote:
Wed Jan 15, 2020 2:24 pm
What is wrong?
The background image is tiled over the big X11 root window.
...
it shouldn't be tiled like this. And why is it 1920+1024 if you set mode to 1360+1024?

User avatar
HermannSW
Posts: 2767
Joined: Fri Jul 22, 2016 9:09 pm
Location: Eberbach, Germany
Contact: Website Twitter YouTube

Re: Pi4 dual screen: window span over both screens by cmdline?

Wed Jan 15, 2020 7:28 pm

aBUGSworstnightmare wrote:
Wed Jan 15, 2020 7:12 pm
HermannSW wrote:
Wed Jan 15, 2020 2:24 pm
What is wrong?
The background image is tiled over the big X11 root window.
...
it shouldn't be tiled like this. And why is it 1920+1024 if you set mode to 1360+1024?
Because the background image is 1920x... and Raspian decided to place HDMI-2 right to background image initially.
Position of HDMI-[12] can be changed easily with "Preferences -> Screen Configuration" tool.
I increased the X11 root window size using that tool (up to 5000x5000).
You can see HDMI-1 top left and HDMI-2 bottom right, both in tool and root window snapshot.

https://www.raspberrypi.org/forums/view ... 0#p1595356
Image
https://stamm-wilbrandt.de/en/Raspberry_camera.html
https://stamm-wilbrandt.de/en#raspcatbot
https://github.com/Hermann-SW/raspiraw
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://stamm-wilbrandt.de/github_repo_i420toh264

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