Flickering when using accessibility zoom (magnifier)

drslmr · 2025-04-10 06:46:56

Since a longer time the screen shows flickering and distortion when using the accessibility-zoom. Sorry I don't remember when it started but it used to be fine some time ago. I use two monitors.

Interestingly, when I turn on "Crosshair Lines" in the Settings, the flickering disappears and everything looks fine.

I'm using gnome.

Last edited by drslmr (2025-04-10 07:40:50)

seth · 2025-04-10 14:14:28

Some basic information about the system (hardware, drivers, display server, amount of outputs) would be good and if you can capture the "flickering and distortion" for illustration that might help to gage the problem as well.

drslmr · 2025-04-11 13:07:30

Thanks for the reply.

It looks like this is not a common problem and I have a workaround so I guess it is not worth spending a lot of time into this issue?

Anyway, here is some information:

It is a DELL with HDMI and Display output used with two monitors.

local/wayland 1.23.1-1
    A computer display server protocol
local/xorg-server 21.1.16-1 (xorg)
    Xorg X server
local/gdm 48.0-1 (gnome)
    Display manager and login screen

Here is some more information:

$ lspci 
00:00.0 Host bridge: Intel Corporation 12th Gen Core Processor Host Bridge (rev 05)
00:02.0 VGA compatible controller: Intel Corporation Alder Lake-S GT1 [UHD Graphics 770] (rev 0c)
00:04.0 Signal processing controller: Intel Corporation Alder Lake Innovation Platform Framework Processor Participant (rev 05)
00:08.0 System peripheral: Intel Corporation 12th Gen Core Processor Gaussian & Neural Accelerator (rev 05)
00:14.0 USB controller: Intel Corporation Alder Lake-S PCH USB 3.2 Gen 2x2 XHCI Controller (rev 11)
00:14.2 RAM memory: Intel Corporation Alder Lake-S PCH Shared SRAM (rev 11)
00:16.0 Communication controller: Intel Corporation Alder Lake-S PCH HECI Controller #1 (rev 11)
00:17.0 SATA controller: Intel Corporation Alder Lake-S PCH SATA Controller [AHCI Mode] (rev 11)
00:1a.0 PCI bridge: Intel Corporation Alder Lake-S PCH PCI Express Root Port #25 (rev 11)
00:1c.0 PCI bridge: Intel Corporation Alder Lake-S PCH PCI Express Root Port #3 (rev 11)
00:1f.0 ISA bridge: Intel Corporation Device 7a86 (rev 11)
00:1f.3 Audio device: Intel Corporation Alder Lake-S HD Audio Controller (rev 11)
00:1f.4 SMBus: Intel Corporation Alder Lake-S PCH SMBus Controller (rev 11)
00:1f.5 Serial bus controller: Intel Corporation Alder Lake-S PCH SPI Controller (rev 11)
01:00.0 Non-Volatile memory controller: Solid State Storage Technology Corporation CL4-8D512 NVMe SSD M.2 (DRAM-less) (rev 03)
02:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8211/8411 PCI Express Gigabit Ethernet Controller (rev 1b)

seth · 2025-04-11 14:25:41

It looks like this is not a common problem and I have a workaround so I guess it is not worth spending a lot of time into this issue?

That's gonna be up to you.
If you're curious:

loginctl session-status

Does it happen when removing the second output?
Since gnome will most likely default to wayland, is gnome on xorg affected as well?
Do you use https://wiki.archlinux.org/title/HiDPI# … al_scaling or similar?

I could imagine that the crosshair requires full framebuffer repaints where otherwise only the magnified area has to be updated and that somehow™ exposes some underlying issue.

drslmr · 2025-04-11 16:42:46

Thanks again, I will check next week.
I took a picture but was unable to post it here.

drslmr · 2025-04-14 12:07:24

Some more details:

  Since: Mon 2025-04-14 08:20:05 CEST; 2h 15min ago
  State: active
 Leader: 1316 (gdm-session-wor)
   Seat: seat0; vc2
    TTY: tty2
 Remote: no
Service: gdm-password
   Type: x11
  Class: user
   Idle: no
   Unit: session-3.scope
         ├─1316 "gdm-session-worker [pam/gdm-password]"
         ├─1432 /usr/lib/gdm-x-session --run-script /usr/bin/gnome-session
         ├─1436 /usr/lib/Xorg vt2 -displayfd 3 -auth /run/user/17700/gdm/Xauthority -nolisten tcp -background none -noreset -keeptty -novtswitch -verbose 3
         └─1449 /usr/lib/gnome-session-binary

Looks like I'm using Xorg not Wayland.

org.gnome.desktop.interface scaling-factor uint32 0
org.gnome.settings-daemon.plugins.xsettings overrides {'Gdk/WindowScalingFactor': <1>}

With only one monitor it is fine.

And, yes it looks like the properly displayed part is just about the area of one monitor. Around that properly displayed region the distortion or flickering occurs.

When using wayland the problem is the same:

 Since: Mon 2025-04-14 12:34:32 CEST; 21s ago
  State: active
 Leader: 1284 (gdm-session-wor)
   Seat: seat0; vc2
    TTY: tty2
 Remote: no
Service: gdm-password
   Type: wayland
  Class: user
   Idle: no
   Unit: session-3.scope
         ├─1284 "gdm-session-worker [pam/gdm-password]"
         ├─1408 /usr/lib/gdm-wayland-session /usr/bin/gnome-session
         └─1414 /usr/lib/gnome-session-binary

seth · 2025-04-14 14:38:52

using wayland the problem is the same

With only one monitor it is fine.

the properly displayed part is just about the area of one monitor. Around that properly displayed region the distortion or flickering occurs.

https://gitlab.gnome.org/GNOME/mutter/-/issues/3362
Might also relate to https://gitlab.gnome.org/GNOME/mutter/-/issues/3906 and/or https://gitlab.gnome.org/GNOME/mutter/-/issues/2743

drslmr · 2025-04-16 06:04:09

The first one looks quite similar to my issue.
The seemingly fixing effect of using cross hairs is not mentioned. This for me works even if the cross hairs are set to the smallest size possible,

Arch Linux

#1 2025-04-10 06:46:56

Flickering when using accessibility zoom (magnifier)

#2 2025-04-10 14:14:28

Re: Flickering when using accessibility zoom (magnifier)

#3 2025-04-11 13:07:30

Re: Flickering when using accessibility zoom (magnifier)

#4 2025-04-11 14:25:41

Re: Flickering when using accessibility zoom (magnifier)

#5 2025-04-11 16:42:46

Re: Flickering when using accessibility zoom (magnifier)

#6 2025-04-14 12:07:24

Re: Flickering when using accessibility zoom (magnifier)

#7 2025-04-14 14:38:52

Re: Flickering when using accessibility zoom (magnifier)

#8 2025-04-16 06:04:09

Re: Flickering when using accessibility zoom (magnifier)

Board footer