Improve large notification groups performance

src/animatedList/animatedList.vala

@@ -15,6 +15,37 @@ private struct WidgetHeights {
 private struct WidgetAlloc {
     float y;
     int height;
+
+    public WidgetAlloc () {
+        y = 0;
+        height = 0;
+    }
+}
+
+private class AnimationValueTarget : Object {
+    private double _progress = 0;
+    public double progress {
+        get {
+            return _progress;
+        }
+        set {
+            _progress = value;
+            cb (_progress);
+        }
+    }
+
+    public delegate void callback (double value);
+
+    private unowned callback ?cb;
+
+    public AnimationValueTarget (float init_value, callback cb) {
+        this._progress = init_value;
+        this.cb = cb;
+    }
+
+    public Adw.PropertyAnimationTarget get_animation_target () {
+        return new Adw.PropertyAnimationTarget (this, "progress");
+    }
 }
 
 public class AnimatedList : Gtk.Widget, Gtk.Scrollable {

src/controlCenter/widgets/notifications/notifications.vala

@@ -182,7 +182,7 @@ namespace SwayNotificationCenter.Widgets {
                 noti_groups_name.lookup_extended (param.name_id, null, out group);
             }
             if (group == null || ConfigModel.instance.notification_grouping == false) {
-                group = new NotificationGroup (param.name_id, param.display_name);
+                group = new NotificationGroup (param.name_id, param.display_name, viewport);
                 // Collapse other groups on expand
                 group.on_expand_change.connect ((expanded) => {
                     if (!expanded) {

src/meson.build

@@ -68,6 +68,7 @@ app_sources = [
   'dismissableWidget/dismissableWidget.vala',
   'notification/notification.vala',
   'notificationGroup/notificationGroup.vala',
+  'notificationGroup/expandableGroup.vala',
   'controlCenter/controlCenter.vala',
   widget_sources,
   'blankWindow/blankWindow.vala',