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piomiq

Member

From: Warsaw, Poland

Registered: 2017-08-04

Posts: 25

Website

Is there a way to detect whether an external screen is in on/off mode?

Hi

I'm trying to detect if my external monitor is turned on/off. I need this because usually my external screen is tuned off I turn on it occasionally. Just because this is projector. The issue is that KDE/Plasma sees it even screen is turned off, but connected (here via HDMI). In result I can move mouse on invisible screen, right corner functionality doesn't work, I can move window on this screen and sometimes on this invisible screen I got running windows. To work around this I just set in KDE/Plasma showing new window on cursor position.

I found that xrandr only returns status if any screen if connected or not. I would like to know also if is turned on/off just to be able switch off/on it by xrandr.
In this moment I turn off secondary screen for sddm (by script /usr/share/sddm/scripts/Xsetup) to get one login screen otherwise I have two login screens on one (my screens  have different resolution, so it looked really ugly).

Thanks in advance.

ewaller

Administrator

From: Pasadena, CA

Registered: 2009-07-13

Posts: 19,772

Re: Is there a way to detect whether an external screen is in on/off mode?

Take a look at https://bbs.archlinux.org/viewtopic.php?id=257700
This is marginally the same issue.  I'll leave this open for now in case it is not.

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piomiq

Member

From: Warsaw, Poland

Registered: 2017-08-04

Posts: 25

Website

Re: Is there a way to detect whether an external screen is in on/off mode?

Thank you for url with similar topic. Unfortunately issue wasn't solved. Therefore still I don't know how to detect if external monitor is on/off. I'm digging in Internet but cannot find any solution.

I tried following things:

• xrandr reports always connected no matter if display is on/off (tested on monitor and projector)

• xset -q shows always "Monitor is On" and not matter if display is on/off (tested on both devices)

• xev shows nothing, called like this: xev -root -event randr

• x-on-resize shows nothing, called like this: x-on-resize -a or x-on-resize -s :0

• sudo ddccontrol -p the displays detected (need to be i2c kernel modules loaded), but no information if they are turn on/off. At end says that "Missing monitors supported DDC/CI".

• sudo ddcutil the displays detected (need to be i2c kernel modules loaded), but no information if they are turn on/off

• sudo udevadm monitor --property reports something if I turn off my primary monitory, but when I turn on and off projector nothing happens.

Last edited by piomiq (2020-08-07 22:59:09)