More than just a painting on the wall
As you might know, the very background of a Plasma workspace, a.k.a “wallpaper”, is painted by a special kind of full-screen applet, in Plasma terms “wallpaper plugin”. These wallpaper plugins not only allow to do static display of e.g. a given picture, but also some dynamically changing display, even interactively controlled by the user.
One can select the type of the wallpaper by selecting between available wallpaper plugins in the settings of the workspace. A default Plasma installation usually provides wallpaper plugins for at least the types “Color”, “Image”, and “Slideshow” (sources in plasma-workspace repository), and can also have “Picture of the Day” as well as the animated graphic wallpapers “Haneau” & “Hunyango” (sources in kdeplasma-addons repository).
Bring your own wallpaper
One of the Plasma concepts being customizability, one of course can write their own wallpaper plugin for a complete custom look and behaviour of the background.
So people have done. And not only for demoing the power of QtQuick2 and the OpenGL backends with some interactive fireworks wallpaper (sound effects there though left to user as by example of linked video 😉 ).
One can find e.g. wallpaper plugins like “Video wallpaper” (original link dead now) or “Ken Burns effect slideshow” (original link dead now) in the “Plasma Wallpaper plugins” category in store.kde.org. Or soon use (again) the Marble-based “World Map wallpaper” (sadly got broken unnoticed and only restored in time for KDE Applications 18.04). Or in the future find relaxation with the animated Asciiquarium.
Then there is also the Plasma wallpaper plugin example with animated falling tree leaves (sources in plasma-framework repository).
Templates for some DIY in the hobby room/garage
To help you implementing your own idea for a wallpaper plugin, the Plasma libraries part of KDE Frameworks are providing you with a Plasma wallpaper plugin template in the kapptemplate format, as supported by KAppTemplate or KDevelop. It is usually part of the additional development package in Linux distributions (e.g. “plasma-framework-devel”). Starting with upcoming KDE Frameworks version 5.45 this month there will be even two versions, the existing template for a QML-only version and one new template for a version where one wants to include other compiled code using an own QML extension plugin (get this template already here).
With such templates, an initial running version of your own wallpaper plugin is just a few steps away. Create a new project from the template, e.g. with KAppTemplate…
… then follow the README in the created sources to build and install the wallpaper plugin. Both templates generate some sample code which shows some configurable text in the middle of the wall, eh, background. So open the settings dialog, select the new wallpaper plugin, enter some text in the sample configuration field and apply…
And then go and make the Plasma wall all yours 🙂