[SOLVED] Configure two monitors

GPGAgent · 02-15-2021, 07:29 AM

I had this setup just how I wanted

https://www.linuxquestions.org/quest...re-4175690386/

But I accidentally dragged something somewhere (I think) and I've set up the displays to pan and mirror and I cannot see how to undo this.

Under Settings -> Display I've unticked the Mirror Settings but it makes no difference.

This is how it was:

Code:

jonke@charlie:~$ xrandr | grep -w connected
DP-0 connected primary 1920x1080+1024+0 (normal left inverted right x axis y axis) 598mm x 336mm
DP-1 connected 1024x768+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
jonke@charlie:~$

This is how it is now:

Code:

jonke@charlie:~$ xrandr | grep -w connected
DP-0 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 598mm x 336mm panning 2944x1080+0+0
DP-1 connected 1024x768+0+0 (normal left inverted right x axis y axis) 340mm x 270mm panning 2048x768+0+0 tracking 2944x1080+0+0 border 0/0/0/0
jonke@charlie:~$

I'm thinking I might need to just edit some config files, but I'm not entirely sure where and what to edit.

Any tips would be good, Mint 20 Xfce

GPGAgent · 02-15-2021, 07:52 AM

Well I've resolved the problem, but I don't understand why - look at the attached image

All I did was to un-tick the Primary Display and un-tick Mirror Displays

And I'm back to my original config

Code:

jonke@charlie:~$ xrandr | grep -w connected
DP-0 connected 1920x1080+1024+0 (normal left inverted right x axis y axis) 598mm x 336mm
DP-1 connected 1024x768+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
jonke@charlie:~$

Can someone explain what setting a Primary Display does?

obobskivich · 02-15-2021, 05:40 PM

'Primary Display' is considered as the 'main' display - where 0,0 originates - and where applications will want to start (especially fullscreen). Everything else is relative to it - e.g. 'left of' or +1920px of, or what-have-you.

Not sure what you did/undid but yes I've seen XFCE need settings to be 'set' and then 'set again' for it to update from the GUI control panel, not sure if this is a bug or user error.

GPGAgent · 02-15-2021, 06:13 PM

Quote:

Originally Posted by obobskivich

'Primary Display' is considered as the 'main' display - where 0,0 originates - and where applications will want to start (especially fullscreen). Everything else is relative to it - e.g. 'left of' or +1920px of, or what-have-you.

Not sure what you did/undid but yes I've seen XFCE need settings to be 'set' and then 'set again' for it to update from the GUI control panel, not sure if this is a bug or user error.

That's a nice clear explanation, thanks, now do you know how I could ajust these settings without resorting to the GUI's? I'm guessing I need to know mor about X windows/Xorg/xrandr?

Emerson · 02-15-2021, 06:24 PM

You can put your settings into Xorg conf files, sure. I use my ~/.xinitrc instead, have added three lines into it over time, these set up my displays the way I want them.

Code:

xrandr --output HDMI1 --mode 2560x1440
xrandr --output HDMI1 --primary --below DP1 
xrandr --output HDMI2 --same-as DP1

mrmazda · 02-15-2021, 08:29 PM

Any X startup script with xrandr will do the job. Here the "Screen Layout Editor" is arandr. In Debian I put the (one line) script in /etc/X11/Xsession.d/. The "primary" display by default hosts the panel (toolbar) at its bottom. For copy & paste purposes, the "script" used for the screenshot's configuration was:

Code:

xrandr --dpi 120 --output DP-1 --mode 2560x1440 --primary --output HDMI-2 --mode 2560x1080 --above DP-1

The -dpi option I use to make desktop text and icons both big enough to be comfortable, and visibly improved (higher effective pixel density).