Update the GNOME desktop wallpaper with a random image from Unsplash.

update_wallpaper.py

#! /usr/bin/env python3

import argparse
import logging
import subprocess
from pathlib import Path

import dbus
import requests

Resolution = tuple[int, int]


def get_max_screen_res() -> Resolution:
    bus = dbus.SessionBus()
    display_config = bus.get_object(
        "org.gnome.Mutter.DisplayConfig", "/org/gnome/Mutter/DisplayConfig"
    )
    _, monitors, _, _ = display_config.GetCurrentState(
        dbus_interface="org.gnome.Mutter.DisplayConfig"
    )

    max_width, max_height = 0, 0

    for monitor in monitors:
        modes = monitor[1]
        for mode in modes:
            properties = mode[6]
            is_current = "is-current" in properties and properties["is-current"]
            if is_current:
                width = int(mode[1])
                height = int(mode[2])

                max_width = max(max_width, width)
                max_height = max(max_height, height)

    return max_width, max_height


def get_wallpaper_url(screen_res: Resolution) -> str:
    # id of the *Unsplash Editorial* collection
    coll_id = 317099

    url = f"https://source.unsplash.com/collection/{coll_id}/{screen_res[0]}x{screen_res[1]}"
    return url


def get_wallpaper_file() -> Path:
    pictures_dir = subprocess.run(
        ["xdg-user-dir", "PICTURES"], check=True, text=True, capture_output=True
    ).stdout.strip()
    file_name = ".unsplash_wallpaper.jpg"
    wallpaper_file = (Path(pictures_dir) / file_name).absolute()
    return wallpaper_file


def download(url: str, file: Path):
    chunk_size = 1024**2  # 1 MiB
    logging.info("downloading...")
    resp = requests.get(url, stream=True)
    with open(file, "wb") as fd:
        for chunk in resp.iter_content(chunk_size=chunk_size):
            fd.write(chunk)
    logging.info("download complete")


def apply_wallpaper(file: Path) -> None:
    schema = "org.gnome.desktop.background"
    keys = ["picture-uri", "picture-uri-dark"]

    value = f"file://{file}"
    for key in keys:
        subprocess.run(["gsettings", "set", schema, key, value], check=True)
    logging.info("applied wallpaper setting")


def main() -> None:
    parser = argparse.ArgumentParser()
    parser.add_argument("--debug", action="store_true", help="print debug information")
    args = parser.parse_args()

    logging.basicConfig(level=logging.DEBUG if args.debug else logging.INFO)

    max_screen_res = get_max_screen_res()
    logging.debug("max screen res = %s", max_screen_res)

    wallpaper_url = get_wallpaper_url(max_screen_res)
    logging.debug("wallpaper url = %s", wallpaper_url)

    wallpaper_file = get_wallpaper_file()
    logging.debug("wallpaper file = %s", wallpaper_file)

    download(wallpaper_url, wallpaper_file)
    apply_wallpaper(wallpaper_file)


if __name__ == "__main__":
    main()