celestial

Automatically change your desktop background based on the time of day.

Features

• Supports Windows, macOS and Linux (GNOME and Cinnamon desktop environments)
• Constant time or celestial-based triggers
• Simple background service/app

Installation

Linux

The easiest way to run celestial on Linux is with a systemd user service. To set it up perform the following steps:

1. Copy the celestial binary to a location in your home directory, I would recommend ~/.local/bin.
2. Modify the ExecStart value of celestial.service to point to the location of celestial. Note that this must be an absolute path, it cannot be relative or use variables such as $HOME.
3. Copy celestial.service to ~/.local/share/systemd/user/.
4. Run systemctl --user enable celestial and systemctl --user start celestial to enable and start celestial. Once enabled it will automatically start upon login.

Windows

Unfortunately user services aren't a thing on Windows, so the easiest way to run celestial on Windows is to set up a scheduled task to start celestial.exe on login.

macOS

To install simply install Celestial.app and add it to your login items.

You can also run the celestial binary yourself if you prefer (you will need to have desktoppr installed).

Configuration

The celestial config file is created at one of the following locations (depending on your OS):

• Linux: ~/.config/celestial/config.json
• Windows: %APPDATA%\Roaming\celestial\config.json
• maxOS: ~/Library/Application Support/celestial/config.json

celestial will create a config file on first start if it does not already exist. All configuration is performed through this file. celestial will automatically reload the settings if a change is made to the file.

{
  "triggers": [],     // array of wallpaper triggers
  "latitude": null,   // location latitude for celestial-based triggers
  "longitude": null   // location longitude for celestial-based triggers
}

Triggers

celestial has two types of trigger: time and celestial. To add a trigger, simply add it to the array in the config file. The order of triggers does not matter. You can make any combination of time or celestial triggers.

All trigger types have two properties in common:

• type - this defines the type of trigger, Time or Celestial
• path - this is the path of the wallpaper to display for a trigger. This should be an absolute path.

Time Triggers

Time triggers are the simplest trigger. They fire at a specific local time each day.

They are defined with a type value of Time, and have just one property: time. This is a time string of the format HH:mm:ss (24 hour format). This is the time that the trigger will fire at each day, so a trigger with a time value of 11:00:00 will fire at 11am local time each day.

Example

{
    "type": "Time",
    "time": "11:00:00",
    "path": "/path/to/some/image.png"
}

Celestial Triggers

Celestial triggers are triggers that fire depending on the position of celestial objects, e.g. the sun.

They are defined with a type value of Celestial, and have two properties:

• time - a celestial time (see below)
• offset - an optional constant offset from the celestial time

The possible values for Time are:

• "Dawn" - the start of dawn/civil twilight
• "Sunrise" - the start of sunrise (i.e. when the sun is first visible on the horizon)
• "SunUp" - when the sun is fully up (i.e. the bottom of the sun is on the horizon)
• "Noon" - when the sun is at it's highest point in the sky
• "SunSetting" - when the sun is about to start setting (i.e. when the bottom of the sun touches the horizon)
• "Sunset" - when the sun has set (i.e. disappeared below the horizon)
• "Dusk" - the end of dusk/civil twilight

Offset can be used to offset a constant amount from these celestial times. It has the same format as the time property of a time trigger, except it can also be negative.

Examples

Triggers at dawn:

{
    "type": "Celestial",
    "time": "Dawn",
    "path": "/path/to/some/image.png"
}

Triggers 1 hour before noon

{
    "type": "Celestial",
    "time": "Noon",
    "offset": "-01:00:00",
    "path": "/path/to/some/image.png"
}

Triggers 30 minutes after dusk

{
    "type": "Celestial",
    "time": "Dusk",
    "offset": "00:30:00",
    "path": "/path/to/some/image.png"
}

Example Configuration

{
  "triggers": [
    {
        "type": "Celestial",
        "time": "Dawn",
        "path": "/home/james/Pictures/Wallpapers/1.png"
    },
    {
        "type": "Celestial",
        "time": "SunUp",
        "path": "/home/james/Pictures/Wallpapers/2.png"
    },
    {
        "type": "Celestial",
        "time": "Noon",
        "offset": "-01:30:00",
        "path": "/home/james/Pictures/Wallpapers/3.png"
    },
    {
        "type": "Celestial",
        "time": "Noon",
        "path": "/home/james/Pictures/Wallpapers/4.png"
    },
    {
        "type": "Celestial",
        "time": "Noon",
        "offset": "01:30:00",
        "path": "/home/james/Pictures/Wallpapers/5.png"
    },
    {
        "type": "Celestial",
        "time": "Sunset",
        "offset": "-01:00:00",
        "path": "/home/james/Pictures/Wallpapers/6.png"
    },
    {
        "type": "Celestial",
        "time": "Sunset",
        "path": "/home/james/Pictures/Wallpapers/7.png"
    },
    {
        "type": "Celestial",
        "time": "Dusk",
        "path": "/home/james/Pictures/Wallpapers/8.png"
    },
    {
        "type": "Time",
        "time": "22:00:00",
        "path": "/home/james/Pictures/Wallpapers/9.png"
    }
  ],
  "latitude": 12.34,
  "longitude": -1.23
}

Downloads

Downloads can be found in releases here.

Build file sizes are quite large due to bundled .NET runtimes and incompatibilities with trimming.