Per-application display scaling on Linux using the Sway WM instances

A demonstration of a bit hacky, but simple method for getting per-application display scaling on Linux desktop.

Purpose of this is to better display the user interfaces of older applications, that do not normally scale up to the modern screen resolutions and therefore appear tiny.

It is done by containing the target application windows in a Sway window manager instance virtual display window, with a custom output scale applied.

Running Sway as the host graphical environment is not required. Sway can be launched in a window under X11 and Wayland. This is why I think this solution should work OK in most Linux GUI environments.

This repository is not a library, so just copy and modify these files to suit your needs.

Usage

To launch application ddd at the display output scale multiplied by 1.25:

swayscale "1.25" "ddd"

Setup

1. Install sway, xorg-xwayland.

2. Copy the repository files under the respective locations in your $HOME directory.

   git clone "https://github.com/andis-sprinkis/swayscale"
   cd "./swayscale"
   mkdir -p "${XDG_CONFIG_HOME:-$HOME/.config}/sway" "$HOME/.local/bin"
   cp ".local/bin/swayscale" "$HOME/.local/bin/swayscale"
   cp ".config/sway/custom_scale" "${XDG_CONFIG_HOME:-$HOME/.config}/sway/custom_scale"
   chmod +x "$HOME/.local/bin/swayscale"

3. Ensure that the directory path $HOME/.local/bin/ is in the $PATH variable.

   Add the line to .profile / .bash_profile / .zshenv and re-login:

   export PATH="$HOME/.local/bin:$PATH"

You may have to update font sans-serif medium in the exec line at the bottom of .config/sway/custom_scale to a font identifier that actually exists on the system (run fc-list).

Desktop files

To launch the upscaled application from the application launcher of a Linux desktop environment, a Desktop file can be created in ${XDG_DATA_HOME:-$HOME/.local/share}/applications/ directory.

See the example ddd_upscaled.desktop file.

Related specifications: "Desktop Entry Specification", "Association between MIME types and applications".