gnome-wallpaper-slideshow is a Ruby gem that allows you to create and interact with the XML files that define wallpaper slideshows in GNOME. It supports both creating slideshows from scratch and loading existing slideshows.
slideshow = GnomeWallpaperSlideshow.new do
create_new_slideshow "slideshow.xml"
start_time Time.local 2013, 1, 13, 0, 0, 0 # Start the slideshow at midnight
add_wallpaper "test.jpg", 3600, 5 # Display this image for 1 hour with a 5 sec transition
add_wallpaper "other.jpg" 1800, 5 # Display this image for 30 minutes with a 5 sec transition
end
slideshow.save_xml
gem install gnome-wallpaper-slideshow
gnome-wallpaper-slideshow is distributed with a sample application called create-slideshow. This script takes the name of a directory containing image files, the amount of time to display each image, the transition time, and an output filename and produces a slideshow XML file.
gnome-wallpaper-slideshow is MIT licensed. See LICENSE.txt for details.