[gtk/wip/otte/listview: 926/1040] listitemmanager: Switch from "insert_before" to "insert_after" argumnet

[Benjamin Otte <otte src gnome org>]

commit ccb15825d5ecf80c67d79739fd40f129331af524
Author: Benjamin Otte <otte redhat com>
Date:   Fri Sep 28 02:05:46 2018 +0200

    listitemmanager: Switch from "insert_before" to "insert_after" argumnet
    
    We reorder widgets start to end, so when reusing a list item, we
    correctly know the previous sibling for that list item, but not the
    next sibling yet. We just know the widget it should ultimately be in
    front of.
    So we can do a more correct guess of the list item's place in the widget
    tree if we think about where to place an item like this.
    
    Actually using this change will come in the next commit.

 gtk/gtklistitemmanager.c        | 20 ++++++++++----------
 gtk/gtklistitemmanagerprivate.h |  4 ++--
 gtk/gtklistview.c               | 26 ++++++++++++++------------
 3 files changed, 26 insertions(+), 24 deletions(-)
---
diff --git a/gtk/gtklistitemmanager.c b/gtk/gtklistitemmanager.c
index cce8eda34d..32687440b2 100644
--- a/gtk/gtklistitemmanager.c
+++ b/gtk/gtklistitemmanager.c
@@ -232,8 +232,8 @@ gtk_list_item_manager_change_contains (GtkListItemManagerChange *change,
  * gtk_list_item_manager_acquire_list_item:
  * @self: a #GtkListItemManager
  * @position: the row in the model to create a list item for
- * @next_sibling: the widget this widget should be inserted before or %NULL
- *     if none
+ * @prev_sibling: the widget this widget should be inserted before or %NULL
+ *     if it should be the first widget
  *
  * Creates a list item widget to use for @position. No widget may
  * yet exist that is used for @position.
@@ -249,20 +249,20 @@ gtk_list_item_manager_change_contains (GtkListItemManagerChange *change,
 GtkWidget *
 gtk_list_item_manager_acquire_list_item (GtkListItemManager *self,
                                          guint               position,
-                                         GtkWidget          *next_sibling)
+                                         GtkWidget          *prev_sibling)
 {
   GtkListItem *result;
   gpointer item;
 
   g_return_val_if_fail (GTK_IS_LIST_ITEM_MANAGER (self), NULL);
-  g_return_val_if_fail (next_sibling == NULL || GTK_IS_WIDGET (next_sibling), NULL);
+  g_return_val_if_fail (prev_sibling == NULL || GTK_IS_WIDGET (prev_sibling), NULL);
 
   result = gtk_list_item_factory_create (self->factory);
 
   item = g_list_model_get_item (self->model, position);
   gtk_list_item_factory_bind (self->factory, result, position, item);
   g_object_unref (item);
-  gtk_widget_insert_before (GTK_WIDGET (result), self->widget, next_sibling);
+  gtk_widget_insert_after (GTK_WIDGET (result), self->widget, prev_sibling);
 
   return GTK_WIDGET (result);
 }
@@ -271,8 +271,8 @@ gtk_list_item_manager_acquire_list_item (GtkListItemManager *self,
  * gtk_list_item_manager_try_acquire_list_item_from_change:
  * @self: a #GtkListItemManager
  * @position: the row in the model to create a list item for
- * @next_sibling: the widget this widget should be inserted before or %NULL
- *     if none
+ * @prev_sibling: the widget this widget should be inserted after or %NULL
+ *     if it should be the first widget
  *
  * Like gtk_list_item_manager_acquire_list_item(), but only tries to acquire list
  * items from those previously released as part of @change.
@@ -286,20 +286,20 @@ GtkWidget *
 gtk_list_item_manager_try_reacquire_list_item (GtkListItemManager       *self,
                                                GtkListItemManagerChange *change,
                                                guint                     position,
-                                               GtkWidget                *next_sibling)
+                                               GtkWidget                *prev_sibling)
 {
   GtkListItem *result;
   gpointer item;
 
   g_return_val_if_fail (GTK_IS_LIST_ITEM_MANAGER (self), NULL);
-  g_return_val_if_fail (next_sibling == NULL || GTK_IS_WIDGET (next_sibling), NULL);
+  g_return_val_if_fail (prev_sibling == NULL || GTK_IS_WIDGET (prev_sibling), NULL);
 
   /* XXX: can we avoid temporarily allocating items on failure? */
   item = g_list_model_get_item (self->model, position);
   if (g_hash_table_steal_extended (change->items, item, NULL, (gpointer *) &result))
     {
       gtk_list_item_factory_update (self->factory, result, position);
-      gtk_widget_insert_before (GTK_WIDGET (result), self->widget, next_sibling);
+      gtk_widget_insert_after (GTK_WIDGET (result), self->widget, prev_sibling);
       /* XXX: Should we let the listview do this? */
       gtk_widget_queue_resize (GTK_WIDGET (result));
     }
diff --git a/gtk/gtklistitemmanagerprivate.h b/gtk/gtklistitemmanagerprivate.h
index cf7721bc6c..0f1d1bddd1 100644
--- a/gtk/gtklistitemmanagerprivate.h
+++ b/gtk/gtklistitemmanagerprivate.h
@@ -60,12 +60,12 @@ gboolean                gtk_list_item_manager_change_contains   (GtkListItemMana
 
 GtkWidget *             gtk_list_item_manager_acquire_list_item (GtkListItemManager     *self,
                                                                  guint                   position,
-                                                                 GtkWidget              *next_sibling);
+                                                                 GtkWidget              *prev_sibling);
 GtkWidget *             gtk_list_item_manager_try_reacquire_list_item
                                                                 (GtkListItemManager     *self,
                                                                  GtkListItemManagerChange *change,
                                                                  guint                   position,
-                                                                 GtkWidget              *next_sibling);
+                                                                 GtkWidget              *prev_sibling);
 void                    gtk_list_item_manager_update_list_item  (GtkListItemManager     *self,
                                                                  GtkWidget              *item,
                                                                  guint                   position);
diff --git a/gtk/gtklistview.c b/gtk/gtklistview.c
index 7ef2529e3e..c9cfc7c840 100644
--- a/gtk/gtklistview.c
+++ b/gtk/gtklistview.c
@@ -404,7 +404,7 @@ gtk_list_view_ensure_rows (GtkListView              *self,
 {
   ListRow *row, *new_row;
   guint i, offset;
-  GtkWidget *insert_before;
+  GtkWidget *insert_after;
 
   gtk_list_view_release_rows (self);
 
@@ -417,7 +417,7 @@ gtk_list_view_ensure_rows (GtkListView              *self,
       gtk_rb_tree_node_mark_dirty (row);
     }
 
-  insert_before = gtk_widget_get_first_child (GTK_WIDGET (self));
+  insert_after = NULL;
 
   for (i = self->anchor_start; i < self->anchor_end; i++)
     {
@@ -440,21 +440,21 @@ gtk_list_view_ensure_rows (GtkListView              *self,
               new_row->widget = gtk_list_item_manager_try_reacquire_list_item (self->item_manager,
                                                                                change,
                                                                                i,
-                                                                               insert_before);
+                                                                               insert_after);
             }
           if (new_row->widget == NULL)
             {
               new_row->widget = gtk_list_item_manager_acquire_list_item (self->item_manager,
                                                                          i,
-                                                                         insert_before);
+                                                                         insert_after);
             }
         }
       else
         {
           if (update_start <= i)
             gtk_list_item_manager_update_list_item (self->item_manager, new_row->widget, i);
-          insert_before = gtk_widget_get_next_sibling (new_row->widget);
         }
+      insert_after = new_row->widget;
     }
 }
 
@@ -888,18 +888,18 @@ gtk_list_view_model_items_changed_cb (GListModel  *model,
       /* The anchor was removed, do a more expensive rebuild trying to find if
        * the anchor maybe got readded somewhere else */
       ListRow *row, *new_row;
-      GtkWidget *insert_before;
+      GtkWidget *insert_after;
       guint i, offset, anchor_pos;
       
       row = gtk_list_view_get_row (self, position, &offset);
-      for (new_row = row;
+      for (new_row = gtk_rb_tree_node_get_previous (row);
            new_row && new_row->widget == NULL;
-           new_row = gtk_rb_tree_node_get_next (new_row))
-        ;
+           new_row = gtk_rb_tree_node_get_previous (new_row))
+        { }
       if (new_row)
-        insert_before = new_row->widget;
+        insert_after = new_row->widget;
       else
-        insert_before = NULL; /* we're at the end */
+        insert_after = NULL; /* we're at the start */
 
       for (i = 0; i < added; i++)
         {
@@ -908,7 +908,7 @@ gtk_list_view_model_items_changed_cb (GListModel  *model,
           widget = gtk_list_item_manager_try_reacquire_list_item (self->item_manager,
                                                                   change,
                                                                   position + i,
-                                                                  insert_before);
+                                                                  insert_after);
           if (widget == NULL)
             {
               offset++;
@@ -938,6 +938,8 @@ gtk_list_view_model_items_changed_cb (GListModel  *model,
             }
 
           new_row->widget = widget;
+          insert_after = widget;
+
           if (widget == self->anchor)
             {
               anchor_pos = position + i;