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#1 2021-10-09 00:38:16

Yegor-Beloglazov
Member
Registered: 2021-06-01
Posts: 6

blank space past desktop after using xrandr transformation

I have a television connected to my PC using S-Video. due to the nature of the TV, it cuts the outer edges of the screen off (no, there is no settings on the TV to fix this). To remedy this, i use

xrandr --output TV-0 --mode 1024x768 --transform 1.15,0,-72,0,1.15,-50,0,0,1 --right-of DVI-I-2

this scales the output down and moves it to be inside the edges of the screen, and it works except when i move my mouse past the right edge, it pans, it goes as far as ~3cm on the 40cm wide screen. I can make the screen not pan by appending --panning to the xrandr command:

xrandr --output TV-0 --mode 1024x768 --transform 1.15,0,-72,0,1.15,-50,0,0,1 --right-of DVI-I-2 --panning 1178x883+1280+0

I have to put in the scaled resolution instead of the actual resolution in the panning parameter otherwise xrandr throws an error. and the numbers are larger even though its smaller on my tv? i obtain the scaled resolution by running xrandr -q after applying the transform.
this fixes the panning issue, but the mouse still freely travels past the desktop and when i maximize a window it goes all the way to the end as well.

How do i fix the extra space past the desktop?

I am using an 8800GT video card with the nvidia-340xx driver from the AUR.

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#2 2021-10-09 06:47:56

seth
Member
Registered: 2012-09-03
Posts: 24,985

Re: blank space past desktop after using xrandr transformation

Does the viewport transformation in nvidia-settings yield better results?
What's the output of "xrandr -q" before and after the transormation?

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#3 2021-10-09 14:38:03

Yegor-Beloglazov
Member
Registered: 2021-06-01
Posts: 6

Re: blank space past desktop after using xrandr transformation

using nvidia-settings proves unreliable and i usually need to restart Xorg because it just seems to break. i write it off as bugginess due to the AUR driver only working with the modern kernel and Xorg versions due to patches by the maintainer

here is the output of xrandr -q in the 3 cenarios: https://pastebin.com/JuCe9mbX

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#4 2021-10-09 15:33:41

seth
Member
Registered: 2012-09-03
Posts: 24,985

Re: blank space past desktop after using xrandr transformation

TV-0 connected 1178x883+1280+0 (normal left inverted right x axis y axis) 0mm x 0mm panning 1250x883+1280+0 tracking 2530x1024+0+0 border

using nvidia-settings proves unreliable and i usually need to restart Xorg because it just seems to break.

Can you elaborate on this?
Does just running nvidia-settings "break" X11 or is it the viewport transformation in particular?
And how does it "break"?

Edit: https://askubuntu.com/a/868344

Last edited by seth (2021-10-09 15:37:31)

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#5 2021-10-09 16:55:32

Yegor-Beloglazov
Member
Registered: 2021-06-01
Posts: 6

Re: blank space past desktop after using xrandr transformation

when i try to apply any settings to the TV using nvidia-settings it seems to ignore any of my input and resets it to un-scaled 1024x768. and when i try to put it back where i had it using xrandr, it continuously errors even though it worked previously. xrandr works again after restarting X

The askubuntu thread linked unfortunately did not help.

I think I understand the issue, when i use xrandr to scale the display, it makes its reported resolution larger (1178x883) this makes nvidia make the entire Xscreen wider to acomodate this extra resolution even though nothing is being displayed there. using xrandr --fb to force it smaller makes it complain it is too small to fit all the displays. when i take a full screen screenshot, i can see the extra blank space on the end. this space is not there if no scaling is done

Im unsure how helpful it may be but here is 2 screenshots to show what i mean: https://imgur.com/a/f9oWhcz

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#6 2021-10-10 08:38:27

seth
Member
Registered: 2012-09-03
Posts: 24,985

Re: blank space past desktop after using xrandr transformation

That's "bad" because the xrandr transformations don't seem to work at all on 390xx…

What does work would be eg. to set
* the resolution to 1024x768
* ViewPortIn & Panning to 1000x748
* and ViewPortOut to 1000x748+12+10

But indeed this is very much depending on the actual driver sad

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