Seems like configuration by output description isn't working on Niri

[kepi]

Hi,

either I'm doing something wrong or outputs can't be configured by description on Niri. Which doesn't seem right as I see mention of niri outputs in regexp parts of configuration source code.

My outputs:

❯ niri msg outputs | grep Output
Output "ASUSTek COMPUTER INC ROG XG27AQ M1LMQS010079" (DP-1)
Output "Dell Inc. DELL P2723DE B1MP1L3" (DP-4)
Output "Dell Inc. DELL P2723DE G1MP1L3" (DP-5)

I thought this should work:

["Dell Inc. DELL P2723DE G1MP1L3"]
# ["re:G1MP1L3"]
# [DP-5]
duration = "1m"
path = "/home/kepi/Nextcloud/docs/wallpapers/1440x2560"

["ASUSTek COMPUTER INC ROG XG27AQ M1LMQS010079"]
# ["re:M1LMQS010079"]
[DP-4]
duration = "1m"
path = "/home/kepi/Nextcloud/docs/wallpapers/2560x1440"

["Dell Inc. DELL P2723DE B1MP1L3"]
# ["re:B1MP1L3"]
# [DP-1]
duration = "1m"
path = "/home/kepi/Nextcloud/docs/wallpapers/1440x2560"

["re:Surface"]
path = "/home/kepi/Nextcloud/docs/wallpapers/2880x1920"

But when I start wpaperd, I see that it is complaining about DP names, not description ones and wallpapers are not set.

❯ wpaperd
WARN [wpaperd::wpaperd]
   0: Configuration error on display DP-1
   1: Attribute path must be set

Suggestion: Add attribute path in the display section of the configuration:
path = "</path/to/image>"

Backtrace omitted. Run with RUST_BACKTRACE=1 environment variable to display it.
Run with RUST_BACKTRACE=full to include source snippets.
WARN [wpaperd::wpaperd]
   0: Configuration error on display DP-4
   1: Attribute path must be set

Suggestion: Add attribute path in the display section of the configuration:
path = "</path/to/image>"

Backtrace omitted. Run with RUST_BACKTRACE=1 environment variable to display it.
Run with RUST_BACKTRACE=full to include source snippets.
WARN [wpaperd::wpaperd]
   0: Configuration error on display DP-5
   1: Attribute path must be set

Suggestion: Add attribute path in the display section of the configuration:
path = "</path/to/image>"

As you can see commented out in config file, I tried regexps too as suggested, but with same result.

I can't depend on output ports as those changes on my setup.

Thanks for any tip.

[lairez]

Since niri is not based on wlroots, the output description is not what wpaperd expects. You can see what wpaperd sees using wlr-randr. I also created a PR #172 to make the error message more understandable.

[kepi]

I see, that make sense. But unfortunatelly if description from wlr-randr is wwl-root output, at least in my case, is useless:hat is used, than it is, at leats in my case, totally useless. This is my current output:

❯ guix shell wlr-randr -- wlr-randr --json | jq '.[] | .description'
"Dell Inc. - DELL P2723DE - DP-4"
"ASUSTek COMPUTER INC - ROG XG27AQ - DP-1"
"Dell Inc. - DELL P2723DE - DP-5"

There are two problems:

• missing serial numbers - first and last monitor are same (not counting port)
• port is in description - which is main problem of output based configuration :) if I turn off one of the monitor and restart, DP-5 would be DP-4 etc...

Btw looking at it now, for me it would be completely sufficient to have configuration based on serial numbers.

[lairez]

Then I guess the correct solution would be to patch smithay here (at this line https://github.com/Smithay/smithay/blob/62fab5a82648d8f6d04d89b61d41d68ed5e4abd1/src/output.rs#L267), to make the output description match that of wlroots.

[kepi]

Thanks for referencing that. TBH I'm now not sure if I should close this issue and try to advocate change in smithay or if wpaperd should support non wl-root based compositors and i.e. allow mathcing against serial?

I opened the issue mainly because I think it might be a problem for more people and it might be worth of fixing. But I'm all in for proper solutions instead of hacks.