HiDPI scaling on Linux

[benwaffle]

No description provided.

[metajack]

One thing you can do for now is use --device-pixel-ratio=2.0 (or 1.5 or 2.5 or whatever depending on what you want).

Do you happen to know what the normal method for doing this on Linux is? We do have support for this on Windows and Mac, although even there we could improve a bit, but mostly it is a matter of automating adjusting the device pixel ratio based on some system notification.

[benwaffle]

On GNOME desktops, you can read the gsettings key org.gnome.desktop.interface scaling-factor

[jbriggs-zvelo]

@benwaffle
GNOME with Wayland is fancier because it does scaling per monitor. I am not up on how that's done though.

[emberian]

On Wayland, you should listen to the wl_surface::enter/leave events (https://wayland.freedesktop.org/docs/html/apa.html#idp67102000), and take the scale from the wl_output::scale, resizing the internal buffer, using wl_surface::set_buffer_scale to match the output, and redrawing. When overlapping multiple outputs, I'm not sure what the best behaviour should be :)

Note that this is only for sizing the buffer: you'd probably still want to set the device pixel ratio using the wl_output::geometry to get some correspondence between a CSS px (which is an angular measurement) and a display px.

org.gnome.desktop.interface scaling-factor isn't ever useful for an application to read on Wayland, AFAIK.

[benwaffle]

somehow weston gets overlapping multi-dpi monitors perfect

[nox]

Is this still an issue?

[Manishearth]

Yeah, a page with a bit of text and some newlines renders like this under 2x:

The recommended fix -- setting --device-pixel-ratio=2.0 -- makes the text larger but it's still in a corner