Add screen argument to IPC wallpaper random

* Add argument to specify on which screen to apply a random wallpaper
* if `all` is provided, the old behavior is kept: a random wallpaper is
applied to all screen.

Modules/Bar/Widgets/WallpaperSelector.qml

@@ -42,7 +42,7 @@ NIconButton {
                    PanelService.closeContextMenu(screen);
 
                    if (action === "random-wallpaper") {
-                     WallpaperService.setRandomWallpaper();
+                     WallpaperService.setRandomWallpaper(null);
                    }
                  }
   }

Modules/Panels/ControlCenter/Widgets/WallpaperSelector.qml

@@ -11,5 +11,5 @@ NIconButtonHot {
   icon: "wallpaper-selector"
   tooltipText: I18n.tr("wallpaper.panel.title")
   onClicked: PanelService.getPanel("wallpaperPanel", screen)?.toggle()
-  onRightClicked: WallpaperService.setRandomWallpaper()
+  onRightClicked: WallpaperService.setRandomWallpaper(null)
 }

Services/Control/IPCService.qml

@@ -405,9 +405,12 @@ Item {
       }
     }
 
-    function random() {
+    function random(screen: string) {
       if (Settings.data.wallpaper.enabled) {
-        WallpaperService.setRandomWallpaper();
+        if (screen === "all" || screen.trim().length === 0) {
+          screen = undefined;
+        }
+        WallpaperService.setRandomWallpaper(screen);
       }
     }
 

Services/UI/WallpaperService.qml

@@ -376,19 +376,29 @@ Singleton {
   }
 
   // -------------------------------------------------------------------
-  function setRandomWallpaper() {
+  function setRandomWallpaper(screen) {
     Logger.d("Wallpaper", "setRandomWallpaper");
 
     if (Settings.data.wallpaper.enableMultiMonitorDirectories) {
-      // Pick a random wallpaper per screen
-      for (var i = 0; i < Quickshell.screens.length; i++) {
-        var screenName = Quickshell.screens[i].name;
-        var wallpaperList = getWallpapersList(screenName);
+      if (screen === undefined) {
+        // Pick a random wallpaper per screen
+        for (var i = 0; i < Quickshell.screens.length; i++) {
+            var screenName = Quickshell.screens[i].name;
+            var wallpaperList = getWallpapersList(screenName);
 
+            if (wallpaperList.length > 0) {
+                var randomIndex = Math.floor(Math.random() * wallpaperList.length);
+                var randomPath = wallpaperList[randomIndex];
+                changeWallpaper(randomPath, screenName);
+            }
+        }
+      } else {
+        // Pick a random wallpaper for the screen argument
+        var wallpaperList = getWallpapersList(screen);
         if (wallpaperList.length > 0) {
           var randomIndex = Math.floor(Math.random() * wallpaperList.length);
           var randomPath = wallpaperList[randomIndex];
-          changeWallpaper(randomPath, screenName);
+          changeWallpaper(randomPath, screen);
         }
       }
     } else {
@@ -398,7 +408,7 @@ Singleton {
       if (wallpaperList.length > 0) {
         var randomIndex = Math.floor(Math.random() * wallpaperList.length);
         var randomPath = wallpaperList[randomIndex];
-        changeWallpaper(randomPath, undefined);
+        changeWallpaper(randomPath, screen);
       }
     }
   }
@@ -470,7 +480,7 @@ Singleton {
     if (mode === "alphabetical") {
       setAlphabeticalWallpaper();
     } else {
-      setRandomWallpaper();
+      setRandomWallpaper(null);
     }
   }