"Fixing" HiDPI issues

[elParaguayo]

I'm working on a solution for users with high resolution screens. My current plan is to allow a dpi= argument to Screen objects in our configs so this can be configured on a per screen basis.

I then plan to use that value to scale the following aspects in qtile (tick means I've got it working):

• bar height
• widget text
• widget icons
• bar borders
• window borders

Questions for people here:

• Is this the right approach? If not, what do you recommend?
• What have I missed from the above list?

[cr1ogen]

I change the dpi I am changing the screen scaling through autostart.sh with commands that use wlr-randr, since I use wayland. Maybe this can only be implemented by setting the dependency wlr-randr for wayland and xrandr for X11 and putting the commands in the config.py file
Maybe it's not a good idea, or yes, since I'm not a programmer. But you could see it. Thank you

[elParaguayo]

Doesn't screen scaling cause blurring? The solution I'm proposing here ensures that the items I've listed would be rendered at that larger size without the need for scaling but that only covers qtile items. App windows etc wouldn't be impacted.

[cr1ogen]

I not see it blurring when i scale the resolution

[cr1ogen]

The scaling screen solution, I copy from the wiki of sway

[cr1ogen]

[tych0]

We talked about this a bit here: #4693 ; I think you'll need a way to stabilize which screen is which, given that x11 won't order them in the same way across boots. IMO the best way is to use the serial number, because that's what's printed on the back of the monitor. I have code to grab the serial number using x11+pyedid, but the edid specification is so small (and we probably only care about the serial number + maybe recommended resolutions) that maybe it's worth just coding our own small implementation.

I think you are on the right track in terms of needing scaling calculations for everything. Two points I would offer: 1. you can compute the DPI based on xrandr outputs (I have code for that as well in the above script), so you don't need DPI (or anything) as a user input unless people want to run things at non-native resolutions, 2. it is useful to be able to run at non native resolutions so that you can drag your mouse across screens smoothly; it is blurry as you say, though. I run one 4k monitor and two non-4ks at 4k for exactly this reason. It doesn't look awful, but I agree it doesn't look great :)

Still, having math to do DPI scaling natively in qtile would be great. I'm happy to look at/test any progress you have.

[jwijenbergh]

Yes, see https://gitlab.freedesktop.org/wlroots/wlroots/-/blob/0.16/include/wlr/types/wlr_output.h?ref_type=heads#L132

[tych0]

oh, nice. i can probably even write an untested version of the wayland code with that link. i'll do that soon, thanks!

[elParaguayo]

OK. Help me out here. If I adjust the scale value in wephyr and reconfigure_screens, everything's scaled, windows, bar, borders etc and it looks blurry. I had assumed that's what we're trying to avoid i.e. we can keep scale at 1 but scale up bar, borders etc before rendering. Am I missing something?

[cr1ogen]

Shouldn't they deploy wlroots to 0.17 before making these changes?

[elParaguayo]

This one's going to take a while anyway and we need something for x11, not just wayland.

[tych0]

OK. Help me out here. If I adjust the scale value in wephyr and reconfigure_screens, everything's scaled, windows, bar, borders etc and it looks blurry. I had assumed that's what we're trying to avoid i.e. we can keep scale at 1 but scale up bar, borders etc before rendering. Am I missing something?

I think you're right that we want the default to be scale=1, but I am interested in adjusting the scale down instead of up: I want to render 3x 4k monitors in software, but scale it down by ~0.6 to render on my physical displays, which are really 1920x1200 or whatever. (My practical reason for this is so that my mouse lines up when I drag it across monitors. Maybe there's actually a better way to implement that, though? In which case, perhaps we'd always want scale=1.) I agree that once we have this capability, it doesn't really make sense for anyone to set scale > 1, though. They will definitely prefer rendering at the native resolution.

[tych0]

Yeah... https://superuser.com/questions/1119204/move-mouse-proportionally-between-different-resolution-and-dpi-displays looks like it has a few different solutions. Maybe I'll play around with those. I agree it would be much simpler/better to render everything at its preferred native resolution.