[gtk/wip/otte/for-main: 1/2] singleselection: Be more careful about notifies

[Benjamin Otte <otte src gnome org>]

commit 5e8b294faf38f9a5e3323c1c983877caee9d6421
Author: Benjamin Otte <otte redhat com>
Date:   Mon Oct 17 19:54:40 2022 +0200

    singleselection: Be more careful about notifies
    
    We don't want to notify::selected or notify::selected-item if they
    didn't change.
    This will bring performance benefits on frequently changing lists.
    
    In particular, if lists get filtered or reordered, but the selected item
    stays in the list, not doing a notify::selected-item will avoid updates
    in connected handlers like GtkDropdown (and its handlers), thereby
    avoiding lots of unnecessary updates.

 gtk/gtksingleselection.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)
---
diff --git a/gtk/gtksingleselection.c b/gtk/gtksingleselection.c
index fb5c1ad435..7e06575872 100644
--- a/gtk/gtksingleselection.c
+++ b/gtk/gtksingleselection.c
@@ -200,7 +200,6 @@ gtk_single_selection_items_changed_cb (GListModel         *model,
     {
       self->selected += added - removed;
       g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_SELECTED]);
-      g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_SELECTED_ITEM]);
     }
   else
     {
@@ -216,7 +215,6 @@ gtk_single_selection_items_changed_cb (GListModel         *model,
                 {
                   self->selected = position + i;
                   g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_SELECTED]);
-                  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_SELECTED_ITEM]);
                 }
 
               g_object_unref (item);
@@ -226,6 +224,8 @@ gtk_single_selection_items_changed_cb (GListModel         *model,
         }
       if (i == added)
         {
+          guint old_selected = self->selected;
+
           /* the item really was deleted */
           g_clear_object (&self->selected_item);
           if (self->autoselect)
@@ -266,7 +266,9 @@ gtk_single_selection_items_changed_cb (GListModel         *model,
               g_clear_object (&self->selected_item);
               self->selected = GTK_INVALID_LIST_POSITION;
             }
-          g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_SELECTED]);
+          if (old_selected != self->selected)
+            g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_SELECTED]);
+          /* the item was deleted above, so this is guaranteed to be new, even if the position didn't change 
*/
           g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_SELECTED_ITEM]);
         }
     }