When i want to change the background in Archlinux, there's no option to add more wallpaper or picture into Deepin Desktop Environment. But i found apps that can help to change background in Deepin Desktop environment. It is Wally, wally is a desktop background / wallpaper changer for QT4.
The source code is here:
In archlinux, it's available on AUR:
$wget -c https://aur.archlinux.org/cgit/aur.git/snapshot/wally.tar.gz
$tar -xvzf wall.tar.gz
$sudo pacman -U *.pkg.tar.xz
There's no menu for wally, so run at command line:
Then it will appear on panel, right click on wally, then go to settings:
Then choose folder, and add your background/wallpaper folder, set the position then ok:
Right click again on Wally menu then choose play, and just next to choose the wallpaper, here's the results :
it will be also appear on Deepin wallpaper list:
Ok that's it.