Ordered output positioning

[ixxie]

challenge

The current positioning system for outputs is very precise in exchange for some rough edges:

• Users need to calculate positioning manually to configure monitor positions to their liking
• Configuration is not easily adaptable to variable output connections, e.g. if I use my HDMI output for various projectors and screens, I would need to configure them all manually

proposal

Add a secondary mechanism for positioning outputs called ordered positioning, which is configured with integer values:

output "eDP-1" {
     position order=0
}

output "HDMI-A-1" {
    position order=100
}

output "HDMI-A-2" {
    position order=-100
}

// connected to HDMI-A-2
output "Some Company CoolMonitor 1234" {
    // more specific than the connector, so overrides the previous
    position order=50
}

• When provided, orders would override output name in the automatic positioning algorithm.
• Orders would not be compatible with absolute positions, and Niri will throw a configuration error if the user tries to do this.
• When unconfigured monitors are added, their order is automatically chosen to be greater than the largest current value. If multiple monitors need to be assigned a position, they are sorted by their names as the absolute mode does.

This would already be valuable; what follows is extra 'nice to have' features that could be omitted or added later.

bonus

configuration

Global configuration options would allow tweaking things:

ordered-positioning {
   direction "right-to-left" // default is "left-to-right"
   align-to "center" // or "top" or "bottom", maybe even "stretch"
   auto-delta 100 // what value to add to automatically added output orders
}

action

When configuring outputs and the global auto-delta, you will have noticed I used 100 as the default different. This allows ad-hoc insertion of monitors between standard configured monitors. For example, in the above config example, the company monitor would go between the laptop monitor and the HDMI-A-1 output.

Likewise an action would allow setting the order:

niri msg action set-output-order "HDMI-A-1" 200

[YaLTeR]

Could there be a better property than order? It's not obvious that it does left-to-right positioning imo.

As for bonus: while I agree that niri positioning is somewhat limiting, I'm also not sure I'm prepared to add a lot of config content like this. Especially when, if I'm not mistaken, tools can use wlr-output-management to do this kind of positioning logic already?

[ixxie]

Alternative suggestions:

• position index=100
• auto-position 100
• position priority=100

Regarding the bonus: understandable about the config complexity; do you think the action is too much to ask for?

[ixxie]

Actually, what I didn't account for is the fact that Niri is designed with 2-dimensional orientation, since there are actions for up / down. One could also consider two-dimensional index:

• index x=100 y=0

y or x could be omitted and default to 0.