dos.py

""" DisplayOriginSwap (dos)

Swaps the position of two displays using the displayplacer command line utility.
Provides a workaround to the issue where Macs will randomly reverse the screen arrangement of identical external displays.
"""

import subprocess
import sys

def get_display_list():

    # Create a list to store extracted displayplacer data as dictionaries
    display_list = []

    # Run the "displayplacer list" command and split it into lines
    output = subprocess.run(["displayplacer", "list"], capture_output=True).stdout.decode()
    lines = output.strip().split("\n")

    # Temporary dictionary to store data for each display
    current_display_data = {}

    print("Detected screens:")
    # Find lines that contain either the id, resolution or origin, and split at the colon.
    # Append the data to the dictionaries and add them to the display_list list.

    for line in lines:
        if "Persistent screen id:" in line:
            current_display_data["screen_id"] = line.split(":")[1].strip()
        
        if "Type:" in line:
            current_display_data["type"] = line.split(":")[1].strip()

        if "Resolution:" in line:
            current_display_data["resolution"] = line.split(":")[1].strip()

        if "Origin:" in line:
            current_display_data["origin"] = line.split(":")[1].strip()
            display_list.append(current_display_data)
            screen_index = display_list.index(current_display_data)
            print(f"screen {screen_index}: {current_display_data}")
            current_display_data = {}
    return(display_list)

def validate_inputs(displays_to_swap, display_list):
    # Check if the display indexes in displays_to_swap are within the range of available displays.
    if any(d >= len(display_list) for d in displays_to_swap):
        print("Error: One or more display indexes in displays_to_swap do not reference a detected screen.")
        sys.exit(1)

def print_display_info(displays_to_swap, display_list):
    print("\nSwapping display origin of screens:")
    for i, d in enumerate(displays_to_swap):
        print(f"screen {d}: type:{display_list[d]['type']} resolution:{display_list[d]['resolution']} \t current origin:{display_list[d]['origin']} \t new origin:{display_list[displays_to_swap[1 - i]]['origin']}")

def swap_displays(displays_to_swap, display_list):
    displayplacer_arguments = [
        f"id:{display_list[d]['screen_id']} resolution:{display_list[d]['resolution']} origin:{display_list[displays_to_swap[1 - i]]['origin']}"
        for i, d in enumerate(displays_to_swap)
    ]

    print("\nExecuting:")
    print(f"displayplacer \"{displayplacer_arguments[0]}\" \"{displayplacer_arguments[1]}\"")

    output = subprocess.run(["displayplacer", displayplacer_arguments[0], displayplacer_arguments[1]], check=True, capture_output=True).stdout.decode()

    print(output)

def main():
    displays_to_swap = (1, 2)
    display_list = get_display_list()

    validate_inputs(displays_to_swap, display_list)
    print_display_info(displays_to_swap, display_list)
    swap_displays(displays_to_swap, display_list)

if __name__ == "__main__":
    main()