daywall

A bash script to programatically select an appropriate wallpaper for what time of day it is. A second bash script to programatically alter the brightness of a wallpaper for what time of day it is.

Example of images

An image of thumbnails of images arranged by their calculated brightness.

Contents

  1. About
  2. License
  3. Prerequisites
  4. Installation
  5. Setup
  6. Usage
  7. Tweaking
  8. TODO

1. About

I have a lot of wallpapers, and I like to have them rotate. However, I also work varying hours, and don’t like to suddenly have a bright white background when it’s the middle of the night.

daywall uses online geolocation to find your latitude and longitude, determine how far away from mid-day the current hour is, and then chooses a random image from the directory (or directories) you specify with a (calculated) brightness appropriate to the time of day.

daywall2 uses online geolocation to find your latitude and longitude, determine how far away from mid-day the current hour is, and then chooses a random image from the directory (or directories) you specify and adjusts the brightness and contrast to fit within limits appropriate to the time of day.

2. License

This project is licensed under the MIT License. For the full license, see LICENSE.

3. Prerequisites

Important note: Now tuned for imagemagick 7.

	#imagemagick 7
	brightcolor=$(timeout 5 magick identify -format "%[fx:quantumrange*mean]" -colorspace Gray "${darker_filename}")
	#imagemagick 6
	#brightcolor=$(timeout 5 convert "${darker_filename}" -colorspace Gray -format "%[fx:quantumrange*image.mean]" info:)

and swap which one is commented out.

4. Installation

On Debian-like (including Ubuntu):

sudo apt install coreutils hdate bc fd-find curl gawk imagemagick

5. Setup

Daywall 2

If you wish to set your coordinates as an environment variable and not use the online lookup, do so like this:

export COORDS="22.73, -81.08

That’s latitude first, then longitude. The comma and space between them is required.

You do not need an INI or other configuration file.

Daywall

In $HOME/.config/daywall.ini place the topmost directory that contains your (default) wallpaper images, like so:

DIR=/PATH/TO/IMAGES

While not strictly required, daywall will squawk if you forget to specify a directory to scan on the command line if this is not set.

If you wish to set your coordinates as an environment variable and not use the online lookup, do so like this:

export COORDS="22.73, -81.08

That’s latitude first, then longitude. The comma and space between them is required.

Using with cron (both versions)

If you’re using daywall with cron, you’ll need to ensure that your environment variables (including DISPLAY=0.0) are properly passed, and that the XDG directories are appropriately assigned.

The easiest way to do this is through having your crontab entry be:

DISPLAY=0.0 /path/to/daywall_cronjob.sh

and editing daywall_cronjob.sh to pull in your appropriate .bashrc and deal with calling feh (or whatever you use to set the wallpaper).

One other thing to check is what your XDG directories are. I ran into this problem, because I’d changed XDG_CACHE_HOME (for random reasons) so it kept throwing errors.

To check for this, in a normal terminal window:

echo ${XDG_CONFIG_HOME}
echo ${XDG_CACHE_HOME}

If those directories aren’t $HOME/.config and $HOME/.local/state, then move those files as needed.

6. Usage

Daywall 2

daywall2.sh [OPTIONS]

If a directory is not provided, defaults to ${PWD}.

Options:

--loud    Provide extra output.
--high    Maximum high value for brightness
--low     Minimum low value for brightness
--dirs    directories to recursively search for files
--cords   Your coordinates to avoid lookup
--nobr    Do not brighten any image, just darken
--nodrk   Do not darken any image, just brighten

For example,

daywall2.sh --dirs /path/to/images /another/path/to/images --high 27000

The adjusted image will be placed at $XDG_CACHE_HOME/daywall_darkened.jpg

Tweaking

Try specifying --high and --low to keep it from maxing out on either end.  
The results can still sometimes look really silly if it chooses a very dark 
image around high noon.

Daywall

daywall.sh [directory] [options]

directory is optional if configuration file has the directory specified.

OPTIONS (must come after directory, if specified): –help: This text –darken: Darken the output image even further for my fellow nightwalkers –loud: extra output when running

If --loud is not invoked, the output will be a single full filename to use with the wallpaper setting program of your choice. For example:

feh --bg-fill --no-xinerama $(daywall.sh)

Need it darker?

Use the --darken option to have it convert and darken the image. Ensure that you have the $TMP environment variable set.

Adding files

The first time you run it (or add more files to what daywall knows about, it will be slow since it does the brightness analyzation and stores that data in a simple CSV file in $HOME/.config/daywall.cache. Images added to the directory specified in the INI file will be added on the next run automatically.

If you specify a directory on the commandline, that directory’s files will be analyzed and added to the simple list of images to be chosen from. So for example, if your “main” directory of wallpapers is $HOME/wallpapers and you wish to add images from “$HOME/morewalls” to daywall, then you will run once:

daywall.sh $HOME/morewalls

and the image files currently in that directory will be added. These additional directories will not be re-scanned for new images unless the directory is specified at run-time.

Image Selection

If an image is not found within the appropriate brightness range, daywall will increase the allowable brightness range (in both directions) automatically.

Additionally, daywall records the image it selects, and will not use the same file on the next run.

Tweaking

If there is any error with analyzing the brightness, it will be recorded in an error log in $XDG_CACHE_HOME/daywall.error, which is actually a simple CSV file. You should probably check for its existence when you’re actively adding files, as daywall will keep attempting to process them and it can get slow.

The values in the cache file can be manually adjusted if needed.

If you want to change the brightness values and their time of day (with more finesse than just adding the --darken switch), look for this section of the code:

    # THESE ARE THE BRIGHTNESS VALUES TO EDIT
    # 0 is MID-DAY
    case "${abs_time_diff}" in
        0)  highval=65000    
            lowval=54000
            ;;

highval in each set is the highest allowed brightness value, lowval is the lowest. The hour number is how far away the time is from the midpoint between sunrise and sunset (literally “mid-day”). So, for example, if you wanted a wider range of brightness values during the mid-day hour, you could change lowval to a lower number, like so:

        0)  highval=65000    
            lowval=45000
            ;;

8. TODO

This site is open source. Improve this page.