Add event-driven wallpaper rotation

config/dot/quickshell/services/Wallpaper.qml

@@ -20,6 +20,13 @@ Singleton {
     property bool scanning: false
     property var transaction: null
     property bool startupRestoreEnabled: true
+    property var outputOverride: null
+    property var candidateOverride: null
+    property string slideshowPath: ""
+    property int slideshowIndex: -1
+    property var shuffleBag: []
+    property int slideshowIntervalOverrideMs: 0
+    property bool pendingHotplugReapply: false
 
     readonly property string configured: DesktopPreferences.get("wallpaperPath")
     readonly property string shippedPath: `${Quickshell.env("HOME")}/Pictures/Wallpapers/faroe_islands.jpg`
@@ -32,8 +39,14 @@ Singleton {
     }
     readonly property bool busy: root.transaction !== null
         || applyProcess.running || verifyProcess.running
+    readonly property var slideshowCollection: WallpaperPolicy.validCollection(
+        DesktopPreferences.get("wallpaperSlideshowPaths") ?? [], root.candidates([]))
+    readonly property bool slideshowTimerRunning: slideshowTimer.running
+    readonly property string outputSignature: root.outputNames().slice().sort().join("|")
 
     property var outputNames: function() {
+        if (Array.isArray(root.outputOverride))
+            return root.outputOverride.slice();
         return Quickshell.screens.map(screen => screen.name).filter(name => !!name);
     }
 
@@ -79,6 +92,7 @@ Singleton {
             if (exitCode !== 0) {
                 root.lastError = "Hyprpaper did not apply that background.";
                 root.transaction = null;
+                root.schedulePendingHotplug();
                 return;
             }
             root.drainTransaction();
@@ -110,6 +124,34 @@ Singleton {
         }
     }
 
+    Timer {
+        id: slideshowTimer
+        interval: root.slideshowIntervalOverrideMs > 0
+            ? root.slideshowIntervalOverrideMs
+            : DesktopPreferences.get("wallpaperIntervalMinutes") * 60000
+        repeat: true
+        running: DesktopPreferences.get("wallpaperMode") === "slideshow"
+            && root.slideshowCollection.length >= 2 && !root.busy
+        onTriggered: root.advanceSlideshow()
+    }
+
+    Timer {
+        id: outputSettle
+        interval: 350
+        onTriggered: {
+            if (root.busy) {
+                root.pendingHotplugReapply = true;
+                return;
+            }
+            root.applyCurrentPolicy(false);
+        }
+    }
+
+    onOutputSignatureChanged: {
+        if (Object.keys(root.activeByOutput).length > 0)
+            outputSettle.restart();
+    }
+
     function rescan(): void {
         if (scan.running)
             return;
@@ -124,7 +166,9 @@ Singleton {
 
     function candidates(extra: var): var {
         const result = [];
-        for (const path of root.available.concat([root.shippedPath, root.configured]).concat(extra || [])) {
+        const discovered = Array.isArray(root.candidateOverride)
+            ? root.candidateOverride : root.available;
+        for (const path of discovered.concat([root.shippedPath, root.configured]).concat(extra || [])) {
             if (typeof path === "string" && /^\/[^,\n]+$/.test(path) && !result.includes(path))
                 result.push(path);
         }
@@ -139,7 +183,7 @@ Singleton {
             intervalMinutes: DesktopPreferences.get("wallpaperIntervalMinutes") ?? 30,
             shuffle: DesktopPreferences.get("wallpaperShuffle") !== false,
             assignments: DesktopPreferences.get("wallpaperPerMonitor") ?? ({}),
-            slideshowPath: root.active
+            slideshowPath: root.slideshowPath !== "" ? root.slideshowPath : root.active
         };
     }
 
@@ -165,6 +209,10 @@ Singleton {
             assignments: WallpaperPolicy.validAssignments(policy.assignments || {}, candidatePaths),
             slideshowPath: WallpaperPolicy.validPath(policy.slideshowPath, candidatePaths)
                 ? policy.slideshowPath : rawGlobal,
+            nextShuffleBag: Array.isArray(policy.nextShuffleBag)
+                ? policy.nextShuffleBag.slice() : root.shuffleBag.slice(),
+            nextSlideshowIndex: Number.isInteger(policy.nextSlideshowIndex)
+                ? policy.nextSlideshowIndex : root.slideshowIndex,
             candidates: candidatePaths
         };
     }
@@ -240,6 +288,7 @@ Singleton {
         if (!matches) {
             root.lastError = "Hyprpaper did not confirm that background.";
             root.transaction = null;
+            root.schedulePendingHotplug();
             return;
         }
 
@@ -247,8 +296,14 @@ Singleton {
         root.activeByOutput = observed;
         root.transaction = null;
         root.lastError = "";
+        if (completed.automatic) {
+            root.slideshowPath = completed.policy.slideshowPath;
+            root.shuffleBag = completed.policy.nextShuffleBag;
+            root.slideshowIndex = completed.policy.nextSlideshowIndex;
+        }
         if (completed.persist)
             root.persistPolicy(completed.policy);
+        root.schedulePendingHotplug();
     }
 
     function persistPolicy(policy: var): void {
@@ -264,6 +319,41 @@ Singleton {
         return root.applyPolicy(root.currentPolicy(), persist === true, false);
     }
 
+    function schedulePendingHotplug(): void {
+        if (!root.pendingHotplugReapply)
+            return;
+        root.pendingHotplugReapply = false;
+        outputSettle.restart();
+    }
+
+    function advanceSlideshow(): bool {
+        if (root.busy)
+            return false;
+        const collection = root.slideshowCollection;
+        if (collection.length < 2)
+            return false;
+
+        const current = root.slideshowPath !== ""
+            ? root.slideshowPath
+            : (root.active !== "" ? root.active : collection[0]);
+        const policy = root.currentPolicy();
+        policy.mode = "slideshow";
+        policy.collection = collection;
+
+        if (DesktopPreferences.get("wallpaperShuffle") !== false) {
+            const next = WallpaperPolicy.shuffledNext(
+                collection, root.shuffleBag, current, Math.random);
+            policy.slideshowPath = next.path;
+            policy.nextShuffleBag = next.bag;
+            policy.nextSlideshowIndex = collection.indexOf(next.path);
+        } else {
+            policy.slideshowPath = WallpaperPolicy.orderedNext(collection, current);
+            policy.nextShuffleBag = [];
+            policy.nextSlideshowIndex = collection.indexOf(policy.slideshowPath);
+        }
+        return root.applyPolicy(policy, false, true);
+    }
+
     function setSingle(path: string): bool {
         const effectivePath = path === "" ? root.shippedPath : path;
         const allowed = root.candidates([]);