How to change your wallpaper dynamically

0. Prerequisites

For image downloads, we use python packages requests. And we use json to process your data from requests.get.

For local wallpaper change, we use applescript grammar, which is ugly and documentation missing.

For script manipulation, we use bash grammar.

1. Project Tree

~/Pictures/Wallpapers
├── Display
│   ├── your_downloaded_pictures1.jpg
│   └── your_downloaded_pictures2.jpg
├── README.md
├── change_wallpaper.scpt
├── download_wallpaper.py
└── run.sh

2. Deployment Flow

2.1 Download Pics From Bing

Bing provides API for picture link's uri at https://www.bing.com/HPImageArchive.aspx?format=js&idx={}&n={}. So we can just get the picture storage link from this and directly download pictures from https://s.cn.bing.net/" + uri.

2.2 Employ applescript to manipulate wallpaper-related API

Talk is cheap, show you the code.

The truth is: I'm not familiar with applescript either...

on run argv
	set wallpaperName to item 1 of argv
	set wallpaperPath to POSIX path of "~/Pictures/Wallpapers/Display/" & (wallpaperName as string) 
	log wallpaperPath
  tell application "System Events"
      set theDesktops to a reference to every desktop
      repeat with x from 1 to (count theDesktops)
          set picture of item x of the theDesktops to wallpaperPath
      end repeat
  end tell
end run

2.3 Write a script to pipeline the download and change

To get the latest picture, we should sort files at picture hall, and that is ls -lt where parameter -t means sort the results by descending time order.

To get the file name from ls result, we use awk. awk {print $i} prints the ith element from the raw text, sepped by spacing by default.

ls -lt ./Display| head -n 2 | tail -n 1 | awk '{print $9}'

2.4 Use Crontab to set Timed Task

Firstly, we use this command

crontab -e

Argument -e means automatically create a file (for example, my crontab script is saved at /tmp/crontab.GLqTBkM4Fb), and open the editor to write instruction.

And we type this in vim.

0 * * * * /path/to/your/run.sh

num1(*) num2(*) num3(*) num4(*) num5(*) is divided into five fields, each representing minutes, hours, day of month, month, and day of week.

• num1 (minutes): Indicates the start of each hour.
• num2 (hours): Means every hour.
• num3 (day of month): Indicates every day of the month.
• num4 (month): Means every month.
• num5 (day of week): Represents every day of the week.

Symbol * means that the script is executed every minute (hours, ...)