Set-Scale-for-Multi-Monitor-Setup

A Python utility to programmatically set individual display scaling factors for multi-monitor setups in GNOME (via D-Bus).

This script is particularly useful for users who need to toggle scaling frequently or want to automate their display configuration without using the GNOME Settings GUI.

Features

• Per-monitor scaling: Assign specific scaling factors (e.g., 1.0, 1.25, 2.0) to different displays.
• D-Bus Integration: Directly communicates with org.gnome.Mutter.DisplayConfig.
• Safe Execution: Uses the system's Python 3 to ensure dbus library availability.

Prerequisites

• GNOME Desktop Environment (Mutter window manager).
• Python 3 with python3-dbus installed (usually pre-installed on Ubuntu/Fedora).

Configuration

Before running the script, you need to identify your monitor connector names and define your desired scaling in the SCALE_MAP dictionary within set_scale_multi.py.

1. Identify your Monitor Names

Run the following command in your terminal:

xrandr --query | grep " connected"

Common names are eDP-1 (internal laptop display), HDMI-1, or DP-1.

2. Edit the script

Update the SCALE_MAP in the script:

SCALE_MAP = {
    "eDP-1": 1.0,   # Example: Internal Display
    "HDMI-1-0": 2.0 # Example: External 4K Monitor
}

Usage

Make the script executable and run it:

chmod +x set_scale_multi.py
./set_scale_multi.py

Troubleshooting

"InvalidArgs: Logical monitor scales must be identical"

If you encounter this error, your system (likely under X11) does not support different scaling factors per monitor nativelly.

Solution for Wayland users: Enable the experimental fractional scaling feature:

gsettings set org.gnome.mutter experimental-features "['scale-monitor-framebuffer']"

Note: A logout/login or restart might be required.

Credits

Based on discussions and snippets from AskUbuntu and strycore's gist.