Public bug reported:
Dear community
Recently I upgraded my old netbook from Linux from Linux Mint 18 to Linux Mint
20
Distribution:
cat /etc/upstream-release/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=20.04
DISTRIB_CODENAME=focal
DISTRIB_DESCRIPTION="Ubuntu Focal Fossa"
Netbook is with small screen
1024x600
To get bigger virtual screen I use xrandr like:
xrandr --fb 1024x768 --output LVDS1 --panning 1024x768
To return to normal screen I use
xrandr --fb 1024x600
What is expected:
when the mouse moves outside the 1024x600 screen - new "clean" virtual area
appears.
What is in reality:
With fresh Ubuntu the first script results to wrong "background" image on the
extended area:
When I move mouse down below the original 600 pixels,
first 768-600=168 strings are shown like a background image.
Or
new virtual 601 string is the copy of the old 1
602 string is the copy of the old 2
...
768 string is the copy of the old 168
It looks like an index shift in the array:
The string which "disappears" from the top is moved to the bottom
This "background" image can be overwritten by the real application window.
For example, if I move the terminal window it appears on the top of this
"background"
But after moving mouse back inside the 1024x600 screen and back outside the
1024x600 screen,
the shifted copy of the top part of the screen appears at the bottom according
the
1->601
2->602 etc logic.
After playing a lot with xrandr parameters I had found a workaround:
One has to specify the first parameter in --fb bigger than the first parameter
in --panning
For example:
xrandr --fb 1025x768 --output LVDS1 --panning 1024x768
Here 1025>1024
I had checked this bug with two different laptops, so it is not related with
the hardware.
More information:
xrandr -v
xrandr program version 1.5.0
Server reports RandR version 1.6
The working configuration:
xrandr
Screen 0: minimum 8 x 8, current 1025 x 768, maximum 32767 x 32767
LVDS1 connected primary 1024x768+0+0 (normal left inverted right x axis y axis)
220mm x 130mm panning 1024x768+0+0
1024x600 60.19*+
1024x576 59.90 59.82
960x540 59.63 59.82
800x600 60.32 56.25
864x486 59.92 59.57
640x480 59.94
720x405 59.51 58.99
640x360 59.84 59.32
512x300 60.00
VGA1 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis
Wrongly working configuration:
xrandr
Screen 0: minimum 8 x 8, current 1024 x 768, maximum 32767 x 32767
LVDS1 connected primary 1024x768+0+0 (normal left inverted right x axis y axis)
220mm x 130mm panning 1024x768+0+0
1024x600 60.19*+
1024x576 59.90 59.82
960x540 59.63 59.82
800x600 60.32 56.25
864x486 59.92 59.57
640x480 59.94
720x405 59.51 58.99
640x360 59.84 59.32
512x300 60.00
VGA1 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)
Hope you can reproduce this bug.
Best regards, Dmitry
** Affects: xorg (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1923513
Title:
xrandr --panning problem
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