backgroundchooser

#!/bin/bash
# backgroundchooser
# Chooses a random background file from a dir with backrgrounds.

# Copyright (C) 2014-2015 Alexander Swen <alex@swen.nu>

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

# Alexander Swen

# CHANGELOG:
# 2018-01-25 A.Swen Created.
# 2018-11-04 A.Swen Added:
#                   - Suggest feature to support other tools (see examples).
#                   - Link feature to support i3lock from within the i3 config.
#                   - Function to transform JPG's to PNG files (because
#                     https://github.com/i3/i3lock/issues/68).
#                   - Choice to remove the original JPG file after converion.

# This script requires the tools 'feh' and 'convert' (from Imagemagick)

## USAGE EXAMPLES:
# This script could be run from a users cron
# 15 * * * * /data/git/alex/scripts/backgroundchooser -d /data/backgrounds

# It could be launched each time i3 starts by adding this to the i3 config:
# exec --no-startup-id /data/git/alex/scripts/backgroundchooser --dir /data/backgrounds

# It can also be used to set a random background before i3lock is started:
# bindsym $win+l "exec --no-startup-id /data/git/alex/scripts/backgroundchooser --dir /data/backgrounds --link /tmp/background.png; exec --no-startup-id i3lock -tei /tmp/background.png -c 000000"

# I also use it just before my laptop goes to sleep. I changed /usr/share/acpi-support/screenblank
# which has a line with i3lock (I commented all other lock optiones)
# su "$XUSER" -s /bin/sh -c "/usr/bin/i3lock -tei $(/data/git/alex/scripts/backgroundchooser --dir /data/backgrounds --suggest) -c 000000"


# SETTINGS
date=$(date +%Y%m%d)
me=$(basename $0)
mydir=$(dirname $0)
# Case insensitive list of filetypes
filetypes='*.png'

# FUNCTIONS
die () {
  rc=$1
  shift
  printf '%s\n' "=====================" >&2
  printf '%s\n' "==== FATAL ERROR ====" >&2
  printf '%s\n\n' "=====================" >&2
  printf '%s\n\n' "$@" >&2
  exit $rc
}

usage () {
  printf '%s\n' "===============" >&2
  printf '%s\n' "==== USAGE ====" >&2
  printf '%s\n\n' "===============" >&2
  printf '%s\n' "Usage: ${me} [--dir|-d (directory with backgrounds)] [--suggest|-s] [--link|-l] [--remove_jpg|-r]" >&2
  printf '%s\n\n' "example: ${me} --dir /data/backgrounds --link" >&2
  exit 1
}

get_options () {
  while [[ $# -gt 0 ]]; do
    case "$1" in
      --dir|-d)
        shift
        export backgrounds_dir="$1"
        shift
        ;;
      --link|-l)
        shift
        export link=1
        export linktarget="$1"
        shift
        ;;
      --remove_jpg|-r)
        shift
        export remove_jpg=1
        ;;
      --suggest|-s)
        shift
        export suggest=1
        ;;
      -h|--help)
        usage
        ;;
      *)
        usage
        ;;
    esac
  done
}

convert_to_png () {
  [ -x /usr/bin/convert ] || die 20 "Convert not found."
  old_background="$background"
  background="$(echo $background|sed -e 's?\(^.*\.\)\(jp[e*]g\)$?\1png?')"
  [ "$background" = "$old_background" ] && die 14 "Old and new background are the same."
  [ -f "background" ] && die 15 "A file with the name $background already exists."
  /usr/bin/convert "$old_background" "$background" || die 25 "Converting the background to png format failed."
  [ $remove_jpg -eq 1 ] && rm "$old_background"
}

log () { printf '%s %s\n' "$(date +%F' '%T)" "$@"; }
log_warn () { printf '%s %s\n' "$(date +%F' '%T)" "$@" >&2; }

# SCRIPT

link=0
suggest=0
remove_jpg=0
if [[ $# -gt 0 ]];then
  get_options $@
fi

# Switch to backgrounds dir or die
[ -n "$backgrounds_dir" ] || backgrounds_dir=$(pwd)

# Build an array with background files
shopt -s nocaseglob
[ -d "$backgrounds_dir" ] && cd "$backgrounds_dir" || die "$backgrounds_dir not found."
background_files=($filetypes)

# The background selection
if [ ${#background_files[*]} -gt 1 ];then
  # Pick a random background
  background_file="${background_files[$(($RANDOM%${#background_files[*]}))]}"
  background="${backgrounds_dir}/${background_file}"
  if [[ "$background" =~ ^(.*\.(jpeg|jpg)$) ]] ;then
    convert_to_png "$background"
  fi
elif [ ${#background_files[*]} -eq 1 ];then
  background="$backgrounds_dir/${background_files[0]}"
  if [[ "$background" =~ ^(.*\.(jpeg|jpg)$) ]] ;then
    convert_to_png "$background"
  fi
else
  if [ $suggest -eq 1 ];then
    # If nothing to be found just throw the default
    log_warn "No backgrounds found, falling back to default mosquito."
    background=/home/alex/mug.png
  else
    die 1 "No suitable backgrounds found in $backgrounds_dir."
  fi
fi

# Use the background
if [ $suggest -eq 1 ];then
  echo $background
elif [ $link -eq 1 ];then
  if [ -z "$linktarget" ];then
    die 10 "\$linktarget not set"
  else
    log "Linking $background to $linktarget."
    ln -sf "$background" "$linktarget"
  fi
else
  # Set that background
  log "I have chosen $background"
  if [ "$XDG_CURRENT_DESKTOP" == "i3" ];then
    feh --bg-fill $background
  elif [ "$XDG_CURRENT_DESKTOP" == "GNOME" ];then
    gsettings set org.gnome.desktop.background picture-uri $background
    gsettings set org.gnome.desktop.background picture-uri-dark $background
  else
    gsettings set org.gnome.desktop.background picture-uri $background
    gsettings set org.gnome.desktop.background picture-uri-dark $background
    #die 12 "I don't yet know how to set a background on $XDG_CURRENT_DESKTOP"
  fi
fi

exit 0

# END