prefs: keep the wallpaper transition

Reassigned only on a real change: every page's save rereads the file, and
a new object would reset the transitions page's unsaved draft.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 14 insertions, 1 deletions

diff --git a/desktop/Prefs.qml b/desktop/Prefs.qml
index 8634f87..c238990 100644
--- a/desktop/Prefs.qml
+++ b/desktop/Prefs.qml
@@ -63,6 +63,15 @@ Singleton {
         root.write(Object.assign({}, root.doc, { wallEngine: w }));
     }
 
+    // The wallpaper transition as saved, or null for the defaults
+    // (modules/appearance/TransitionPick.js, which also validates what is
+    // read here).
+    property var wallTransition: null
+    function setWallTransition(t) {
+        root.wallTransition = t;
+        root.write(Object.assign({}, root.doc, { wallTransition: t }));
+    }
+
     // The whole parsed object, so a write keeps keys this version does not
     // know about.
     property var doc: ({})
@@ -126,6 +135,10 @@ Singleton {
             folderH: str(we.folderH), folderV: str(we.folderV),
             homeH: str(we.homeH), homeV: str(we.homeV),
         };
+        // Only on a real change: any page's save rereads this file, and a new
+        // object here would throw away the transitions page's draft.
+        const wt = parsed.wallTransition !== undefined ? parsed.wallTransition : null;
+        if (JSON.stringify(wt) !== JSON.stringify(root.wallTransition)) root.wallTransition = wt;
     }
 
     FileView {
@@ -140,6 +153,6 @@ Singleton {
         onFileChanged: reload()
         onLoaded: root.reparse()
         // Missing file: the defaults, and nothing written.
-        onLoadFailed: { root.doc = {}; root.pinnedIp = ""; root.presets = null; root.settingsSidebar = 200; root.assistantModel = ""; root.wallEngine = root.wallEngineDefaults; }
+        onLoadFailed: { root.doc = {}; root.pinnedIp = ""; root.presets = null; root.settingsSidebar = 200; root.assistantModel = ""; root.wallEngine = root.wallEngineDefaults; root.wallTransition = null; }
     }
 }