Script day: check the currently set Plasma desktop wallpaper
I like to have some kind of slideshow as a desktop background wallpaper, and there are various ways of doing that – using your local picture library or multiple variations of remote image sources (everyone love NASA’s Astronomy Picture of the Day), and you can find a lot of discussions online about how best to go about automating setting the desktop’s background wallpaper image – in KDE Plasma it is particularly not that easy as you have to contend with multiple “activities”, with each has multiple screens, with each has multiple “desktop containments” – fortunately Plasma no longer supports different wallpapers for different virtual desktops – otherwise it would really have been a massive mess.
But sometimes I don’t want to change the wallpaper – just to figure out which one I’m looking it (maybe I want to delete it?). There isn’t any discussion about that on the internet, so I wrote this script and here it is for posterity (and also in this Github Gist):
#!/bin/bash
##
# Helper to find the user configured name of an activity, by its ID
function getActivityName() {
qdbus org.kde.ActivityManager /ActivityManager/Activities \
org.kde.ActivityManager.Activities.ActivityName "$1"
}
##
# Helper to list all the currently configured activities by their ID
function listActivityIds() {
qdbus org.kde.ActivityManager /ActivityManager/Activities \
org.kde.ActivityManager.Activities.ListActivities
}
##
# Helper to get the ID of the current activity
function currentActivity() {
qdbus org.kde.ActivityManager /ActivityManager/Activities \
org.kde.ActivityManager.Activities.CurrentActivity
}
activity="$1" ## allow the user to choose the activity to look at
screen="${2:-0}" ## allow the user to choose the screen to look at
# but default to the first screen, if they didn't specify
grep -qi plasma <<<"$DESKTOP_SESSION" || { echo "Not running under a Plasma desktop!">&2; exit 1; }
# if the user did not specify an activity, use the current one
[ -z "$activity" ] && activity=$(currentActivity)
# if the user specified the activity by name, locate the ID
if [ -z "$(getActivityName "$activity")" ]; then
activities=( $(listActivityIds) )
aname="$activity"
activity=
for aid in "${activities[@]}"; do
if [ "$aname" == "$(getActivityName $aid)" ]; then
activity=$aid
fi
done
fi
[ -z "$activity" ] && { echo "Activity '$activity' was not found!">&2; exit 1; }
# The meat of the thing - ask Plasma to run our script
qdbus org.kde.plasmashell /PlasmaShell org.kde.PlasmaShell.evaluateScript "
var actId = '$activity';
var scr = $screen;
var ds = desktops(); // load the containments
for (let d of ds) { // and walk through them
// skip any containment that does not match activity and screen
if (d.readConfig('activityId') != actId ||
d.readConfig('lastScreen') != scr)
continue;
// prepare to read the General configuration (where plugins normally
// put the current image)
d.currentConfigGroup = Array('Wallpaper',d.wallpaperPlugin,'General');
// identify the wallpaper plugin so we can read it properly
if (d.wallpaperPlugin == 'org.kde.slideshow') {
print(d.readConfig('Image').replace('file://',''));
} else if (d.wallpaperPlugin == 'org.kde.image') {
print(d.readConfig('Image').replace('file://',''));
} else if (d.wallpaperPlugin == 'org.kde.potd') {
print('Picture of the Day (Provider: ' + d.readConfig('Provider') +
') does not support reading the current image');
} else {
print('Unsupported wallpaper plugin: '+d.wallpaperPlugin+'\n');
}
break;
}"To run this script, create a new text file – I recommend as ~/.local/bin/read-plasma-wallpaper – and paste the script, then give that script execution permissions. When you run it, it will output the full path to the current desktop background wallpaper image to the terminal.