Apps don't scale well on large screens

[ctnlaring]

I tried running all the flatpak apps on a 65" screen and nothing scales properly

[plfiorini]

Ah that's the Qt autoscaling it thinks device pixel ratio is greater than 1 (probably 2 or even 3).
qtdiag should tell you more but it's not part of the runtime, it's in the SDK only so you cannot run that from flatpak.

Can you try running xrandr and report the output instead?

[ctnlaring]

$ xrandr
Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 8192 x 8192
VGA-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-2 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 160mm x 90mm
1920x1080 60.00*+ 59.94 30.00 24.00 29.97 23.98
1920x1080i 60.00 59.94
1680x1050 59.88
1600x900 60.00
1280x1024 75.02 60.02
1440x900 59.90
1366x768 59.79
1280x800 59.91
1152x864 75.00
1280x720 60.00 59.94
1024x768 75.03 70.07 60.00
832x624 74.55
800x600 72.19 75.00 60.32
720x480 60.00 59.94
720x480i 60.00 59.94
640x480 75.00 72.81 66.67 60.00 59.94
720x400 70.08
DP-2 disconnected (normal left inverted right x axis y axis)

[plfiorini]

160 mm x 90 mm for a 65" screen doesn't seem right is it a Samsung isn't it? :)

[ctnlaring]

Ah yes. I'd forgotten. The system has always thought it was 7"

[plfiorini]

Samsung is known to confuse mm with cm so it reports the wrong physical size to Qt.
I'm considering turning high-dpi support off on X11.

[plfiorini]

On Wayland, with our compositor, I can make adjustments and correct bad monitors for example always use a scale factor of 1 if the resolution is <= 1920x1080 but on X11 I have to submit a patch to Qt that is unlikely to be accepted because with this kind of corrections it gets complicated.

[plfiorini]

Btw even if it was meant to be 160 cm x 90 cm it's a bit weird for a 65" screen, it should be about 140 cm x 80 cm

[ctnlaring]

It might not actually be 65" but somewhere around there

[timsueberkrueb]

I actually have the same problem on my laptop. Is there a workaround @plfiorini?

[timsueberkrueb]

Nevermind, running apps/the shell with QT_AUTO_SCREEN_SCALE_FACTOR=0 works around the problem (see http://doc.qt.io/qt-5/highdpi.html).

[plfiorini]

This is a hardware problem (wrong physical size being reported) but Qt needs to be patched make it clever and report devicePixelRatio = 1.0 if the resolution is lower or equal to 1920x1080 so this is an upstream issue.

[ItsShadowCone]

This should definitely be configurable. The only thing I really hate is that I got a relatively small display (14") but full HD and scaling wastes a terrible amount of space. I dont care about things being small as long as I have lots of space and I definitely want to have scaling configurable.