On X11, it’s possible to scale from 4:3 (or any other resolution) to 2560x1440 by
xrandr --output DP-2 --scale-from 1920x1440
However, Wayland does not have this feature yet.
There’s only custom resolution on Wayland, however nether it nor custom EDID is the solution, the monitor can’t handle the stretch, it has to be done by gpu.
Yes. This will stretch the screen horizontally. So round will be ellipses.
The most important is that the GPU does the stretching, so the monitor still receives native resolution.
A regular custom resolution, the stretch is done by the monitor.
Gamescope is the only Wayland compositor I know that allows changing the aspect ratio. Usually you can scale, rotate, mirror. But aspect ratio seems to be a rare use case that everybody seemingly ignored.
What is your scenario? Why do you want to stretch the image on that monitor?
Gamescope is certainly an option, but I think people are misusing it for just a aspect ratio stretching. It isn’t designed for mainly desktop PCs, and nested compositor introduces additional latency.
I did tried it for a while, it does not support native wayland well; and it cannot support KWin direct scanout unless set to sdl backend, which actually runs on X11, I cannot let it runs with --expose-wayland . Overall I rather runs on native resolution than bear the input latency it brings.
Thus I prefer a native Kwin stretching feature, but that option seems not to exist yet.
I don’t think we can do a direct scanout here, unless your monitor natively supports the resolution. Otherwise, the stretching must happen in the GPU somewhere, so your game must draw on an offscreen buffer.
Anyway, IIUC, you want apps to render to an arbitary “virtual resolution”, then kwin stretches it to a real resolution of your monitor (not keeping the aspect ratio). You might want to make a feature request on bugs.kde.org for this.