QT_SCALE_FACTOR is set to 2 even if the Screen runs at 1920x1080

[skoehler]

Even though I have a 4K screen I run mate at 1920x1080. So when I login, the screen resolution changes to 1920x1080. Yet, mate does insist on setting QT_SCALE_FACTOR to 2 and QT_AUTO_SCREEN_SCALE_FACTOR to 0. I cant see any option to turn this off.

Can I disable setting those QT variables somehow? Or can I instruct MATE to enable QT_AUTO_SCREEN_SCALE_FACTOR and not set QT_SCALE_FACTOR?

Expected behaviour

QT_SCALE_FACTOR is set to 1

Actual behaviour

QT_SCALE_FACTOR is set to 2

Steps to reproduce the behaviour

Change the screen resolution from 3840x2160 to 1920x1080, logout, login, run some QT app

MATE general version

1.20.1

Package version

1.20.0-1

Linux Distribution

Arch Linux

Link to downstream report of your Distribution

n/a

[vkareh]

when I login, the screen resolution changes to 1920x1080

This part sounds strange. If you set the resolution and re-login, it shouldn't change: it should just be already set. The settings-daemon sets those env variables during the init phase, and of the resolution changes after that, yes, the QT_ vars would be stuck on the HiDPI values.

It sounds as though you have auto-detect on (org.mate.interface scaling-factor) and your screen is being detected as HiDPI even though you have a regular resolution. I've seen strange behavior like this for 4K monitors before...

@raveit65 you have a 4K monitor, right? Is this reproducible on your side? I did promise you a script to test and fix auto-detection and I didn't write it. Apologies, I had a surprise trip to visit a client, and now I'm on holiday this week with my family - I'll write it this week. I think it should help with this issue.

[skoehler]

Am 22.04.2018 um 00:31 schrieb Victor Kareh:

when I login, the screen resolution changes to 1920x1080 This part sounds strange. If you set the resolution and re-login, it shouldn't change: it should just be already set. The settings-daemon sets those env variables during the init phase, and of the resolution changes after that, yes, the QT_ vars would be stuck on the HiDPI values.

I'm using sddm as my display manager. It runs at 4K resolution, as far as I can tell. Then, when I login, mate changes the resolution to 1080p because 1080p is the resolution configured in my .config/monitor.xml

It sounds as though you have auto-detect on (|org.mate.interface scaling-factor|) and your screen is being detected as HiDPI even though you have a regular resolution. I've seen strange behavior like this for 4K monitors before...

I have a 4K screen, but I'm currently running it at 1080p. I assume that when sddm starts mate, the resolution is still set to 4K. Then the MATE desktop changes the resolution according to monitor.xml. The QT variables are probably set before the resolution is changed. It might also be that there is some sort of race because determining the screen density and changing the resolution happens in parallel.

[vkareh]

Got it, yeah this makes sense. I haven't used sddm, but I'll give it a try this week to try to fix this

[raveit65]

Can't say, i don't know how Qt scaling is working here, It seems that kaffeine scales fine but other apps like keepassx2 are 2 small, which are working with cinnamon session.
My current problem is more the cursor which starts to small in session and when i moved over applications it shows the wrong cursor image.
Which makes HIDPI unusable with marco WM.
I have to use metacity WM for working with my box.

[skoehler]

Am 22.04.2018 um 08:00 schrieb raveit65:

Can't say, i don't know how Qt scaling is working here, It seems that kaffeine scales fine but other apps like keepassx2 are 2 small, which are working with cinnamon session. My current problem is more the cursor which starts to small in session and when i moved over applications it shows the wrong cursor image. Which makes HIDPI unusable with marco WM. I have to use metacity VM for working with my box.

I'm having the opposite issue: Application are too big (not too small) cause I'm running a 4K screen at a 1080p resolution. For example KeePassXC and VirtualBox are twice the size they should be.

[raveit65]

Ahh, good hint, KeePassXC is working well with HIDPI :)
... using a Hidipi monitor means to switch to another applications..... ;)

I'm running a 4K screen at a 1080p resolution.

Maybe it's possible to override the session env ?

[raveit65]

[root@mother rave]# cat /etc/profile.d/qt-style.sh 
if [ "x$DESKTOP_SESSION" = "xmate" ] || [ "x$XDG_SESSION_DESKTOP" == "xmate" ]; then

	# QT apps to use GTK styling
    export QT_STYLE_OVERRIDE=gtk

    # Workaround clutter issue (LP: #1462445)
    export CLUTTER_BACKEND=x11

	# QT apps HIDPI scaling
    export QT_AUTO_SCREEN_SCALE_FACTOR=0
    export QT_SCALE_FACTOR=2.0
fi

Try creating such a file with updated values for your case.
Maybe this helps.

[vkareh]

@skoehler - I'm assuming this issue still persists? Could you run

gsettings set org.mate.interface window-scaling-factor 1

and restart your session? Let us know if the issue keeps happening afterwards. This setting forces the settings-daemon to a non-HiDPI scaling.

I'm looking at the code and I think I'm going to add an option to turn the QT scaling on/off. MATE currently makes the decision without giving the user an option to disable it.

[skoehler]

Setting window-scaling-factor to 1 worked for me.