Automatic Theme Switcher

A program to switch between light and dark themes based on current night light status. This program has been written and designed predominantly for GNOME Desktop Environment but could be extended to other DE.

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Getting started

Installation using pre-built packages

To install and run this program, you need to have at least Python 3 (version 3.5 or later) and Pip installed on your system. Then you can simply download the file in dist folder with .whl extension, navigate to the dowload directory and run the below command.

pip3 install theme_switcher-0.1-py3-none-any.whl

Installation by building manually

If you want to build and install the package manually, you need to have setuptools and wheel packages installed on your computer. You can check if you have these packages by running following command.

$ pip3 list | grep -iE "wheel|setuptools"

In case you don't have these packages installed, run following commands in order to install them.

$ python3 -m pip3 install --user setuptools wheel

After the installation of these packages, clone this repository in any directory of your choice by using following command.

$ git clone https://github.com/nnishant776/theme-switcher.git

Then navigate to the newly created directory theme-switcher

$ cd theme-switcher/

Then run:

$ python3 setup.py bdist_wheel

Above command will create a file with .whl extension in dist folder. Then run the following command.

$ pip3 install dist/*.whl

This will install the program as a non-privileged user. The program will run automatically at startup after user login once configured. See the next section for configuration.

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Configuration

After the installation, a bash script file named theme_manager will be present in $HOME/.local/bin directory. The help output for this script is shown below.

$ theme_manager --help

Usage: 

theme_manager --help  Display this help print

theme_manager --initial-setup  Do initial setup before activating theme switcher

theme_manager --set-theme THEME  Set the one of the themes listed in the themes.json

theme_manager --uninstall  Uninstall the theme switcher

theme_manager --edit-themes  Edit/Add to the list of themes and its variants known to the program

To configure, first run

theme_manager --initial-setup

This will configure the program for autostart and install a systemd service file as mentioned above.

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Usage

By default, the program is configured to use the Adwaita's light and dark theme variants. To use your own theme, you can define the light and dark sets of the said theme in $HOME/.local/share/theme-switcher/themes.json file, either manually or by using theme_manager --edit-themes. This command will open themes.json file in your preferred editor, if one is set in environment, otherwise it will open the file using vi.

If your theme is already defined in themes.json, then you can directly set the theme using theme_manager --set-theme THEME_NAME. Make sure both light and dark variants of the theme are defined, otherwise it won't work. When the theme is set, it will automatically switch between the light and dark variants according to night light status (if enabled).

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Defining themes

Below is a sample definition of a theme

{
    "Adwaita": [
        {
            "gtk-theme": "Adwaita",
            "icon-theme": "Adwaita",
            "cursor-theme": "Adwaita",
            "name": ""
        },
        {
            "gtk-theme": "Adwaita-dark",
            "icon-theme": "Adwaita",
            "cursor-theme": "Adwaita",
            "name": ""
        }
    ]
}

Below is an explanation of the fields:

• gtk-theme : The name of GTK application theme which decoreates the windows and controls
• icon-theme : The name of icon theme, e.g., Breeze, Adwaita, Yaru, etc..
• cursor-theme : The name of cursor theme, if you are using something other than the default.
• name : The name of the GNOME Shell theme that you wish to use.

The first set of the above entries in the theme specification is are the values used for the 'light' variant of the theme and the next for the 'dark' variant.